BACKGROUND: Previous investigations into clinical signs and symptoms associated with influenza types and subtypes have not definitively established differences in the clinical presentation or severity of influenza disease. METHODS: The study population included children 0 through 17 years old enrolled at 8 New Vaccine Surveillance Network sites between 2015 and 2020 who tested positive for influenza virus by molecular testing. Demographic and clinical data were collected for study participants via parent/guardian interview and medical chart review. Descriptive statistics were used to summarize demographic and clinical characteristics by influenza subtype. Multivariable logistic regression and Cox proportional hazard models were used to assess effects of age, sex, influenza subtype, and history of asthma on severity, including hospital admission, need for supplemental oxygen, and length of stay. RESULTS: Retractions, cyanosis, and need for supplemental oxygen were more frequently observed among patients with influenza A(H1N1)pdm09. Headaches and sore throat were more commonly reported among patients with influenza B. Children with influenza A(H1N1)pdm09 and children with asthma had significantly increased odds of hospital admission (adjusted odds ratio (AOR): 1.39, 95% CI: 1.14-1.69 and AOR: 2.14, 95% CI: 1.72-2.67, respectively). During admission, children with influenza A(H1N1)pdm09 had significantly increased use of supplemental oxygen compared to children with A(H3N2) (AOR: 0.60, 95% CI: 0.44-0.82) or B (AOR: 0.56, 95% CI: 0.41-0.76). CONCLUSIONS: Among children presenting to the emergency department and admitted to the hospital, influenza A(H1N1)pdm09 caused more severe disease compared to influenza A(H3N2) and influenza B. Asthma also contributed to severe influenza disease regardless of subtype.

BACKGROUND: The coronavirus disease 2019 pandemic disrupted respiratory syncytial virus (RSV) seasonality resulting in early, atypical RSV seasons in 2021 and 2022, with an intense 2022 peak overwhelming many pediatric healthcare facilities. METHODS: We conducted prospective surveillance for acute respiratory illness during 2016-2022 at 7 pediatric hospitals. We interviewed parents, reviewed medical records, and tested respiratory specimens for RSV and other respiratory viruses. We estimated annual RSV-associated hospitalization rates in children aged <5 years and compared hospitalization rates and characteristics of RSV-positive hospitalized children over 4 prepandemic seasons (2016-2020) to those hospitalized in 2021 or 2022. RESULTS: There was no difference in median age or age distribution between prepandemic and 2021 seasons. Median age of children hospitalized with RSV was higher in 2022 (9.6 months vs 6.0 months, P < .001). RSV-associated hospitalization rates were higher in 2021 and 2022 than the prepandemic average across age groups. Comparing 2021 to 2022, RSV-associated hospitalization rates were similar among children <2 years of age; however, children aged 24 to 59 months had significantly higher rates of RSV-associated hospitalization in 2022 (rate ratio 1.68 [95% confidence interval 1.37-2.00]). More RSV-positive hospitalized children received supplemental oxygen and there were more respiratory virus codetections in 2022 than in prepandemic seasons (P < .001 and P = .003, respectively), but there was no difference in the proportion hypoxemic, mechanically ventilated, or admitted to intensive care. CONCLUSIONS: The atypical 2021 and 2022 RSV seasons resulted in higher hospitalization rates with similar disease severity to prepandemic seasons.

OBJECTIVE: To assess medical costs of hospitalizations and emergency department (ED) care associated with respiratory syncytial virus (RSV) disease in children enrolled in the New Vaccine Surveillance Network. STUDY DESIGN: We used accounting and prospective surveillance data from six pediatric health systems to assess direct medical costs from laboratory-confirmed RSV-associated hospitalizations (n=2,007) and ED visits (n=1,267) from 2016 through 2019 among children aged <5 years. We grouped costs into categories relevant to clinical care and administrative billing practices. We examined RSV-associated medical costs by care setting using descriptive and bivariate analyses. We assessed associations between known RSV risk factors and hospitalization costs and length of stay (LOS) using chi-square tests of association. RESULTS: The median cost was $7,100 (IQR: $4,006-$13,355) per hospitalized child and $503 (IQR: $387-$930) per ED visit. Eighty percent (n=2,628) of our final sample were children aged <2 years. Fewer weeks' gestational age (GA) was associated with higher median costs in hospitalized children [p<0.001, ≥37 weeks' GA: $6,840 ($3,905-$12,450); 29-36 weeks' GA: $7,721 ($4,362-$15,274); <29 w weeks' GA: $9,131 ($4,518-$19,924)]. Full-term infants accounted for 70% of the total expenditures in our sample. Almost three quarters of the healthcare dollars spent originated in children under 12 months of age; the primary age group targeted by recommended RSV prophylactics. CONCLUSIONS: Reducing the cost burden for RSV-associated medical care in young children will require prevention of RSV in all young children, not just high-risk infants. Newly available maternal vaccine and immunoprophylaxis products could substantially reduce RSV-associated medical costs.

Respiratory syncytial virus (RSV) is the leading cause of hospitalization among infants in the United States. In August 2023, CDC's Advisory Committee on Immunization Practices recommended nirsevimab, a long-acting monoclonal antibody, for infants aged <8 months to protect against RSV-associated lower respiratory tract infection during their first RSV season and for children aged 8-19 months at increased risk for severe RSV disease. In phase 3 clinical trials, nirsevimab efficacy against RSV-associated lower respiratory tract infection with hospitalization was 81% (95% CI = 62%-90%) through 150 days after receipt; post-introduction effectiveness has not been assessed in the United States. In this analysis, the New Vaccine Surveillance Network evaluated nirsevimab effectiveness against RSV-associated hospitalization among infants in their first RSV season during October 1, 2023-February 29, 2024. Among 699 infants hospitalized with acute respiratory illness, 59 (8%) received nirsevimab ≥7 days before symptom onset. Nirsevimab effectiveness was 90% (95% CI = 75%-96%) against RSV-associated hospitalization with a median time from receipt to symptom onset of 45 days (IQR = 19-76 days). The number of infants who received nirsevimab was too low to stratify by duration from receipt; however, nirsevimab effectiveness is expected to decrease with increasing time after receipt because of antibody decay. Although nirsevimab uptake and the interval from receipt of nirsevimab were limited in this analysis, this early estimate supports the current nirsevimab recommendation for the prevention of severe RSV disease in infants. Infants should be protected by maternal RSV vaccination or infant receipt of nirsevimab.

In the United States, annual influenza vaccination is recommended for all persons aged ≥6 months. Using data from four vaccine effectiveness (VE) networks during the 2023-24 influenza season, interim influenza VE was estimated among patients aged ≥6 months with acute respiratory illness-associated medical encounters using a test-negative case-control study design. Among children and adolescents aged 6 months-17 years, VE against influenza-associated outpatient visits ranged from 59% to 67% and against influenza-associated hospitalization ranged from 52% to 61%. Among adults aged ≥18 years, VE against influenza-associated outpatient visits ranged from 33% to 49% and against hospitalization from 41% to 44%. VE against influenza A ranged from 46% to 59% for children and adolescents and from 27% to 46% for adults across settings. VE against influenza B ranged from 64% to 89% for pediatric patients in outpatient settings and from 60% to 78% for all adults across settings. These findings demonstrate that the 2023-24 seasonal influenza vaccine is effective at reducing the risk for medically attended influenza virus infection. CDC recommends that all persons aged ≥6 months who have not yet been vaccinated this season get vaccinated while influenza circulates locally.

AIMS: Swine are a mixing vessel for the emergence of novel reassortant influenza A viruses (IAV). Interspecies transmission of swine-origin IAV poses a public health and pandemic risk. In the United States, the majority of zoonotic IAV transmission events have occurred in association with swine exposure at agricultural fairs. Accordingly, this human-animal interface necessitates mitigation strategies informed by understanding of interspecies transmission mechanisms in exhibition swine. Likewise, the diversity of IAV in swine can be a source for novel reassortant or mutated viruses that pose a risk to both swine and human health. METHODS AND RESULTS: In an effort to better understand those risks, here we investigated the epidemiology of IAV in exhibition swine and subsequent transmission to humans by performing phylogenetic analyses using full genome sequences from 272 IAV isolates collected from exhibition swine and 23 A(H3N2)v viruses from human hosts during 2013-2015. Sixty-seven fairs (24.2%) had at least one pig test positive for IAV with an overall estimated prevalence of 8.9% (95% CI: 8.3-9.6, Clopper-Pearson). Of the 19 genotypes found in swine, 5 were also identified in humans. There was a positive correlation between the number of human cases of a genotype and its prevalence in exhibition swine. Additionally, we demonstrated that A(H3N2)v viruses clustered tightly with exhibition swine viruses that were prevalent in the same year. CONCLUSIONS: These data indicate that multiple genotypes of swine-lineage IAV have infected humans, and highly prevalent IAV genotypes in exhibition swine during a given year are also the strains detected most frequently in human cases of variant IAV. Continued surveillance and rapid characterization of IAVs in exhibition swine can facilitate timely phenotypic evaluation and matching of candidate vaccine strains to those viruses present at the human-animal interface which are most likely to spillover into humans.

SARS-CoV-2 infection in young children is often mild or asymptomatic; however, some children are at risk for severe disease. Data describing the protective effectiveness of COVID-19 mRNA vaccines against COVID-19-associated emergency department (ED) visits and hospitalization in this population are limited. Data from the New Vaccine Surveillance Network, a prospective population-based surveillance system, were used to estimate vaccine effectiveness using a test-negative, case-control design and describe the epidemiology of SARS-CoV-2 in infants and children aged 6 months-4 years during July 1, 2022-September 30, 2023. Among 7,434 children included, 5% received a positive SARS-CoV-2 test result, and 95% received a negative test result; 86% were unvaccinated, 4% had received 1 dose of any vaccine product, and 10% had received ≥2 doses. When compared with receipt of no vaccines among children, receipt of ≥2 COVID-19 mRNA vaccine doses was 40% effective (95% CI = 8%-60%) in preventing ED visits and hospitalization. These findings support existing recommendations for COVID-19 vaccination of young children to reduce COVID-19-associated ED visits and hospitalization.

The National Center for Health Statistics (NCHS) disseminates information on a broad range of health topics through diverse publications. These publications must rely on clear and transparent presentation standards that can be broadly and efficiently applied. Standards are particularly important for large, cross-cutting reports where estimates cannot be individually evaluated and indicators of precision cannot be included alongside the estimates. This report describes the NCHS Data Presentation Standards for Proportions. The multistep NCHS Data Presentation Standards for Proportions are based on a minimum denominator sample size and on the absolute and relative widths of a confidence interval calculated using the Clopper-Pearson method. Proportions (usually multiplied by 100 and expressed as percentages) are the most commonly reported estimates in NCHS reports.

The New Vaccine Surveillance Network (NVSN) is a prospective, active, population-based surveillance platform that enrolls children with acute respiratory illnesses (ARIs) at seven pediatric medical centers. ARIs are caused by respiratory viruses including influenza virus, respiratory syncytial virus (RSV), human metapneumovirus (HMPV), human parainfluenza viruses (HPIVs), and most recently SARS-CoV-2 (the virus that causes COVID-19), which result in morbidity among infants and young children (1-6). NVSN estimates the incidence of pathogen-specific pediatric ARIs and collects clinical data (e.g., underlying medical conditions and vaccination status) to assess risk factors for severe disease and calculate influenza and COVID-19 vaccine effectiveness. Current NVSN inpatient (i.e., hospital) surveillance began in 2015, expanded to emergency departments (EDs) in 2016, and to outpatient clinics in 2018. This report describes demographic characteristics of enrolled children who received care in these settings, and yearly circulation of influenza, RSV, HMPV, HPIV1-3, adenovirus, human rhinovirus and enterovirus (RV/EV),* and SARS-CoV-2 during December 2016-August 2021. Among 90,085 eligible infants, children, and adolescents (children) aged <18 years(†) with ARI, 51,441 (57%) were enrolled, nearly 75% of whom were aged <5 years; 43% were hospitalized. Infants aged <1 year accounted for the largest proportion (38%) of those hospitalized. The most common pathogens detected were RV/EV and RSV. Before the emergence of SARS-CoV-2, detected respiratory viruses followed previously described seasonal trends, with annual peaks of influenza and RSV in late fall and winter (7,8). After the emergence of SARS-CoV-2 and implementation of associated pandemic nonpharmaceutical interventions and community mitigation measures, many respiratory viruses circulated at lower-than-expected levels during April 2020-May 2021. Beginning in summer 2021, NVSN detected higher than anticipated enrollment of hospitalized children as well as atypical interseasonal circulation of RSV. Further analyses of NVSN data and continued surveillance are vital in highlighting risk factors for severe disease and health disparities, measuring the effectiveness of vaccines and monoclonal antibody-based prophylactics, and guiding policies to protect young children from pathogens such as SARS-CoV-2, influenza, and RSV.

Diagnostic assays that can simultaneously determine the presence of infection with multiple pathogens are key for diagnosis and surveillance. Current multiplex diagnostic assays are complex and often have limited availability. We developed a simple, multianalyte, pathogen detection assay for screening and serosurveillance using the Luminex Magpix platform that is high throughput and can be helpful in monitoring multiple diseases. The Luminex bead-based 10-plex immunoassay for the detection of HIV-1, HIV-2, Treponema pallidum, hepatitis B virus (HBV), hepatitis C virus (HCV), herpes simplex virus 1 (HSV-1), and HSV-2 infections was accomplished by coupling beads with specific antigens to detect IgG antibodies in plasma or serum samples. Each coupled antigen was systematically optimized, and the performance was evaluated using a panel of well-characterized specimens (n=417) that contained antibodies to HIV-1, HIV-2, T. pallidum, HBV, HCV, HSV-1, and HSV-2. The multiplex assay had a sensitivity of 92.2% (95% Clopper-Pearson confidence interval [CI], 90.2 to 94.0%) and a specificity of 98.1% (95% CI, 97.6 to 98.7%). The sensitivities and specificities for disease-specific biomarker detection ranged from 68.7 to 100% and 95.6 to 100%, respectively. The results showed that the 10-plex immunoassay had an overall agreement of 96.7% (95% CI, 96.7 to 97.3%) with reference tests and a corresponding kappa value of 0.91 (95% CI, 0.90 to 0.93). Kappa values for the individual pathogens ranged from 0.69 to 1.00. The assay is robust and allows the simultaneous detection of antibodies to multiple antigens using a small sample volume in a high-throughput format. This assay has the potential to simplify disease surveillance by providing an alternative to expensive and highly specialized individual tests.

Environmental health practitioners play a critical role in the prevention, identification, and mitigation of Legionnaires' disease outbreaks. Over the last 20 years, Legionnaires' disease outbreaks have increased significantly and the Centers for Disease Control and Prevention (CDC) continues to learn about the disease and how to prevent it. For example, CDC investigations show almost all (9 in 10) Legionnaires' disease outbreaks were caused by problems preventable with more effective building water management. Water management programs have become an important industry standard and are now required in healthcare facilities nationwide. | | This month's column highlights updated and new resources for preventing Legionnaires' disease for environmental health practitioners. These tools include updated guidance on preventing Legionella in water systems and devices, a new toolkit for controlling Legionella in common sources of exposure, and an updated Legionella Environmental Health Assessment Form for building water systems.

We piloted a methodology for collecting and interpreting root cause-or environmental deficiency (ED)-information from Legionnaires' disease (LD) outbreak investigation reports. The methodology included a classification framework to assess common failures observed in the implementation of water management programs (WMPs). We reviewed reports from fourteen CDC-led investigations between 1 January 2015 and 21 June 2019 to identify EDs associated with outbreaks of LD. We developed an abstraction guide to standardize data collection from outbreak reports and define relevant parameters. We categorized each ED according to three criteria: ED type, WMP-deficiency type, and source of deficiency. We calculated the prevalence of EDs among facilities and explored differences between facilities with and without WMPs. A majority of EDs identified (81%) were classified as process failures. Facilities with WMPs (n = 8) had lower prevalence of EDs attributed to plumbed devices (9.1%) and infrastructure design (0%) than facilities without WMPs (n = 6; 33.3% and 24.2%, respectively). About three quarters (72%) of LD cases and 81% of the fatalities in our sample originated at facilities without a WMP. This report highlights the importance of WMPs in preventing and mitigating outbreaks of LD. Building water system process management is a primary obstacle toward limiting the root causes of LD outbreaks. Greater emphasis on the documentation, verification, validation, and continuous program review steps will be important in maximizing the effectiveness of WMPs.

OBJECTIVE: Lay the groundwork for future survey validation and harmonization efforts by comparing prevalence rates of self-reported visual impairment (VI) and blindness measured across federally-funded national surveys by age-groups and to prevalence rates of presenting impairment and blindness measured by physical examination. DESIGN: Cross-sectional comparison of national surveys. PARTICIPANTS: Participants in: 2016 American Community Survey, the 2016 Behavioral Risk Factor Surveillance System, the 2016 National Health Interview Survey, the 1999-2008 National Health and Nutrition Examination Survey (NHANES), and the 2016 National Survey of Children's Health. METHODS: We estimated VI and blindness prevalence rates and confidence intervals for each survey measure and age-group using the Clopper-Pearson method. We then estimated weighted self-reported VI and blindness prevalence rates across survey measures by age-group using inverse variance weighting, fitted trend lines to age-group estimates, and used the trend-line equations to estimate the number of U.S. persons with VI and blindness in 2016. We compared these self-report estimates to those generated from NHANES physical evaluations of presenting VI and blindness. MAIN OUTCOME MEASURES: The variability of prevalence estimates of VI and blindness RESULTS: Survey response estimates of blindness varied between 0.1% and 5.6% for age-groups <65 years and between 0.6% to 16.6% for ages >=65. Estimates of VI varied between 1.6% and 24.8% for age-groups <65 years and between 2.2% and 26.6% for age-groups >=65. For summarized survey results and NHANES physical evaluation, prevalence rates for VI increased significantly with age-group. Blindness prevalence increased significantly with age-group for summarized survey responses but not for NHANES physical examination. Based on extrapolations of NHANES physical examination data to all ages, we estimated that in 2016, 23.4 million persons in the U.S. (7.2%) had VI or blindness, an evaluated visual acuity of 20/40 or worse in the better-seeing eye before correction; based on weighted self-reported surveys, we estimated 24.8 million persons (7.7%) had presenting VI or blindness. CONCLUSIONS: Prevalence rates of VI and blindness obtained from national survey measures varied widely across surveys and age-groups. Additional research is needed to validate the ability of survey self-report measures of VI and blindness to replicate results obtained through clinical exam by an eye health professional.