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Prevention and control of seasonal influenza with vaccines: Recommendations of the Advisory Committee On Immunization Practices — United States, 2023–24 influenza season
Grohskopf LA , Blanton LH , Ferdinands JM , Chung JR , Broder KR , Talbot HK . MMWR Recommendations and Reports 2023 72 (2) This report updates the 2022–23 recommendations of the Advisory Committee on Immunization Practices (ACIP) concerning the use of seasonal influenza vaccines in the United States (MMWR Recomm Rep 2022;71[No. RR-1]:1–28). Routine annual influenza vaccination is recommended for all persons aged ≥6 months who do not have contraindications. All seasonal influenza vaccines expected to be available in the United States for the 2023–24 season are quadrivalent, containing hemagglutinin (HA) derived from one influenza A(H1N1)pdm09 virus, one influenza A(H3N2) virus, one influenza B/Victoria lineage virus, and one influenza B/Yamagata lineage virus. Inactivated influenza vaccines (IIV4s), recombinant influenza vaccine (RIV4), and live attenuated influenza vaccine (LAIV4) are expected to be available. For most persons who need only 1 dose of influenza vaccine for the season, vaccination should ideally be offered during September or October. However, vaccination should continue after October and throughout the season as long as influenza viruses are circulating and unexpired vaccine is available. Influenza vaccines might be available as early as July or August, but for most adults (particularly adults aged ≥65 years) and for pregnant persons in the first or second trimester, vaccination during July and August should be avoided unless there is concern that vaccination later in the season might not be possible. Certain children aged 6 months through 8 years need 2 doses; these children should receive the first dose as soon as possible after vaccine is available, including during July and August. Vaccination during July and August can be considered for children of any age who need only 1 dose for the season and for pregnant persons who are in the third trimester during these months if vaccine is available. ACIP recommends that all persons aged ≥6 months who do not have contraindications receive a licensed and age-appropriate seasonal influenza vaccine. With the exception of vaccination for adults aged ≥65 years, ACIP makes no preferential recommendation for a specific vaccine when more than one licensed, recommended, and age-appropriate vaccine is available. ACIP recommends that adults aged ≥65 years preferentially receive any one of the following higher dose or adjuvanted influenza vaccines: quadrivalent high-dose inactivated influenza vaccine (HD-IIV4), quadrivalent recombinant influenza vaccine (RIV4), or quadrivalent adjuvanted inactivated influenza vaccine (aIIV4). If none of these three vaccines is available at an opportunity for vaccine administration, then any other age-appropriate influenza vaccine should be used. Primary updates to this report include the following two topics: 1) the composition of 2023–24 U.S. seasonal influenza vaccines and 2) updated recommendations regarding influenza vaccination of persons with egg allergy. First, the composition of 2023–24 U.S. influenza vaccines includes an update to the influenza A(H1N1)pdm09 component. U.S.-licensed influenza vaccines will contain HA derived from 1) an influenza A/Victoria/4897/2022 (H1N1)pdm09-like virus (for egg-based vaccines) or an influenza A/Wisconsin/67/2022 (H1N1)pdm09-like virus (for cell culture-based and recombinant vaccines); 2) an influenza A/Darwin/9/2021 (H3N2)-like virus (for egg-based vaccines) or an influenza A/Darwin/6/2021 (H3N2)-like virus (for cell culture-based and recombinant vaccines); 3) an influenza B/Austria/1359417/2021 (Victoria lineage)-like virus; and 4) an influenza B/Phuket/3073/2013 (Yamagata lineage)-like virus. Second, ACIP recommends that all persons aged ≥6 months with egg allergy should receive influenza vaccine. Any influenza vaccine (egg based or nonegg based) that is otherwise appropriate for the recipient’s age and health status can be used. It is no longer recommended that persons who have had an allergic reaction to egg involving symptoms other than urticaria should be vaccinated in an inpatient or outpatient medical setting supervised by a health care provider who is able to recognize and man ge severe allergic reactions if an egg-based vaccine is used. Egg allergy alone necessitates no additional safety measures for influenza vaccination beyond those recommended for any recipient of any vaccine, regardless of severity of previous reaction to egg. All vaccines should be administered in settings in which personnel and equipment needed for rapid recognition and treatment of acute hypersensitivity reactions are available. © (2023). All Rights Reserved. |
Effectiveness of Influenza Vaccine for Preventing Laboratory-Confirmed Influenza Hospitalizations in Immunocompromised Adults (preprint)
Hughes K , Middleton DB , Nowalk MP , Balasubramani GK , Martin ET , Gaglani M , Talbot HK , Patel MM , Ferdinands JM , Zimmerman RK , Silveira FP . medRxiv 2020 2020.10.08.20208579 Background Yearly influenza immunization is recommended for immunocompromised (IC) individuals, although immune responses are lower than that for the non-immunocompromised and the data on vaccine effectiveness (VE) in the IC is scarce. We evaluated VE against influenza-associated hospitalization among IC adults.Methods We analyzed data from adults ≥ 18 years hospitalized with acute respiratory illness (ARI) during the 2017-2018 influenza season at 10 hospitals in the United States. IC adults were identified using pre-specified case-definitions, utilizing electronic medical record data. VE was evaluated with a test-negative case-control design using multivariate logistic regression with PCR-confirmed influenza as the outcome and vaccination status as the exposure, adjusting for age, enrolling site, illness onset date, race, days from onset to specimen collection, self-reported health, and self-reported hospitalizations.Results Of 3,524 adults hospitalized with ARI, 1,210 (34.3%) had an immunocompromising condition. IC adults were more likely to be vaccinated than non-IC (69.5% vs 65.2%), and less likely to have influenza (22% vs 27.8%). The mean age did not differ among IC and non-IC (61.4 vs 60.8 years old). The overall VE against influenza hospitalization, including immunocompetent adults, was 33% (95% CI, 21% to 44%). VE among IC vs non-IC adults was lower at 5% (−29% to 31%) vs. 41% (27% to 52%) (p<0.05 for interaction term).Conclusions VE in one influenza season was very low among IC individuals. Future efforts should include evaluation of VE among the different immunocompromising conditions and whether enhanced vaccines improve the suboptimal effectiveness among the immunocompromised.Competing Interest StatementDBM has received personal fees from Sequris, Pfizer, and Sanofi Pasteur, and grants from Pfizer. JF reports non-financial support from the Institute for Influenza Epidemiology. RKZ has received grants from Sanofi Pasteur and Merck & Co. All other authors report no potential conflicts.Clinical TrialThis study was not registered in ClinicalTrials.gov because it doesn't meet NIH's definition of a clinical trial.Funding StatementThis study was funded by the CDC (cooperative agreement IP15-002). Vanderbilt also received support from CTSA award number UL1 TR002243 from the National Center for Advancing Translational Sciences.Author DeclarationsI confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.YesThe details of the IRB/oversight body that provided approval or exemption for the research described are given below:The study protocol was reviewed by the Institutional Review Board at each participating institution and CDC, as detailed below: CDC's IRB: ethical approval given University of Pittsburgh IRB: ethical approval given University of Michigan IRB: ethical approval given Baylor Scott & White Health IRB: ethical approval given Vanderbilt University IRB: ethical approval given All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived.YesI understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).YesI have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable.YesData may be made available after completion of the study. |
Evaluation of correlates of protection against influenza A(H3N2) and A(H1N1)pdm09 infection: Applications to the hospitalized patient population (preprint)
Petrie JG , Martin ET , Truscon R , Johnson E , Cheng CK , McSpadden EJ , Malosh RE , Lauring AS , Lamerato LE , Eichelberger MC , Ferdinands JM , Monto AS . bioRxiv 2018 416628 Background Influenza vaccines are important for prevention of influenza-associated hospitalization. Assessments of serologic correlates of protection can support interpretation of influenza vaccine effectiveness evaluations in hospitalized populations.Methods Serum specimens collected at admission from adults hospitalized for treatment of acute respiratory illnesses during two influenza seasons were tested in hemagglutination-inhibition (HAI) and neuraminidase-inhibition (NAI) assays. We evaluated the suitability of these specimens as proxies for pre-infection immune status, and measured associations between antibody titers and influenza vaccination and infectionResults Specimens were collected within 3 days of illness onset from 65% of participants; geometric mean titers (GMTs) did not vary by day of collection. In both seasons, vaccinated participants had higher HAI and NAI GMTs than unvaccinated participants. HAI titers against the 2014-2015 A(H3N2) vaccine strain did not correlate with protection from infection with antigenically-drifted A(H3N2) viruses that circulated that season. In contrast, higher HAI titers against the A(H1N1)pdm09 vaccine strain were associated with reduced odds of A(H1N1)pdm09 infection in 2015-2016.Conclusions Serum collected after hospital admission can be used to assess correlates of protection against influenza infection. Broader implementation of similar studies would provide an opportunity to understand the successes and shortcomings of current influenza vaccines.We thank Jin Gao and Laura Couzens for technical support and are indebted to St Jude Children’s Research Hospital for plasmids that were used to generate reassortant influenza viruses. |
Antibodies against egg- and cell-grown influenza A(H3N2) viruses in adults hospitalized during the 2017-2018 season (preprint)
Levine MZ , Martin ET , Petrie JG , Lauring AS , Holiday C , Jefferson S , Fitzsimmons WJ , Johnson E , Ferdinands JM , Monto AS . bioRxiv 2018 439471 Background The 2017-2018 US influenza season was severe with low vaccine effectiveness. Circulating A(H3N2) viruses from multiple genetic groups were antigenically similar to cell-grown vaccine strains. However, most influenza vaccines are egg-propagated.Methods Serum was collected shortly after illness onset from 15 PCR confirmed A(H3N2) infected cases and 15 uninfected (controls) hospitalized adults enrolled in an influenza vaccine effectiveness study.Geometric mean titers against egg- and cell-grown A/Hong Kong/4801/2014 A(H3N2) vaccine strains and representative circulating viruses (including A/Washington/16/2017) were determined by microneutralization (MN) assays. Independent effects of strain-specific titers on susceptibility were estimated by logistic regression.Results MN titers against egg-A/Hong Kong were significantly higher among those who were vaccinated (MN GMT: 173 vs 41; P = 0.01). However, antibody titers to cell-grown viruses were much lower in all individuals (P>0.05) regardless of vaccination. In unadjusted models, a 2-fold increase in MN titers against egg-A/Hong Kong was not significantly protective against infection (29% reduction; p=0.09), but a similar increase in cell-A/Washington titer (3C.2a2) was protective (60% reduction; p=0.02). A similar increase in egg-A/Hong Kong titer was not significantly associated with odds of infection when adjusting for MN titers against A/Washington (15% reduction; P=0.61). A 54% reduction of odds of infection was observed with a 2-fold increase in A/Washington (not significant; P=0.07), adjusted for egg-A/Hong Kong titer.Conclusion Although individuals vaccinated in 2017-2018 had high antibody titers against the egg-adapted vaccine strain, antibody responses to cell-grown circulating viruses may not be sufficient to provide protection, likely due to egg-adaptation in the vaccine.We thank Maryna Eichelberger, Hongquan Wan, Jin Gao, and Laura Couzens (Food and Drug Administration) for technical support and providing reassortant influenza viruses for use in the enzyme-linked lectin assays. St Jude Children’s Research Hospital provided plasmids that were used to generate these reassortant influenza viruses. We thank Mrs F Liaini Gross, Lauren Horner and Makeda Kay from Influenza Division, Centers for Disease Control and Prevention for technical support for virus propagation and specimen management. |
Evaluating potential impacts of a preferential vaccine recommendation for adults aged 65 and older on United States influenza burden
Morris SE , Grohskopf LA , Ferdinands JM , Reed C , Biggerstaff M . Epidemiology 2023 34 (3) 345-352 BACKGROUND: High-dose, adjuvanted, and recombinant influenza vaccines may offer improved effectiveness among older adults compared to standard-dose, unadjuvanted, inactivated vaccines. However, the Advisory Committee on Immunization Practices (ACIP) only recently recommended preferential use of these 'higher-dose or adjuvanted' vaccines. One concern was that individuals might delay or decline vaccination if a preferred vaccine is not readily available. METHODS: We mathematically model how a recommendation for preferential use of higher-dose or adjuvanted vaccines in adults ≥65 years might impact influenza burden in the United States during exemplar 'high-' and 'low-' severity seasons. We assume higher-dose or adjuvanted vaccines are more effective than standard vaccines and that such a recommendation would increase uptake of the former but could cause (i) delays in administration of additional higher-dose or adjuvanted vaccines relative to standard vaccines and/or (ii) reductions in overall coverage if individuals only offered standard vaccines forego vaccination. RESULTS: In a best-case scenario, assuming no delay or coverage reduction, a new recommendation could decrease hospitalizations and deaths in adults ≥65 years by 0-4% compared with current uptake. However, intermediate and worst-case scenarios, with assumed delays of 3 or 6 weeks and/or 10 or 20% reductions in coverage, included projections in which hospitalizations and deaths increased by over 7%. CONCLUSIONS: We estimate that increased use of higher-dose or adjuvanted vaccines could decrease influenza burden in adults ≥65 in the United States provided there is timely and adequate access to these vaccines, and that standard vaccines are administered when they are unavailable. |
Prevalence and clinical outcomes of respiratory syncytial virus versus influenza in adults hospitalized with acute respiratory illness from a prospective multicenter study
Begley KM , Monto AS , Lamerato LE , Malani AN , Lauring AS , Talbot HK , Gaglani M , McNeal T , Silveira FP , Zimmerman RK , Middleton DB , Ghamande S , Murthy K , Kim L , Ferdinands JM , Patel MM , Martin ET . Clin Infect Dis 2023 BACKGROUND: Current understanding of severe RSV infections in adults is limited by clinical under-recognition. We compared the prevalence, clinical characteristics, and outcomes of RSV infections vs influenza in adults hospitalized with acute respiratory illnesses in a prospective national surveillance network. METHODS: Hospitalized adults who met a standardized ARI case definition were prospectively enrolled across three respiratory seasons from hospitals participating across all sites of the U.S. Hospitalized Adult Influenza Vaccine Effectiveness Network (HAIVEN, 2016-2019). All participants were tested for RSV and influenza by RT-PCR. Multivariable logistic regression was used to test associations between laboratory-confirmed infection and characteristics and clinical outcomes. RESULTS: Among 10,311 hospitalized adults, 6% tested positive for RSV (n=622), 18.8% positive for influenza (n=1,940), and 75.1% negative for RSV and influenza (n=7,749). Congestive Heart Failure (CHF) or Chronic Obstructive Pulmonary Disease (COPD) was more frequent among adults with RSV than influenza (CHF: 37.3% vs. 28.8%, p<0.0001; COPD: 47.6% vs. 35.8%, p<0.0001). Patients with RSV more frequently had longer admissions [OR=1.38 (95% CI: 1.06-1.80) for stays >one week] and mechanical ventilation [OR=1.45 (95% CI: 1.09-1.93)] compared with influenza, but not compared to the influenza negative group [OR=1.03 (95% CI: 0.82-1.28); OR=1.17 (0.91-1.49), respectively.]. CONCLUSIONS: The prevalence of RSV across three recent respiratory illness seasons was considerable. Our findings suggest those with RSV might incur worse outcomes than influenza in hospitalized adults and frequently have pre-existing cardiopulmonary conditions. This study informs future vaccination strategies and underscores a need for RSV surveillance among adults experiencing severe ARI. |
Waning of vaccine effectiveness against moderate and severe covid-19 among adults in the US from the VISION network: test negative, case-control study.
Ferdinands JM , Rao S , Dixon BE , Mitchell PK , DeSilva MB , Irving SA , Lewis N , Natarajan K , Stenehjem E , Grannis SJ , Han J , McEvoy C , Ong TC , Naleway AL , Reese SE , Embi PJ , Dascomb K , Klein NP , Griggs EP , Liao IC , Yang DH , Fadel WF , Grisel N , Goddard K , Patel P , Murthy K , Birch R , Valvi NR , Arndorfer J , Zerbo O , Dickerson M , Raiyani C , Williams J , Bozio CH , Blanton L , Link-Gelles R , Barron MA , Gaglani M , Thompson MG , Fireman B . BMJ 2022 379 e072141 OBJECTIVE: To estimate the effectiveness of mRNA vaccines against moderate and severe covid-19 in adults by time since second, third, or fourth doses, and by age and immunocompromised status. DESIGN: Test negative case-control study. SETTING: Hospitals, emergency departments, and urgent care clinics in 10 US states, 17 January 2021 to 12 July 2022. PARTICIPANTS: 893 461 adults (≥18 years) admitted to one of 261 hospitals or to one of 272 emergency department or 119 urgent care centers for covid-like illness tested for SARS-CoV-2. MAIN OUTCOME MEASURES: The main outcome was waning of vaccine effectiveness with BNT162b2 (Pfizer-BioNTech) or mRNA-1273 (Moderna) vaccine during the omicron and delta periods, and the period before delta was dominant using logistic regression conditioned on calendar week and geographic area while adjusting for age, race, ethnicity, local virus circulation, immunocompromised status, and likelihood of being vaccinated. RESULTS: 45 903 people admitted to hospital with covid-19 (cases) were compared with 213 103 people with covid-like illness who tested negative for SARS-CoV-2 (controls), and 103 287 people admitted to emergency department or urgent care with covid-19 (cases) were compared with 531 168 people with covid-like illness who tested negative for SARS-CoV-2. In the omicron period, vaccine effectiveness against covid-19 requiring admission to hospital was 89% (95% confidence interval 88% to 90%) within two months after dose 3 but waned to 66% (63% to 68%) by four to five months. Vaccine effectiveness of three doses against emergency department or urgent care visits was 83% (82% to 84%) initially but waned to 46% (44% to 49%) by four to five months. Waning was evident in all subgroups, including young adults and individuals who were not immunocompromised; although waning was morein people who were immunocompromised. Vaccine effectiveness increased among most groups after a fourth dose in whom this booster was recommended. CONCLUSIONS: Effectiveness of mRNA vaccines against moderate and severe covid-19 waned with time after vaccination. The findings support recommendations for a booster dose after a primary series and consideration of additional booster doses. |
Prevention and control of seasonal influenza with vaccines: Recommendations of the Advisory Committee on Immunization Practices - United States, 2022-23 Influenza Season
Grohskopf LA , Blanton LH , Ferdinands JM , Chung JR , Broder KR , Talbot HK , Morgan RL , Fry AM . MMWR Recomm Rep 2022 71 (1) 1-28 THIS REPORT UPDATES THE 2021-22 RECOMMENDATIONS OF THE ADVISORY COMMITTEE ON IMMUNIZATION PRACTICES (ACIP) CONCERNING THE USE OF SEASONAL INFLUENZA VACCINES IN THE UNITED STATES: (MMWR Recomm Rep 2021;70[No. RR-5]:1-24). Routine annual influenza vaccination is recommended for all persons aged ≥6 months who do not have contraindications. For each recipient, a licensed and age-appropriate vaccine should be used. With the exception of vaccination for adults aged ≥65 years, ACIP makes no preferential recommendation for a specific vaccine when more than one licensed, recommended, and age-appropriate vaccine is available. All seasonal influenza vaccines expected to be available in the United States for the 2022-23 season are quadrivalent, containing hemagglutinin (HA) derived from one influenza A(H1N1)pdm09 virus, one influenza A(H3N2) virus, one influenza B/Victoria lineage virus, and one influenza B/Yamagata lineage virus. Inactivated influenza vaccines (IIV4s), recombinant influenza vaccine (RIV4), and live attenuated influenza vaccine (LAIV4) are expected to be available. Trivalent influenza vaccines are no longer available, but data that involve these vaccines are included for reference. INFLUENZA VACCINES MIGHT BE AVAILABLE AS EARLY AS JULY OR AUGUST, BUT FOR MOST PERSONS WHO NEED ONLY 1 DOSE OF INFLUENZA VACCINE FOR THE SEASON, VACCINATION SHOULD IDEALLY BE OFFERED DURING SEPTEMBER OR OCTOBER. HOWEVER, VACCINATION SHOULD CONTINUE AFTER OCTOBER AND THROUGHOUT THE SEASON AS LONG AS INFLUENZA VIRUSES ARE CIRCULATING AND UNEXPIRED VACCINE IS AVAILABLE. FOR MOST ADULTS (PARTICULARLY ADULTS AGED ≥65 YEARS) AND FOR PREGNANT PERSONS IN THE FIRST OR SECOND TRIMESTER, VACCINATION DURING JULY AND AUGUST SHOULD BE AVOIDED UNLESS THERE IS CONCERN THAT VACCINATION LATER IN THE SEASON MIGHT NOT BE POSSIBLE. CERTAIN CHILDREN AGED 6 MONTHS THROUGH 8 YEARS NEED 2 DOSES; THESE CHILDREN SHOULD RECEIVE THE FIRST DOSE AS SOON AS POSSIBLE AFTER VACCINE IS AVAILABLE, INCLUDING DURING JULY AND AUGUST. VACCINATION DURING JULY AND AUGUST CAN BE CONSIDERED FOR CHILDREN OF ANY AGE WHO NEED ONLY 1 DOSE FOR THE SEASON AND FOR PREGNANT PERSONS WHO ARE IN THE THIRD TRIMESTER IF VACCINE IS AVAILABLE DURING THOSE MONTHS: UPDATES DESCRIBED IN THIS REPORT REFLECT DISCUSSIONS DURING PUBLIC MEETINGS OF ACIP THAT WERE HELD ON OCTOBER 20, 2021; JANUARY 12, 2022; FEBRUARY 23, 2022; AND JUNE 22, 2022. PRIMARY UPDATES TO THIS REPORT INCLUDE THE FOLLOWING THREE TOPICS: 1) THE COMPOSITION OF 2022-23 U.S. SEASONAL INFLUENZA VACCINES; 2) UPDATES TO THE DESCRIPTION OF INFLUENZA VACCINES EXPECTED TO BE AVAILABLE FOR THE 2022-23 SEASON, INCLUDING ONE INFLUENZA VACCINE LABELING CHANGE THAT OCCURRED AFTER THE PUBLICATION OF THE 2021-22 ACIP INFLUENZA RECOMMENDATIONS; AND 3) UPDATES TO THE RECOMMENDATIONS CONCERNING VACCINATION OF ADULTS AGED ≥65 YEARS. FIRST, THE COMPOSITION OF 2022-23 U.S. INFLUENZA VACCINES INCLUDES UPDATES TO THE INFLUENZA A(H3N2) AND INFLUENZA B/VICTORIA LINEAGE COMPONENTS. U.S.-LICENSED INFLUENZA VACCINES WILL CONTAIN HA DERIVED FROM AN INFLUENZA A/VICTORIA/2570/2019 (H1N1)PDM09-LIKE VIRUS (FOR EGG-BASED VACCINES) OR AN INFLUENZA A/WISCONSIN/588/2019 (H1N1)PDM09-LIKE VIRUS (FOR CELL CULTURE-BASED OR RECOMBINANT VACCINES); AN INFLUENZA A/DARWIN/9/2021 (H3N2)-LIKE VIRUS (FOR EGG-BASED VACCINES) OR AN INFLUENZA A/DARWIN/6/2021 (H3N2)-LIKE VIRUS (FOR CELL CULTURE-BASED OR RECOMBINANT VACCINES); AN INFLUENZA B/AUSTRIA/1359417/2021 (VICTORIA LINEAGE)-LIKE VIRUS; AND AN INFLUENZA B/PHUKET/3073/2013 (YAMAGATA LINEAGE)-LIKE VIRUS. SECOND, THE APPROVED AGE INDICATION FOR THE CELL CULTURE-BASED INACTIVATED INFLUENZA VACCINE, FLUCELVAX QUADRIVALENT (CCIIV4), WAS CHANGED IN OCTOBER 2021 FROM ≥2 YEARS TO ≥6 MONTHS. THIRD, RECOMMENDATIONS FOR VACCINATION OF ADULTS AGED ≥65 YEARS HAVE BEEN MODIFIED. ACIP RECOMMENDS THAT ADULTS AGED ≥65 YEARS PREFERENTIALLY RECEIVE ANY ONE OF THE FOLLOWING HIGHER DOSE OR ADJUVANTED INFLUENZA VACCINES: QUADRIVALENT HIGH-DOSE INACTIVATED INFLUENZA VACCINE (HD-IIV4), QUADRIVALENT RECOMBINANT INFLUENZA VACCINE (RIV4), OR QUADRIVALENT ADJUVANTED INACTIVATED INFLUENZA VACCINE (AIIV4). IF NONE OF THESE THREE VACCINES IS AVAILABLE AT AN OPPORTUNITY FOR VACCINE ADMINISTRATION, THEN ANY OTHER AGE-APPROPRIATE INFLUENZA VACCINE SHOULD BE USED: THIS REPORT FOCUSES ON RECOMMENDATIONS FOR THE USE OF VACCINES FOR THE PREVENTION AND CONTROL OF SEASONAL INFLUENZA DURING THE 2022-23 INFLUENZA SEASON IN THE UNITED STATES. A BRIEF SUMMARY OF THE RECOMMENDATIONS AND A LINK TO THE MOST RECENT BACKGROUND DOCUMENT CONTAINING ADDITIONAL INFORMATION ARE AVAILABLE AT: https://www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/flu.html. These recommendations apply to U.S.-licensed influenza vaccines used according to Food and Drug Administration-licensed indications. Updates and other information are available from CDC's influenza website (https://www.cdc.gov/flu). Vaccination and health care providers should check this site periodically for additional information. |
Influence of disease attenuation on relative influenza vaccine effectiveness by vaccine type
Ferdinands JM , Patel M . Vaccine 2022 40 (19) 2797-2801 Benefit conferred by "enhanced" influenza vaccines is often measured by relative vaccine effectiveness, (rVE), which compares disease risk among groups of people who received alternative vaccines. Differences in attenuation of illness severity by vaccine types could manifest as differences in rVE. Using a simulated VE study and cohort of adults aged ≥ 65 years, we examined how rVE varied with assumptions about attenuation of disease severity conferred by standard and enhanced vaccines and how this variation could lead to differing estimates of rVE for prevention of moderate (i.e., outpatient) versus severe (i.e., inpatient) influenza illness. We found that if enhanced vaccines attenuated severe illness more than moderate illness, then rVE observed against severe disease could be higher than rVE observed against moderate disease. Thus, if differences in disease attenuation by vaccine type occurs, estimates of rVE may vary for influenza outcomes of differing levels of severity. |
Waning 2-Dose and 3-Dose Effectiveness of mRNA Vaccines Against COVID-19-Associated Emergency Department and Urgent Care Encounters and Hospitalizations Among Adults During Periods of Delta and Omicron Variant Predominance - VISION Network, 10 States, August 2021-January 2022.
Ferdinands JM , Rao S , Dixon BE , Mitchell PK , DeSilva MB , Irving SA , Lewis N , Natarajan K , Stenehjem E , Grannis SJ , Han J , McEvoy C , Ong TC , Naleway AL , Reese SE , Embi PJ , Dascomb K , Klein NP , Griggs EP , Konatham D , Kharbanda AB , Yang DH , Fadel WF , Grisel N , Goddard K , Patel P , Liao IC , Birch R , Valvi NR , Reynolds S , Arndorfer J , Zerbo O , Dickerson M , Murthy K , Williams J , Bozio CH , Blanton L , Verani JR , Schrag SJ , Dalton AF , Wondimu MH , Link-Gelles R , Azziz-Baumgartner E , Barron MA , Gaglani M , Thompson MG , Fireman B . MMWR Morb Mortal Wkly Rep 2022 71 (7) 255-263 CDC recommends that all persons aged ≥12 years receive a booster dose of COVID-19 mRNA vaccine ≥5 months after completion of a primary mRNA vaccination series and that immunocompromised persons receive a third primary dose.* Waning of vaccine protection after 2 doses of mRNA vaccine has been observed during the period of the SARS-CoV-2 B.1.617.2 (Delta) variant predominance(†) (1-5), but little is known about durability of protection after 3 doses during periods of Delta or SARS-CoV-2 B.1.1.529 (Omicron) variant predominance. A test-negative case-control study design using data from eight VISION Network sites(§) examined vaccine effectiveness (VE) against COVID-19 emergency department/urgent care (ED/UC) visits and hospitalizations among U.S. adults aged ≥18 years at various time points after receipt of a second or third vaccine dose during two periods: Delta variant predominance and Omicron variant predominance (i.e., periods when each variant accounted for ≥50% of sequenced isolates).(¶) Persons categorized as having received 3 doses included those who received a third dose in a primary series or a booster dose after a 2 dose primary series (including the reduced-dosage Moderna booster). The VISION Network analyzed 241,204 ED/UC encounters** and 93,408 hospitalizations across 10 states during August 26, 2021-January 22, 2022. VE after receipt of both 2 and 3 doses was lower during the Omicron-predominant than during the Delta-predominant period at all time points evaluated. During both periods, VE after receipt of a third dose was higher than that after a second dose; however, VE waned with increasing time since vaccination. During the Omicron period, VE against ED/UC visits was 87% during the first 2 months after a third dose and decreased to 66% among those vaccinated 4-5 months earlier; VE against hospitalizations was 91% during the first 2 months following a third dose and decreased to 78% ≥4 months after a third dose. For both Delta- and Omicron-predominant periods, VE was generally higher for protection against hospitalizations than against ED/UC visits. All eligible persons should remain up to date with recommended COVID-19 vaccinations to best protect against COVID-19-associated hospitalizations and ED/UC visits. |
Interpretation of Relative Efficacy and Effectiveness for Influenza Vaccines
Lewis NM , Chung JR , Uyeki TM , Grohskopf L , Ferdinands JM , Patel MM . Clin Infect Dis 2021 75 (1) 170-175 Relative vaccine effectiveness (rVE) are metrics commonly reported to compare absolute VE (aVE) of two vaccine products. Estimates of rVE for enhanced influenza vaccines (eIV) vs. standard inactivated influenza vaccine (IIV) have been assessed across different seasons, influenza-specific endpoints, and nonspecific endpoints (e.g., all-cause cardiovascular hospitalizations). To illustrate the challenges of comparability across studies, we conducted a scenario analysis to evaluate the effects of varying absolute VE (aVE) of IIV (i.e., as compared with placebo) on the interpretation of rVE of eIV vs IIV. We show that estimates of rVE might not be comparable across studies because additional benefits commensurate with a given estimate of rVE are dependent on the aVE for the comparator vaccine, which can depend on factors such as host response to vaccine, virus type, and clinical endpoint evaluated. These findings have implications for interpretation of rVE across studies and for sample size considerations in future trials. |
Clinical Influenza Testing Practices in Hospitalized Children at United States Medical Centers, 2015-2018
Tenforde MW , Campbell AP , Michaels MG , Harrison CJ , Klein EJ , Englund JA , Selvarangan R , Halasa NB , Stewart LS , Weinberg GA , Williams JV , Szilagyi PG , Staat MA , Boom JA , Sahni LC , Singer MN , Azimi PH , Zimmerman RK , McNeal MM , Talbot HK , Monto AS , Martin ET , Gaglani M , Silveira FP , Middleton DB , Ferdinands JM , Rolfes MA . J Pediatric Infect Dis Soc 2021 11 (1) 5-8 At nine US hospitals that enrolled children hospitalized with acute respiratory illness (ARI) during 2015-2016 through 2017-2018 influenza seasons, 50% of children with ARI received clinician-initiated testing for influenza and 35% of cases went undiagnosed due to lack of clinician-initiated testing. Marked heterogeneity in testing practice was observed across sites. |
Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices, United States, 2021-22 Influenza Season.
Grohskopf LA , Alyanak E , Ferdinands JM , Broder KR , Blanton LH , Talbot HK , Fry AM . MMWR Recomm Rep 2021 70 (5) 1-28 This report updates the 2020-21 recommendations of the Advisory Committee on Immunization Practices (ACIP) regarding the use of seasonal influenza vaccines in the United States (MMWR Recomm Rep 2020;69[No. RR-8]). Routine annual influenza vaccination is recommended for all persons aged ≥6 months who do not have contraindications. For each recipient, a licensed and age-appropriate vaccine should be used. ACIP makes no preferential recommendation for a specific vaccine when more than one licensed, recommended, and age-appropriate vaccine is available. During the 2021-22 influenza season, the following types of vaccines are expected to be available: inactivated influenza vaccines (IIV4s), recombinant influenza vaccine (RIV4), and live attenuated influenza vaccine (LAIV4).The 2021-22 influenza season is expected to coincide with continued circulation of SARS-CoV-2, the virus that causes COVID-19. Influenza vaccination of persons aged ≥6 months to reduce prevalence of illness caused by influenza will reduce symptoms that might be confused with those of COVID-19. Prevention of and reduction in the severity of influenza illness and reduction of outpatient visits, hospitalizations, and intensive care unit admissions through influenza vaccination also could alleviate stress on the U.S. health care system. Guidance for vaccine planning during the pandemic is available at https://www.cdc.gov/vaccines/pandemic-guidance/index.html. Recommendations for the use of COVID-19 vaccines are available at https://www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/covid-19.html, and additional clinical guidance is available at https://www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html.Updates described in this report reflect discussions during public meetings of ACIP that were held on October 28, 2020; February 25, 2021; and June 24, 2021. Primary updates to this report include the following six items. First, all seasonal influenza vaccines available in the United States for the 2021-22 season are expected to be quadrivalent. Second, the composition of 2021-22 U.S. influenza vaccines includes updates to the influenza A(H1N1)pdm09 and influenza A(H3N2) components. U.S.-licensed influenza vaccines will contain hemagglutinin derived from an influenza A/Victoria/2570/2019 (H1N1)pdm09-like virus (for egg-based vaccines) or an influenza A/Wisconsin/588/2019 (H1N1)pdm09-like virus (for cell culture-based and recombinant vaccines), an influenza A/Cambodia/e0826360/2020 (H3N2)-like virus, an influenza B/Washington/02/2019 (Victoria lineage)-like virus, and an influenza B/Phuket/3073/2013 (Yamagata lineage)-like virus. Third, the approved age indication for the cell culture-based inactivated influenza vaccine, Flucelvax Quadrivalent (ccIIV4), has been expanded from ages ≥4 years to ages ≥2 years. Fourth, discussion of administration of influenza vaccines with other vaccines includes considerations for coadministration of influenza vaccines and COVID-19 vaccines. Providers should also consult current ACIP COVID-19 vaccine recommendations and CDC guidance concerning coadministration of these vaccines with influenza vaccines. Vaccines that are given at the same time should be administered in separate anatomic sites. Fifth, guidance concerning timing of influenza vaccination now states that vaccination soon after vaccine becomes available can be considered for pregnant women in the third trimester. As previously recommended, children who need 2 doses (children aged 6 months through 8 years who have never received influenza vaccine or who have not previously received a lifetime total of ≥2 doses) should receive their first dose as soon as possible after vaccine becomes available to allow the second dose (which must be administered ≥4 weeks later) to be received by the end of October. For nonpregnant adults, vaccination in July and August should be avoided unless there is concern that later vaccination might not be possible. Sixth, contraindications and precautions to the use of ccIIV4 and RIV4 have been modified, specifically with regard to persons with a history of severe allergic reaction (e.g., anaphylaxis) to an influenza vaccine. A history of a severe allergic reaction to a previous dose of any egg-based IIV, LAIV, or RIV of any valency is a precaution to use of ccIIV4. A history of a severe allergic reaction to a previous dose of any egg-based IIV, ccIIV, or LAIV of any valency is a precaution to use of RIV4. Use of ccIIV4 and RIV4 in such instances should occur in an inpatient or outpatient medical setting under supervision of a provider who can recognize and manage a severe allergic reaction; providers can also consider consulting with an allergist to help identify the vaccine component responsible for the reaction. For ccIIV4, history of a severe allergic reaction (e.g., anaphylaxis) to any ccIIV of any valency or any component of ccIIV4 is a contraindication to future use of ccIIV4. For RIV4, history of a severe allergic reaction (e.g., anaphylaxis) to any RIV of any valency or any component of RIV4 is a contraindication to future use of RIV4. This report focuses on recommendations for the use of vaccines for the prevention and control of seasonal influenza during the 2021-22 influenza season in the United States. A brief summary of the recommendations and a link to the most recent Background Document containing additional information are available at https://www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/flu.html. These recommendations apply to U.S.-licensed influenza vaccines used according to Food and Drug Administration-licensed indications. Updates and other information are available from CDC's influenza website (https://www.cdc.gov/flu); vaccination and health care providers should check this site periodically for additional information. |
Vaccine effectiveness against acute respiratory illness hospitalizations for influenza-associated pneumonia during the 2015-2016 to 2017-2018 seasons, US Hospitalized Adult Influenza Vaccine Effectiveness Network (HAIVEN)
Ghamande S , Shaver C , Murthy K , Raiyani C , White HD , Lat T , Arroliga AC , Wyatt D , Talbot HK , Martin ET , Monto AS , Zimmerman RK , Middleton DB , Silveira FP , Ferdinands JM , Patel MM , Gaglani M . Clin Infect Dis 2021 74 (8) 1329-1337 BACKGROUND: Evidence for vaccine effectiveness (VE) against influenza-associated pneumonia has varied by season, location, and strain. We estimate VE against hospitalization for radiographically identified influenza-associated pneumonia during 2015-2016 to 2017-2018 seasons in the US Hospitalized Adult Influenza Vaccine Effectiveness Network (HAIVEN). METHODS: Among adults aged ≥18 years admitted to 10 US hospitals for acute respiratory illness (ARI), clinician-investigators used keywords from reports of chest imaging performed during 3 days around hospital admission to assign a diagnosis of 'definite/probable pneumonia'. We used a test-negative design to estimate VE against hospitalization for radiographically identified laboratory-confirmed influenza-associated pneumonia, comparing RT-PCR confirmed influenza cases with test-negative subjects. Influenza vaccination status was documented in immunization records or self-reported, including date and location. Multivariable logistic regression models were used to adjust for age, site, season, calendar-time, and other factors. RESULTS: Of 4,843 adults hospitalized with ARI included in the primary analysis, 266 (5.5%) had 'definite/probable pneumonia' and confirmed influenza. Adjusted VE against hospitalization for any radiographically confirmed influenza-associated pneumonia was 38% (95% confidence interval [CI]): 17%-53%); by type/subtype, it was 74% (95% CI: 52%-87%), influenza A (H1N1)pdm09; 25% (-15% to 50%), A (H3N2); and 23% (95% CI: -32% to 54%), influenza B. Adjusted VE against intensive care for any influenza was 57% (95% CI, 19%-77%). CONCLUSIONS: Influenza vaccination was modestly effective among adults in preventing hospitalizations and the need for intensive care associated with influenza pneumonia. VE was significantly higher against A (H1N1)pdm09 and was low against A (H3N2) and B. |
Does influenza vaccination attenuate the severity of breakthrough infections A narrative review and recommendations for further research
Ferdinands JM , Thompson MG , Blanton L , Spencer S , Grant L , Fry AM . Vaccine 2021 39 (28) 3678-3695 The effect of influenza vaccination on influenza severity remains uncertain. We reviewed the literature for evidence to inform the question of whether influenza illness is less severe among individuals who received influenza vaccination compared with individuals with influenza illness who were unvaccinated prior to their illnesses. We conducted a narrative review to identify published findings comparing severity of influenza outcomes by vaccination status among community-dwelling adults and children ≥ 6 months of age with laboratory-confirmed influenza illness. When at least four effect estimates of the same type (e.g., odds ratio) were available for a specific outcome and age category (children versus adults), data were pooled with meta-analysis to generate a summary effect estimate. We identified 38 published articles reporting ≥ 1 association between influenza vaccination status and one of 21 indicators of severity of influenza illness among individuals with laboratory-confirmed influenza. Study methodologies and effect estimates were highly heterogenous, with only five severity indicators meeting criteria for calculating a combined effect. Among eight studies, influenza vaccination was associated with 26% reduction in odds of ICU admission among adults with influenza-associated hospitalization (OR = 0.74, 95% CI 0.58, 0.93). Among five studies of adults with influenza-associated hospitalization, vaccinated patients had 31% reduced risk of death compared with unvaccinated patients (OR = 0.69, 95% CI 0.52, 0.92). Among four studies of children with influenza virus infection, vaccination was associated with an estimated 45% reduction in the odds of manifesting fever (OR = 0.55, 95% CI 0.42, 0.71). Vaccination was not significantly associated with receiving a clinical diagnosis of pneumonia among adults hospitalized with influenza (OR = 0.92, 95% CI 0.82, 1.04) or with risk of hospitalization following outpatient influenza illness among adults (OR = 0.60, 95% CI 0.28, 1.28). Overall, our findings support the hypothesis that influenza vaccination may attenuate the course of disease among individuals with breakthrough influenza virus infection. |
Modeling the impacts of clinical influenza testing on influenza vaccine effectiveness estimates
Feldstein LR , Ferdinands JM , Self WH , Randolph AG , Aboodi M , Baughman AH , Brown SM , Exline MC , Files DC , Gibbs K , Ginde AA , Gong MN , Grijalva CG , Halasa N , Khan A , Lindsell CJ , Newhams M , Peltan ID , Prekker ME , Rice TW , Shapiro NI , Steingrub J , Talbot HK , Halloran ME , Patel M . J Infect Dis 2021 224 (12) 2035-2042 BACKGROUND: Test-negative design studies for evaluating influenza vaccine effectiveness (VE) enroll patients with acute respiratory infection. Enrollment typically occurs before influenza status is determined, resulting in over-enrollment of influenza-negative patients. With availability of rapid and accurate molecular clinical testing, influenza status could be ascertained prior to enrollment, thus improving study efficiency. We estimate potential biases in VE when using clinical testing. METHODS: We simulate data assuming 60% vaccinated, 25% of those vaccinated are influenza positive, and VE of 50%. We show the effect on VE in five scenarios. RESULTS: VE is affected only when clinical testing preferentially targets patients based on both vaccination and influenza status. VE is overestimated by 10% if non-testing occurs in 39% of vaccinated influenza-positive patients and 24% of others; and if non-testing occurs in 8% of unvaccinated influenza-positive patients and 27% of others. VE is underestimated by 10% if non-testing occurs in 32% of unvaccinated influenza-negative patients and 18% of others. CONCLUSIONS: Although differential clinical testing by vaccine receipt and influenza positivity may produce errors in estimated VE, bias in testing would have to be substantial and overall proportion of patients tested would have to be small to result in a meaningful difference in VE. |
Coronavirus disease 2019 (COVID-19) Versus Influenza in Hospitalized Adult Patients in the United States: Differences in Demographic and Severity Indicators.
Talbot HK , Martin ET , Gaglani M , Middleton DB , Ghamande S , Silveira FP , Murthy K , Zimmerman RK , Trabue CH , Olson SM , Petrie JG , Ferdinands JM , Patel MM , Monto AS . Clin Infect Dis 2021 73 (12) 2240-2247 BACKGROUND: Novel coronavirus disease 2019 (COVID-19) is frequently compared with influenza. The Hospitalized Adult Influenza Vaccine Effectiveness Network (HAIVEN) conducts studies on the etiology and characteristics of U.S. hospitalized adults with influenza. It began enrolling patients with COVID-19 hospitalizations in March 2020. Patients with influenza were compared with those with COVID-19 in the first months of the U.S. epidemic. METHODS: Adults aged ≥ 18 years admitted to hospitals in 4 sites with acute respiratory illness were tested by real-time reverse transcription polymerase chain reaction for influenza and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus causing COVID-19. Demographic and illness characteristics were collected for influenza illnesses during 3 seasons 2016-2019. Similar data were collected on COVID-19 cases admitted before June 19, 2020. RESULTS: Age groups hospitalized with COVID-19 (n = 914) were similar to those admitted with influenza (n = 1937); 80% of patients with influenza and 75% of patients with COVID-19 were aged ≥50 years. Deaths from COVID-19 that occurred in younger patients were less often related to underlying conditions. White non-Hispanic persons were overrepresented in influenza (64%) compared with COVID-19 hospitalizations (37%). Greater severity and complications occurred with COVID-19 including more ICU admissions (AOR = 15.3 [95% CI: 11.6, 20.3]), ventilator use (AOR = 15.6 [95% CI: 10.7, 22.8]), 7 additional days of hospital stay in those discharged alive, and death during hospitalization (AOR = 19.8 [95% CI: 12.0, 32.7]). CONCLUSIONS: While COVID-19 can cause a respiratory illness like influenza, it is associated with significantly greater severity of illness, longer hospital stays, and higher in-hospital deaths. |
Waning vaccine effectiveness against influenza-associated hospitalizations among adults, 2015-2016 to 2018-2019, US Hospitalized Adult Influenza Vaccine Effectiveness Network
Ferdinands JM , Gaglani M , Martin ET , Monto AS , Middleton D , Silveira F , Talbot HK , Zimmerman R , Patel M . Clin Infect Dis 2021 73 (4) 726-729 We observed decreased effectiveness of influenza vaccine with increasing time since vaccination for prevention of influenza A(H3N2), influenza A(H1N1)pdm09, and influenza B(Yamagata)-associated hospitalizations among adults. Maximum VE was observed shortly after vaccination, followed by an absolute decline in VE of about 8 to 9% per month post-vaccination. |
Effectiveness of influenza vaccine for preventing laboratory-confirmed influenza hospitalizations in immunocompromised adults
Hughes K , Middleton DB , Nowalk MP , Balasubramani GK , Martin ET , Gaglani M , Talbot HK , Patel MM , Ferdinands JM , Zimmerman RK , Silveira FP . Clin Infect Dis 2021 73 (11) e4353-e4360 BACKGROUND: Yearly influenza immunization is recommended for immunocompromised (IC) individuals, although immune responses are lower than that for the non-immunocompromised and the data on vaccine effectiveness (VE) in the IC is scarce. We evaluated VE against influenza-associated hospitalization among IC adults. METHODS: We analyzed data from adults ≥ 18 years hospitalized with acute respiratory illness (ARI) during the 2017-2018 influenza season at 10 hospitals in the United States. IC adults were identified using pre-specified case-definitions, utilizing electronic medical record data. VE was evaluated with a test-negative case-control design using multivariable logistic regression with PCR-confirmed influenza as the outcome and vaccination status as the exposure, adjusting for age, enrolling site, illness onset date, race, days from onset to specimen collection, self-reported health, and self-reported hospitalizations. RESULTS: Of 3,524 adults hospitalized with ARI, 1,210 (34.3%) had an immunocompromising condition. IC adults were more likely to be vaccinated than non-IC (69.5% vs 65.2%), and less likely to have influenza (22% vs 27.8%). The mean age did not differ among IC and non-IC (61.4 vs 60.8 years old). The overall VE against influenza hospitalization, including immunocompetent adults, was 33% (95% CI, 21% to 44%). VE among IC vs non-IC adults was lower at 5% (-29% to 31%) vs. 41% (27% to 52%) (p<0.05 for interaction term). CONCLUSIONS: VE in one influenza season was very low among IC individuals. Future efforts should include evaluation of VE among the different immunocompromising conditions and whether enhanced vaccines improve the suboptimal effectiveness among the immunocompromised. |
Vaccine effectiveness against influenza-associated hospitalizations among adults, 2018-2019, US Hospitalized Adult Influenza Vaccine Effectiveness Network
Ferdinands JM , Gaglani M , Ghamande S , Martin ET , Middleton D , Monto AS , Silveira F , Talbot HK , Zimmerman R , Smith ER , Patel M . J Infect Dis 2020 224 (1) 151-163 We estimated vaccine effectiveness for prevention of influenza-associated hospitalizations among adults during the 2018-2019 influenza season. Adults admitted with acute respiratory illness to 14 hospitals of the US Hospitalized Adult Influenza Vaccine Effectiveness Network and testing positive for influenza were cases; patients testing negative were controls. Vaccine effectiveness was estimated using logistic regression and inverse probability of treatment weighting. We analyzed data from 2863 patients with mean age of 63 years. Adjusted VE against influenza A(H1N1)pdm09-associated hospitalization was 51% (95%CI 25, 68). Adjusted VE against influenza A(H3N2) virus-associated hospitalization was -2% (95%CI -65, 37) and differed significantly by age, with VE of -130% (95% CI -374, -27) among adults 18 to ≤56 years of age. Although vaccination halved the risk of influenza-A(H1N1)pdm09-associated hospitalizations, it conferred no protection against influenza A(H3N2)-associated hospitalizations. We observed negative VE for young-and middle-aged adults but cannot exclude residual confounding as a potential explanation. |
Influenza vaccine effectiveness against hospitalization in the United States, 2019-2020.
Tenforde MW , Talbot HK , Trabue CH , Gaglani M , McNeal TM , Monto AS , Martin ET , Zimmerman RK , Silveira F , Middleton DB , Olson SM , Garten Kondor RJ , Barnes JR , Ferdinands JM , Patel MM . J Infect Dis 2020 224 (5) 813-820 BACKGROUND: Influenza causes significant morbidity and mortality and stresses hospital resources during periods of increased circulation. We evaluated the effectiveness of the 2019-2020 influenza vaccine against influenza-associated hospitalizations in the United States. METHODS: We included adults hospitalized with acute respiratory illness at 14 hospitals and tested for influenza viruses by reserve transcription polymerase chain reaction. Vaccine effectiveness (VE) was estimated by comparing the odds of current-season influenza vaccination in test-positive influenza cases versus test-negative controls, adjusting for confounders. VE was stratified by age and major circulating influenza types along with A(H1N1)pdm09 genetic subgroups. RESULTS: 3116 participants were included, including 18% (553) influenza-positive cases. Median age was 63 years. Sixty-seven percent (2079) received vaccination. Overall adjusted VE against influenza viruses was 41% (95% confidence interval [CI]: 27-52). VE against A(H1N1)pdm09 viruses was 40% (95% CI: 24-53) and 33% against B viruses (95% CI: 0-56). Of the two major A(H1N1)pdm09 subgroups (representing 90% of sequenced H1N1 viruses), VE against one group (5A+187A,189E) was 59% (95% CI: 34-75) whereas no significant VE was observed against the other group (5A+156K) [-1%, 95% CI: -61-37]. CONCLUSIONS: In a primarily older population, influenza vaccination was associated with a 41% reduction in risk of hospitalized influenza illness. |
Low influenza vaccine effectiveness against A(H3N2) associated hospitalizations in the 2016-2017 and 2017-2018 seasons of the Hospitalized Adult Influenza Vaccine Effectiveness Network (HAIVEN)
Martin ET , Cheng C , Petrie JG , Alyanak E , Gaglani M , Middleton DB , Ghamande S , Silveira FP , Murthy K , Zimmerman RK , Monto AS , Trabue C , Talbot HK , Ferdinands JM . J Infect Dis 2020 223 (12) 2062-2071 INTRODUCTION: The 2016-2017 and 2017-2018 influenza seasons were notable for high number of hospitalizations for influenza A(H3N2) despite vaccine and circulating strain match. METHODS: We evaluated vaccine effectiveness (VE) against hospitalization in the test-negative HAIVEN study. Nasal-throat swabs were tested by RT-PCR for influenza and VE was determined based on odds of vaccination by generalized estimating equations. Vaccine-specific antibody was measured in a subset of enrollees. RESULTS: A total of 6,129 adults were enrolled from ten hospitals. Adjusted VE against A(H3N2) was 22.8% (95% C.I. 8.3%, 35.0%), pooled across both years and 49.4% (95% C.I. 34.3%, 61.1%) against B/Yamagata. In 2017-2018, the A(H3N2) VE point estimate for the cell-based vaccine was 43.0% (95% C.I. -36.3%, 76.1%; 56 vaccine recipients) compared to 24.0% (95% C.I. 3.9%, 39.9%) for egg based vaccines. Among 643 with serology data, hemagglutinin antibodies against the egg-based A(H3N2) vaccine strain were increased in influenza-negative individuals. CONCLUSIONS: Low VE for the A/Hong Kong/4801/2014 vaccine virus in both A(H3N2) seasons emphasizes concerns for continued changes in H3N2 antigenic epitopes, including changes that may impact glycosylation and ultimately reduce VE. |
Incorporating real-time influenza detection into the test-negative design for estimating influenza vaccine effectiveness: The real-time test-negative design (rtTND).
Feldstein LR , Self WH , Ferdinands JM , Randolph AG , Aboodi M , Baughman AH , Brown SM , Exline MC , Files DC , Gibbs K , Ginde AA , Gong MN , Grijalva CG , Halasa N , Khan A , Lindsell CJ , Newhams M , Peltan ID , Prekker ME , Rice TW , Shapiro NI , Steingrub J , Talbot HK , Halloran ME , Patel M . Clin Infect Dis 2020 72 (9) 1669-1675 With rapid and accurate molecular influenza testing now widely available in clinical settings, influenza vaccine effectiveness (VE) studies can prospectively select participants for enrollment based on real-time results rather than enrolling all eligible patients regardless of influenza status, as in the traditional test-negative design (TND). Thus, we explore advantages and disadvantages of modifying the TND for estimating VE by using real-time, clinically available viral testing results paired with acute respiratory infection eligibility criteria for identifying influenza cases and test-negative controls prior to enrollment. This modification, which we have called the real-time test-negative design (rtTND), has the potential to improve influenza VE studies by optimizing the case-to-test-negative control ratio, more accurately classifying influenza status, improving study efficiency, reducing study cost, and increasing study power to adequately estimate VE. Important considerations for limiting biases in the rtTND include the need for comprehensive clinical influenza testing at study sites and accurate influenza tests. |
Vaccine effectiveness against influenza-associated lower respiratory tract infections in hospitalized adults, Louisville, Kentucky, 2010-2013
Chow EJ , Rolfes MA , Carrico RL , Furmanek S , Ramirez JA , Ferdinands JM , Fry AM , Patel MM . Open Forum Infect Dis 2020 7 (7) ofaa262 BACKGROUND: Preventing severe complications of influenza such as hospitalization is a public health priority; however, estimates of influenza vaccine effectiveness (VE) against influenza-associated acute lower respiratory tract infection (LRTI) hospitalizations are limited. We examined influenza VE against influenza-associated LRTIs in hospitalized adult patients. METHODS: We retrospectively analyzed data from a randomized trial of oseltamivir treatment in adults hospitalized with LRTI in Louisville, Kentucky, from 2010 to 2013. Patients were systematically tested for influenza at the time of enrollment. We estimated VE as 1 - the adjusted odds ratio (aOR) of antecedent vaccination in influenza-positives vs negatives × 100%. Vaccination status was obtained by patient self-report. Using logistic regression adjusting for age, sex, season, timing of illness, history of chronic lung disease, and activities of daily living, we estimated VE against hospitalized influenza-associated LRTIs and community-acquired pneumonia (CAP) with radiographic findings of infiltrate. RESULTS: Of 810 patients with LRTI (median age, 62 years), 184 (23%) were influenza-positive and 57% had radiographically confirmed CAP. Among influenza-positives and -negatives, respectively, 61% and 69% were vaccinated. Overall, 29% were hospitalized in the prior 90 days and >80% had comorbidities. Influenza-negatives were more likely to have a history of chronic obstructive pulmonary disease than influenza-positives (59% vs 48%; P = .01), but baseline medical conditions were otherwise similar. Overall, VE was 35% (95% CI, 4% to 56%) against influenza-associated LRTI and 51% (95% CI, 13% to 72%) against influenza-associated radiographically confirmed CAP. CONCLUSIONS: Vaccination reduced the risk of hospitalization for influenza-associated LRTI and radiographically confirmed CAP. Clinicians should maintain high rates of influenza vaccination to prevent severe influenza-associated complications. |
Prospective cohort study of influenza vaccine effectiveness among healthcare personnel in Lima, Peru: Estudio Vacuna de Influenza Peru, 2016-2018
Wesley MG , Soto G , Arriola CS , Gonzales M , Newes-Adeyi G , Romero C , Veguilla V , Levine MZ , Silva M , Ferdinands JM , Dawood FS , Reynolds SB , Hirsch A , Katz M , Matos E , Ticona E , Castro J , Castillo M , Bravo E , Cheung A , Phadnis R , Martin ET , Tinoco Y , Neyra Quijandria JM , Azziz-Baumgartner E , Thompson MG . Influenza Other Respir Viruses 2020 14 (4) 391-402 BACKGROUND: The Estudio Vacuna de Influenza Peru (VIP) cohort aims to describe the frequency of influenza virus infection, identify predictors of vaccine acceptance, examine the effects of repeated influenza vaccination on immunogenicity, and evaluate influenza vaccine effectiveness among HCP. METHODS: The VIP cohort prospectively followed HCP in Lima, Peru, during the 2016-2018 influenza seasons; a fourth year is ongoing. Participants contribute blood samples before and after the influenza season and after influenza vaccination (for vaccinees). Weekly surveillance is conducted to identify acute respiratory or febrile illnesses (ARFI). When an ARFI is identified, participants self-collect nasal swabs that are tested for influenza viruses by real-time reverse transcriptase-polymerase chain reaction. Influenza vaccination status and 5-year vaccination history are ascertained. We analyzed recruitment and enrollment results for 2016-2018 and surveillance participation for 2016-2017. RESULTS: In the first 3 years of the cohort, VIP successfully contacted 92% of potential participants, enrolled 76% of eligible HCP, and retained >90% of participants across years. About half of participants are medical assistants (54%), and most provide "hands-on" medical care (76%). Sixty-nine percent and 52% of participants completed surveillance for >70% of weeks in years 1 and 2, respectively. Fewer weeks of completed surveillance was associated with older age (>/=50 years), being a medical assistant, self-rated health of fair or poor, and not receiving the influenza vaccine during the current season (P-values < .05). CONCLUSIONS: The VIP cohort provides an opportunity to address knowledge gaps about influenza virus infection, vaccination uptake, effectiveness and immunogenicity among HCP. |
Influenza vaccine effectiveness in inpatient and outpatient settings in the United States, 2015 - 2018
Tenforde MW , Chung J , Smith ER , Talbot HK , Trabue CH , Zimmerman RK , Silveira FP , Gaglani M , Murthy K , Monto AS , Martin ET , McLean HQ , Belongia EA , Jackson LA , Jackson ML , Ferdinands JM , Flannery B , Patel MM . Clin Infect Dis 2020 73 (3) 386-392 BACKGROUND: Demonstration of influenza vaccine effectiveness (VE) against hospitalization for severe illness in addition to milder outpatient illness may strengthen vaccination messaging and improve suboptimal uptake in the U.S. Our objective was to compare patient characteristics and VE between U.S. inpatient and outpatient VE networks. METHODS: We tested adults >/=18-years with acute respiratory illness (ARI) for influenza within two VE networks, one outpatient- and the other hospital-based, from 2015-2018. We compared age, sex, and chronic high-risk conditions between populations. The test-negative design was used to compare vaccination odds in influenza-positive cases versus influenza-negative controls. We estimated VE using logistic regression adjusting for site, age, sex, race/ethnicity, peak influenza activity, time-to-testing from symptom-onset, season (overall VE) and underlying conditions. VE differences (DeltaVE) were assessed with 95% confidence intervals (CI) determined through bootstrapping with significance defined as excluding the null. RESULTS: The VE networks enrolled 14,573 (4144 influenza-positive) outpatients and 6769 (1452 influenza-positive) inpatients. Inpatients were older (median 62-years vs. 49-years) and had more high-risk conditions (median 4 vs. 1). Overall influenza VE across seasons was 31% (95%CI:26%-37%) among outpatients and 36% (27%-44%) among inpatients. Strain-specific VE among outpatients versus inpatients was 37% (25%-47%) vs. 53% (37%-64%) against H1N1pdm09, 19% (9%-27%) vs. 23% (8%-35%) against H3N2, and 46% (38%-53%) vs. 46% (31%-58%) against B-viruses. DeltaVE was not significant for any comparison across all sites. CONCLUSIONS: Inpatients and outpatients with ARI represent distinct populations. Despite comparatively poor health status among inpatients, influenza vaccination was effective in preventing hospitalizations associated with influenza. |
Waning of measured influenza vaccine effectiveness over time: the potential contribution of leaky vaccine effect
Tokars JI , Patel MM , Foppa IM , Reed C , Fry AM , Ferdinands JM . Clin Infect Dis 2020 71 (10) e633-e641 INTRODUCTION: Several observational studies have shown decreases in measured influenza vaccine effectiveness (mVE) during influenza seasons. One study found decreases of 6%-11% per month during the 2011-12 to 2014-15 seasons. These findings could indicate waning immunity but could also occur if vaccine effectiveness is stable and vaccine provides partial protection in all vaccinees ("leaky") rather than complete protection in a subset of vaccinees. Since it is not known whether influenza vaccine is leaky, we simulated the 2011-12 to 2014-15 influenza seasons to estimate the potential contribution of leaky vaccine effect to the observed decline in mVE. METHODS: We used available data to estimate daily numbers of vaccinations and infections with A/H1N1, A/H3N2 and B viruses. We assumed that vaccine effect was leaky, calculated mVE as 1 minus the Mantel-Haenszel relative risk of vaccine on incident cases and determined the mean mVE change per 30 days since vaccination. Because change in mVE was highly dependent on infection rates, we performed simulations using low (15%) and high (31%) total (including symptomatic and asymptomatic) seasonal infection rates. RESULTS: For the low infection rate, decreases (absolute) in mVE per 30 days after vaccination were 2% for A/H1N1 and 1% for A/H3N2and B viruses. For high infection rate, decreases were 5% for A/H1N1, 4% for A/H3, and 3% for B viruses. CONCLUSIONS: The leaky vaccine bias could account for some, but probably not all of the observed intra-seasonal decreases in mVE. These results underscore the need for strategies to deal with intra-seasonal vaccine effectiveness decline. |
Relative and absolute effectiveness of high-dose and standard-dose influenza vaccine against influenza-related hospitalization among older adults - United States, 2015-2017
Doyle JD , Beacham L , Martin ET , Talbot HK , Monto A , Gaglani M , Middleton DB , Silveira FP , Zimmerman RK , Alyanak E , Smith ER , Flannery BL , Rolfes M , Ferdinands JM . Clin Infect Dis 2020 72 (6) 995-1003 BACKGROUND: Seasonal influenza causes substantial morbidity and mortality in older adults. High-dose inactivated influenza vaccine (HD-IIV), with increased antigen content compared to standard-dose influenza vaccines (SD-IIV), is licensed for use in people aged >/=65 years. We sought to evaluate the effectiveness of HD-IIV and SD-IIV for prevention of influenza-associated hospitalizations. METHODS: Hospitalized patients with acute respiratory illness were enrolled in an observational vaccine effectiveness study at eight hospitals in the United States Hospitalized Adult Influenza Vaccine Effectiveness Network during the 2015-2016 and 2016-2017 influenza seasons. Enrolled patients were tested for influenza, and receipt of influenza vaccine by type was recorded. Effectiveness of SD-IIV and HD-IIV was estimated using a test-negative design (comparing odds of influenza among vaccinated and unvaccinated patients). Relative effectiveness of SD-IIV and HD-IIV was estimated using logistic regression. RESULTS: Among 1487 enrolled patients aged >/=65 years, 1107 (74%) were vaccinated; 622 (56%) received HD-IIV and 485 (44%) received SD-IIV. Overall, 277 (19%) tested positive for influenza, including 98 (16%) who received HD-IIV, 87 (18%) who received SD-IIV, and 92 (24%) who were unvaccinated. After adjusting for confounding variables, effectiveness of SD-IIV was 6% (95% confidence interval [CI] -42%, 38%) and that of HD-IIV was 32% (95%CI -3%, 54%), for a relative effectiveness of HD-IIV versus SD-IIV of 27% (95%CI -1%, 48%). CONCLUSIONS: During two U.S. influenza seasons, vaccine effectiveness was low to moderate for prevention of influenza hospitalization among adults aged >/=65 years. High-dose vaccine offered greater effectiveness. None of these findings were statistically significant. |
Influenza vaccine effectiveness in the inpatient setting; evaluation of potential bias in the test negative design by use of alternate control groups
Segaloff HE , Cheng B , Miller AV , Petrie JG , Malosh RE , Cheng C , Lauring AS , Lamerato L , Ferdinands JM , Monto AS , Martin ET . Am J Epidemiol 2019 189 (3) 250-260 The test negative design is validated in outpatient but not inpatient studies of influenza vaccine effectiveness. The prevalence of chronic pulmonary disease among inpatients may lead to nonrepresentative controls. Test negative design estimates are biased if vaccine administration is associated with incidence of non-influenza viruses. We evaluated whether control group selection and effects of vaccination on non-influenza viruses biased vaccine effectiveness in our study. Subjects were enrolled at the University of Michigan and Henry Ford hospitals during the 2014-15 and 2015-16 seasons. Patients presenting with acute respiratory infection were enrolled and tested for respiratory viruses. Vaccine effectiveness was estimated using three control groups: influenza negative, other respiratory virus positive, and pan-negative individuals; it was also estimated for other common respiratory viruses. In 2014-15, vaccine effectiveness was 41.1% (95% CI: 1.7%, 64.7%) using influenza negative, 24.5% (95% CI: -42.6%, 60.1%) using other-virus positive, and 45.8% (95% CI: 5.7%, 68.9%) using pan-negative controls. In 2015-16, vaccine effectiveness was 68.7% (95% CI: 44.6%, 82.5%) using influenza negative, 63.1% (95% CI: 25.0%, 82.2%) using other-virus positive, and 71.1% (46.2%, 84.8%) using pan-negative controls. Vaccination did not alter odds of other respiratory viruses. Results support use of the test negative design among inpatients. |
Waning of influenza vaccine protection: Exploring the trade-offs of changes in vaccination timing among older adults
Ferdinands JM , Alyanak E , Reed C , Fry AM . Clin Infect Dis 2019 70 (8) 1550-1559 BACKGROUND: Recent studies of influenza vaccine effectiveness (VE) observed lower effectiveness with increasing time since vaccination, raising the question of optimal vaccination timing. We sought to evaluate the estimated number of influenza-associated hospitalizations among older adults due to potential changes in vaccination timing. METHODS: Using empirical data and a health state transition model, we estimated change in influenza-associated hospitalizations predicted to occur among the U.S. population aged >/=65 years if vaccination were delayed until October 1. We assumed the vaccination timing, coverage, and effectiveness observed in 2012-13 as a prototypical influenza season, ~7% monthly waning of VE, and that between 0% and 50% of individuals who usually get vaccinated earlier than October failed to get vaccinated. We also assessed change in influenza-associated hospitalizations if vaccination uptake shifted substantially toward August and September. RESULTS: In a typical season, delaying vaccination until October increased influenza hospitalizations if more than 14% of older adults usually vaccinated in August and September failed to get vaccinated. The consequences of delayed vaccination depended heavily on influenza season timing, rate of waning, and overall VE. A shift toward vaccination in August and September led to, on average, an increase in influenza-associated hospitalizations, but this result was also sensitive to influenza season timing. CONCLUSIONS: Consequences of delayed vaccination varied widely. Uncertainties about vaccine waning and effects of a delay on vaccine coverage suggest it is premature to change current vaccine recommendations, although it may be prudent to prevent a substantial shift toward early vaccination. |
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