INTRODUCTION: This research aims to characterize disparities in mpox- and vaccine-related knowledge in gay, bisexual, and other men who have sex with men in the U.S. METHODS: The authors conducted a study using the American Men's Internet Survey, which includes 823 cisgender (defined as their gender identity matching their sex assigned at birth) males aged ≥15 years from August 5 to 15, 2022. The authors evaluated sociodemographic and behavioral factors associated with mpox knowledge, including race/ethnicity, region, age group, and HIV pre-exposure prophylaxis use using chi-square tests. RESULTS: The authors identified knowledge gaps, with many participants unsure about whether individuals need 2 doses of the vaccine (34.4%) and whether the vaccine confers immediate protection (27.2%). The authors observed racial and regional disparities (p<0.01), with 24.4% of non-Hispanic Black men and 18.1% of men living in the South reporting little to no mpox awareness. Among the 707 self-reported HIV-negative participants, people who used pre-exposure prophylaxis within the past year were more likely to exhibit high awareness about mpox than people who did not use pre-exposure prophylaxis. CONCLUSIONS: Findings suggest the potential to leverage existing networks (i.e., sexually transmitted infection or general health care services with pre-exposure prophylaxis use) for future targeted health service programming or education campaigns for mpox vaccination among gay, bisexual, and other men who have sex with men.

BACKGROUND: Outer membrane vesicle (OMV) meningococcal serogroup B (MenB) vaccines might be protective against gonorrhea. We evaluated the effectiveness of MenB-4C, an OMV MenB vaccine, against gonorrhea. METHODS: We identified gonococcal mono-infections, chlamydial mono-infections, and gonococcal/chlamydial co-infections among persons aged 15-30 years in the electronic health records of Kaiser Permanente Northern California during 2016-2021. We determined MenB-4C vaccination status (vaccinated [≥1 MenB-4C vaccine dose] or unvaccinated [MenB-4C vaccine naïve]) at each infection. We used log-binomial regression with generalized estimating equations to calculate adjusted prevalence ratios (APR) and 95 % confidence intervals (CI) to determine if MenB-4C vaccination was protective against gonococcal mono-infections compared to chlamydial mono-infection. We also evaluated if MenB-4C vaccination was protective against gonococcal/chlamydial co-infections. Because of concerns with small sample size of vaccinated persons, we estimated effects using a limited model (adjusting for race/ethnicity only) and an expanded model (adjusting for additional potential confounders). RESULTS: Of 68,454 persons, we identified 558 (0.8 %) MenB-4C vaccinated persons and 85,393 infections (13,000 gonococcal mono-infections, 68,008 chlamydial mono-infections, and 4385 gonococcal/chlamydial co-infections). After adjusting for race/ethnicity, MenB-4C vaccination was 23 % protective against gonococcal mono-infection compared to chlamydial mono-infection (APR = 0.77, 95 % CI = 0.64-0.99) in the limited model but not in the expanded model. CONCLUSION: MenB-4C vaccination was protective against gonococcal mono-infection, independent of race/ethnicity. This protective effect was not observed when other potential confounders were included in the analysis. Protection against gonococcal/chlamydial co-infection was not observed. Efficacy data from clinical trials are needed.

INTRODUCTION: There is no licensed vaccine against gonorrhea but Neisseria meningitidis serogroup B outer membrane vesicle-based vaccines, like MenB-4C, may offer cross-protection against gonorrhea. This systematic review and meta-analysis synthesized the published literature on MenB-4C vaccine effectiveness against gonorrhea. METHODS: We conducted a literature search of electronic databases (PubMed, Medline, Embase, Global Health, Scopus, Google Scholar, CINAHL, and Cochrane Library) to identify peer-reviewed papers, published in English, from 1/1/2013-7/12/2024 that reported MenB-4C vaccine effectiveness estimates against gonorrhea and gonorrhea/chlamydia co-infection, and the duration of MenB-4C vaccine-induced protection. We estimated pooled MenB-4C vaccine effectiveness (≥1 dose) against gonorrhea using the DerSimonian-Laird random effects model. RESULTS: Eight papers met our eligibility criteria. Receipt of ≥1 dose of MenB-4C vaccine was 23%-47% effective against gonorrhea. Two doses of MenB-4C vaccine were 33-40% effective against gonorrhea and one dose of MenB-4C vaccine was 26% effective. MenB-4C vaccine effectiveness against gonorrhea/chlamydia co-infection was mixed with two studies reporting effectiveness estimates of 32% and 44%, and two other studies showing no protective effect. MenB-4C vaccine effectiveness against gonorrhea was comparable in people living with HIV (44%) and people not living with HIV (23%-47%). Pooled MenB-4C vaccine effectiveness (≥1 dose) against gonorrhea was 32.4%. One study concluded that MenB-4C vaccine effectiveness against gonorrhea may wane approximately 36 months post-vaccination. CONCLUSION: MenB-4C vaccine is moderately effective against gonorrhea in various populations. Prospective clinical trials that assess the efficacy of MenB-4C against gonorrhea, gonorrhea/chlamydia co-infection, and duration of protection are warranted to strengthen this evidence.

We identified U.S. reports of postmenopausal bleeding in the VAERS (Vaccine Adverse Event Reporting System) between December 13, 2020, and December 13, 2021. Among 711,224 VAERS reports after coronavirus disease 2019 (COVID-19) vaccination, during our study period, we identified 554 presumptive postmenopausal bleeding reports; 434 were further classified as verified based on data abstracted from reports and medical records, when available. In the United States, by December 14, 2021, 58.8 million women aged 50 years or older had received at least one dose of a COVID-19 vaccine, corresponding to approximately seven verified VAERS postmenopausal bleeding reports per 1 million women aged 50 years or older who received a COVID-19 vaccine. Reports of postmenopausal bleeding after COVID-19 vaccination in VAERS were rare, and causes of postmenopausal bleeding based on medical record review were consistent with known causes of postmenopausal bleeding.

Neisseria gonorrhoeae infection (gonorrhoea) is a global public health challenge, causing substantial sexual and reproductive health consequences, such as infertility, pregnancy complications and increased acquisition or transmission of HIV. There is an urgency to controlling gonorrhoea because of increasing antimicrobial resistance to ceftriaxone, the last remaining treatment option, and the potential for gonorrhoea to become untreatable. No licensed gonococcal vaccine is available. Mounting observational evidence suggests that N. meningitidis serogroup B outer membrane vesicle-based vaccines may induce cross-protection against N. gonorrhoeae (estimated 30%-40% effectiveness using the 4CMenB vaccine). Clinical trials to determine the efficacy of the 4CMenB vaccine against N. gonorrhoeae are underway, as are Phase 1/2 studies of a new gonococcal-specific vaccine candidate. Ultimately, a gonococcal vaccine must be accessible, affordable and equitably dispensed, given that those most affected by gonorrhoea are also those who may be most disadvantaged in our societies, and most cases are in less-resourced settings. This vaccine value profile (VVP) provides a high level, holistic assessment of the current data to inform the potential public health, economic and societal value of pipeline vaccines. This was developed by a working group of subject matter experts from academia, non-profit organizations, public private partnerships and multi-lateral organizations. All contributors have extensive expertise on various elements of the N. gonorrhoeae VVP and collectively aimed to identify current research and knowledge gaps. The VVP was developed using published data obtained from peer-reviewed journals or reports.

Background In December 2020, two mRNA-based COVID-19 vaccines were authorized for use in the United States. Vaccine safety was monitored using the Vaccine Adverse Event Reporting System (VAERS), a passive surveillance system, and v-safe, an active surveillance system.Methods VAERS and v-safe data during December 14, 2020—June 14, 2021 were analyzed. VAERS reports were categorized as non-serious, serious, or death; reporting rates were calculated. Rates of reported deaths were compared to expected mortality rates by age. Proportions of v-safe participants reporting local and systemic reactions or health impacts the week following doses 1 and 2 were determined.Findings During the analytic period, 298,792,852 doses of mRNA vaccines were administered in the United States. VAERS processed 340,522 reports; 92·1% were non-serious; 6·6%, serious, non-death; and 1·3%, death. Over half of 7,914,583 v-safe participants self-reported local and systemic reactogenicity, more frequently after dose 2. Injection-site pain, fatigue, and headache were commonly reported during days 0–7 following vaccination. Reactogenicity was reported most frequently one day after vaccination; most reactions were mild. More reports of being unable to work or do normal activities occurred after dose 2 (32·1%) than dose 1 (11·9%); &lt;1% of participants reported seeking medical care after vaccination. Rates of deaths reported to VAERS were lower than expected background rates by age group.Interpretation Safety data from &gt;298 million doses of mRNA COVID-19 vaccine administered in the first 6 months of the U.S. vaccination program show the majority of reported adverse events were mild and short in duration.Competing Interest StatementDisclosures: Ruiling Liu- Stock or stock options, Johnson &amp;Johnson50 shares of stocks Moderna20 shares of stocks &amp; Spouse works for Ethicon|Johnson &amp; Johnson, on surgery robotics Funding StatementThis study did not receive any funding.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:Both VAERS and v-safe conduct surveillance as a public health function and are exempt from institutional review board review. This analysis was reviewed by the CDC and conducted in accordance with applicable federal law and CDC policy (See: 45 C.F.R. part 46.102(l)(2), 21 C.F.R. part 56; 42 U.S.C. 241(d); 5 U.S.C. 552a; 44 U.S.C. 3501 et seq.). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.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 produced in the present study are available upon reasonable request to the authors

Background Knowledge of expected rates of potential adverse events of special interest (AESI) that may occur coincidentally following COVID-19 vaccination is essential for vaccine safety surveillance and assessment. We calculated the expected rates of 21 potential AESI following COVID-19 vaccination among vaccinated persons within 1 day, 7 days, and 42 days of vaccination.Methods We used meta-analytic methods to estimate background rates of 21 medical conditions considered potential AESI and calculated expected rates of each potential AESI within 1 day, 7 days, and 42 days of vaccination.Results Background rates of three commonly monitored AESI, Guillain-Barre syndrome (GBS), myopericarditis, and all-cause deaths were 2.0 GBS cases/100,000 person-years, 1.3 myopericarditis cases/100,000 person-years, and 863.8 all-cause deaths/100,000 person-years, respectively. Based on these background rates, if 10,000,000 persons are vaccinated, we would expect 0.5, 3.7, and 22.5 GBS cases; 0.3, 2.4, and 14.3 myopericarditis cases; and 236.5, 1655.5, and 9932.8 all-cause deaths to occur in coincident temporal association (i.e., as a result of background incidence) within 1 day, 7 days, and 42 days of vaccination, respectively.Conclusion Knowledge of expected rates of potential AESI can help contextualize adverse health events associated temporally with immunization, aid in safety signal detection, guide COVID-19 vaccine public health communication, and inform benefit-risk assessments of COVID-19 vaccines.Competing Interest StatementThe authors have declared no competing interest.Funding StatementThere are no funding sources for this study.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:This analysis was exempt from CDC Institutional Review Board review.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.YesWe conducted a meta-analysis using incidence rate data from eligible published studies cited in this paper.

BACKGROUND: On 2/27/2021, FDA authorized Janssen COVID-19 Vaccine (Ad.26.COV2.S) for use in individuals 18 years of age and older. Vaccine safety was monitored using the Vaccine Adverse Event Reporting System (VAERS), a national passive surveillance system, and v-safe, a smartphone-based surveillance system. METHODS: VAERS and v-safe data from 2/27/2021 to 2/28/2022 were analyzed. Descriptive analyses included sex, age, race/ethnicity, seriousness, AEs of special interest (AESIs), and cause of death. For prespecified AESIs, reporting rates were calculated using the total number of doses of Ad26.COV2.S administered. For myopericarditis, observed-to-expected (O/E) analysis was performed based on the number verified cases, vaccine administration data, and published background rates. Proportions of v-safe participants reporting local and systemic reactions, as well as health impacts, were calculated. RESULTS: During the analytic period, 17,018,042 doses of Ad26.COV2.S were administered in the United States, and VAERS received 67,995 reports of AEs after Ad26.COV2.S vaccination. Most AEs (59,750; 87.9 %) were non-serious and were similar to those observed during clinical trials. Serious AEs included COVID-19 disease, coagulopathy (including thrombosis with thrombocytopenia syndrome; TTS), myocardial infarction, Bell's Palsy, and Guillain-Barré syndrome (GBS). Among AESIs, reporting rates per million doses of Ad26.COV2.S administered ranged from 0.06 for multisystem inflammatory syndrome in children to 263.43 for COVID-19 disease. O/E analysis revealed elevated reporting rate ratios (RRs) for myopericarditis; among adults ages 18-64 years, the RR was 3.19 (95 % CI 2.00, 4.83) within 7 days and 1.79 (95 % CI 1.26, 2.46) within 21 days of vaccination. Of 416,384 Ad26.COV2.S recipients enrolled into v-safe, 60.9 % reported local symptoms (e.g. injection site pain) and 75.9 % reported systemic symptoms (e.g., fatigue, headache). One-third of participants (141,334; 33.9 %) reported a health impact, but only 1.4 % sought medical care. CONCLUSION: Our review confirmed previously established safety risks for TTS and GBS and identified a potential safety concern for myocarditis.

Mpox vaccination is recommended for persons exposed to or at risk for mpox. About 25% of an online sample of MSM with presumed mpox exposure were vaccinated (≥1 dose). Vaccination was higher among younger MSM and MSM concerned about mpox or reporting sexual risk behaviors. Incorporating mpox vaccination into routine sexual health care and increasing 2-dose vaccination uptake is essential to preventing mpox acquisition, improving MSM sexual health, and averting future mpox outbreaks.

Background: Chemsex is the intentional use of drugs to enhance sexual activity. Chemsex drug use among men who have sex with men (MSM) is associated with sexual behaviors that increase sexually transmitted infection (STI) risks and adverse mental health outcomes. However, published data are largely based on MSM recruited from STI clinics. There are limited data about use of chemsex drugs among national samples of MSM in the United States. Using data from the American Men's Internet Survey (AMIS), we assessed the prevalence and correlates of use of chemsex drugs among sexually active MSM in the United States. Methods: We used data from the 2017 to 2020 AMIS cycles to examine the prevalence of chemsex drug use in the past 12 months among MSM. We calculated prevalence ratios (PR) and 95% confidence intervals (CI) to compare chemsex drug use across demographic, behavioral, and mental health factors. Results: Of 30,294 MSM, 3,113 (10.3%) reported chemsex drug use in the past 12 months. Of the 3,113 MSM who reported chemsex drug use, 65.1% reported ecstasy use, 42.5% reported crystal methamphetamine use, and 21.7% reported GHB use. Factors associated with chemsex drug use included condomless anal sex (PR = 1.93, 95%=1.69-2.20), problem drinking (PR = 2.36, 95% = 2.13-2.61), bacterial STI test (1.84, 95% CI = 1.68-2.02) and probable serious mental illness (PR = 1.92, 95% = 1.76-2.09). Conclusion: Chemsex drug use is associated with behaviors that increase STI risk and mental distress among MSM. Health programs that serve MSM can consider screening for chemsex drug use and offering sexual and mental health promotion and risk reduction interventions when necessary.

Observational studies demonstrated 30-40% effectiveness of OMV meningococcal serogroup-B vaccines against gonorrhea. To explore whether healthy vaccinee bias influenced such findings, we examined effectiveness of MenB-FHbp, a non-OMV vaccine that is not protective against gonorrhea. MenB-FHbp was ineffective against gonorrhea. Healthy vaccinee bias likely did not confound earlier studies of OMV vaccines.

IMPORTANCE: Because of historical associations between vaccines and Guillain-Barré syndrome (GBS), the condition was a prespecified adverse event of special interest for COVID-19 vaccine monitoring. OBJECTIVE: To evaluate GBS reports to the Vaccine Adverse Event Reporting System (VAERS) and compare reporting patterns within 21 and 42 days after vaccination with Ad26.COV2.S (Janssen), BNT162b2 (Pfizer-BioNTech), and mRNA-1273 (Moderna) COVID-19 vaccines. DESIGN, SETTING, AND PARTICIPANTS: This retrospective cohort study was conducted using US VAERS reports submitted during December 2020 to January 2022. GBS case reports verified as meeting the Brighton Collaboration case definition for GBS in US adults after COVID-19 vaccination were included. EXPOSURES: Receipt of the Ad26.COV2.S, BNT162b2, or mRNA-1273 COVID-19 vaccine. MAIN OUTCOMES AND MEASURES: Descriptive analyses of GBS case were conducted. GBS reporting rates within 21 and 42 days after Ad26.COV2.S, BNT162b2, or mRNA-1273 vaccination based on doses administered were calculated. Reporting rate ratios (RRRs) after receipt of Ad26.COV2.S vs BNT162b2 or mRNA-1273 within 21- and 42-day postvaccination intervals were calculated. Observed-to-expected (OE) ratios were estimated using published GBS background rates. RESULTS: Among 4 651 785 COVID-19 vaccine doses, 17 944 515 doses (3.7%) were Ad26.COV2.S, 266 859 784 doses (54.7%) were BNT162b2, and 202 847 486 doses (41.6%) were mRNA-1273. Of 295 verified reports of individuals with GBS identified after COVID-19 vaccination (12 Asian [4.1%], 18 Black [6.1%], and 193 White [65.4%]; 17 Hispanic [5.8%]; 169 males [57.3%]; median [IQR] age, 59.0 [46.0-68.0] years), 275 reports (93.2%) documented hospitalization. There were 209 and 253 reports of GBS that occurred within 21 days and 42 days of vaccination, respectively. Within 21 days of vaccination, GBS reporting rates per 1 000 000 doses were 3.29 for Ad26.COV.2, 0.29 for BNT162b2, and 0.35 for mRNA-1273 administered; within 42 days of vaccination, they were 4.07 for Ad26.COV.2, 0.34 for BNT162b2, and 0.44 for mRNA-1273. GBS was more frequently reported within 21 days after Ad26.COV2.S than after BNT162b2 (RRR = 11.40; 95% CI, 8.11-15.99) or mRNA-1273 (RRR = 9.26; 95% CI, 6.57-13.07) vaccination; similar findings were observed within 42 days after vaccination (BNT162b2: RRR = 12.06; 95% CI, 8.86-16.43; mRNA-1273: RRR = 9.27; 95% CI, 6.80-12.63). OE ratios were 3.79 (95% CI, 2.88-4.88) for 21-day and 2.34 (95% CI, 1.83-2.94) for 42-day intervals after Ad26.COV2.S vaccination and less than 1 (not significant) after BNT162b2 and mRNA-1273 vaccination within both postvaccination periods. CONCLUSIONS AND RELEVANCE: This study found disproportionate reporting and imbalances after Ad26.COV2.S vaccination, suggesting that Ad26.COV2.S vaccination was associated with increased risk for GBS. No associations between mRNA COVID-19 vaccines and risk of GBS were observed.

BACKGROUND: Risk of experiencing a systemic adverse event (AE) after mRNA coronavirus disease 2019 (COVID-19) vaccination may be greater among persons with a history of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection; data on serious events are limited. We assessed if adults reporting systemic AEs resulting in emergency department visits or hospitalizations during days 0-7 after mRNA COVID-19 vaccine dose 1 were more likely to have a history of prior SARS-CoV-2 infection compared with persons who reported no or non-severe systemic AEs. METHODS: We conducted a nested case-control study using v-safe surveillance data. Participants were18years and received dose 1 during December 14, 2020May 9, 2021. Cases reported severe systemic AEs 0-7days after vaccination. Three controls were frequency matched per case by age, vaccination date, and days since vaccination. Follow-up surveys collected SARS-CoV-2 histories. RESULTS: Follow-up survey response rates were 38.6% (potential cases) and 56.8% (potential controls). In multivariable analyses including 3,862 case-patients and 11,586 controls, the odds of experiencing a severe systemic AE were 2.4 (Moderna, mRNA-1273; 95% confidence interval [CI]: 1.89, 3.09) and 1.5 (Pfizer-BioNTech, BNT162b2; 95% CI: 1.17, 2.02) times higher among participants with pre-vaccination SARS-CoV-2 histories compared with those without. Medical attention of any kind for symptoms during days 0-7 following dose 2 was not common among case-patients or controls. CONCLUSIONS: History of SARS-CoV-2 infection was significantly associated with severe systemic AEs following dose 1 of mRNA COVID-19 vaccine; the effect varied by vaccine received. Most participants who experienced severe systemic AEs following dose 1 did not require medical attention of any kind for symptoms following dose 2. Vaccine providers can use these findings to counsel patients who had pre-vaccination SARS-CoV-2 infection histories, experienced severe systemic AEs following dose 1, and are considering not receiving additional mRNA COVID-19 vaccine doses.

The Advisory Committee on Immunization Practices (ACIP) recommends that all persons aged ≥5 years receive 1 booster dose of a COVID-19 vaccine after completion of their primary series.* On March 29, 2022, the Food and Drug Administration (FDA) authorized a second mRNA booster dose ≥4 months after receipt of a first booster dose for adults aged ≥50 years and persons aged ≥12 years with moderate to severe immunocompromise (1,2). To characterize the safety of a second mRNA booster dose among persons aged ≥50 years, CDC reviewed adverse events and health impact assessments reported to v-safe and the Vaccine Adverse Event Reporting System (VAERS) after receipt of a second mRNA booster dose during March 29-July 10, 2022. V-safe is a voluntary smartphone-based U.S. active surveillance system that monitors adverse events occurring after COVID-19 vaccination. VAERS is a U.S. passive surveillance system for monitoring adverse events after vaccination, managed by CDC and FDA (3). During March 29-July 10, 2022, approximately 16.8 million persons in the United States aged ≥50 years received a fourth dose.(†) Among 286,380 v-safe registrants aged ≥50 years who reported receiving a second booster of an mRNA vaccine, 86.9% received vaccines from the same manufacturer for all 4 doses (i.e., homologous vaccination). Among registrants who reported homologous vaccination, injection site and systemic reactions were less frequent after the second booster dose than after the first booster dose. VAERS received 8,515 reports of adverse events after second mRNA booster doses among adults aged ≥50 years, including 8,073 (94.8%) nonserious and 442 (5.1%) serious events. CDC recommends that health care providers and patients be advised that local and systemic reactions are expected after a second booster dose, and that serious adverse events are uncommon.

Persons with moderate to severe immunocompromising conditions are at risk for severe COVID-19, and their immune response to COVID-19 vaccination might not be as robust as the response in persons who are not immunocompromised* (1). The Advisory Committee on Immunization Practices (ACIP) recommends that immunocompromised persons aged ≥12 years complete a 3-dose primary mRNA COVID-19 vaccination series followed by a first booster dose (dose 4) ≥3 months after dose 3 and a second booster dose (dose 5) ≥4 months after dose 4.(†) To characterize the safety of first booster doses among immunocompromised persons aged ≥12 years during January 12, 2022-March 28, 2022, CDC reviewed adverse events and health impact assessments reported to v-safe and the Vaccine Adverse Event Reporting System (VAERS) during the week after receipt of an mRNA COVID-19 first booster dose. V-safe is a voluntary smartphone-based safety surveillance system for adverse events after COVID-19 vaccination. VAERS is a passive surveillance system for all vaccine-associated adverse events co-managed by CDC and the Food and Drug Administration (FDA). A fourth mRNA dose reported to v-safe or VAERS during January 12, 2022-March 28, 2022, was presumed to be an mRNA COVID-19 vaccine booster dose administered to an immunocompromised person because no other population was authorized to receive a fourth dose during that period (2,3). In the United States, during January 12, 2022-March 28, 2022, approximately 518,113 persons aged ≥12 years received a fourth dose. Among 4,015 v-safe registrants who received a fourth dose, local and systemic reactions were less frequently reported than were those following dose 3 of their primary series. VAERS received 145 reports after fourth doses; 128 (88.3%) were nonserious and 17 (11.7%) were serious. Health care providers, immunocompromised persons, and parents of immunocompromised children should be aware that local and systemic reactions are expected after a first booster mRNA COVID-19 vaccine dose, serious adverse events are rare, and safety findings were consistent with those previously described among nonimmunocompromised persons (4,5).

BACKGROUND AND OBJECTIVES: Limited post-authorization safety data for BNT-162b2 COVID-19 vaccination among children ages 5-11 years are available, particularly for the adverse event myocarditis, which has been detected in adolescents and young adults. We describe adverse events observed during the first 4 months of the US COVID-19 vaccination program in this age group. METHODS: We analyzed data from 3 US safety monitoring systems: v-safe, a voluntary smartphone-based system that monitors reactions and health effects; the Vaccine Adverse Events Reporting System (VAERS), the national spontaneous reporting system co-managed by CDC and FDA; and the Vaccine Safety Datalink (VSD), an active surveillance system that monitors electronic health records for prespecified events, including myocarditis. RESULTS: Among 48,795 children ages 5-11 years enrolled in v-safe, most reported reactions were mild-to-moderate, most frequently reported the day after vaccination, and were more common after dose 2. VAERS received 7,578 adverse event reports; 97% were non-serious. On review of 194 serious VAERS reports, 15 myocarditis cases were verified; 8 occurred in males after dose 2 (reporting rate 2.2 per million doses). In VSD, no safety signals were detected in weekly sequential monitoring after administration of 726,820 doses. CONCLUSIONS: Safety findings for BNT-162b2 vaccine from 3 US monitoring systems in children ages 5-11 years show that most reported adverse events were mild and no safety signals were observed in active surveillance. VAERS reporting rates of myocarditis after dose 2 in this age group were substantially lower than those observed among adolescents ages 12-15 years.

BACKGROUND: Declining antimicrobial susceptibility to current gonorrhoea antibiotic treatment and inadequate treatment options have raised the possibility of untreatable gonorrhoea. New prevention approaches, such as vaccination, are needed. Outer membrane vesicle meningococcal serogroup B vaccines might be protective against gonorrhoea. We evaluated the effectiveness of a serogroup B meningococcal outer membrane vesicle vaccine (MenB-4C) against gonorrhoea in individuals aged 16-23 years in two US cities. METHODS: We identified laboratory-confirmed gonorrhoea and chlamydia infections among individuals aged 16-23 years from sexually transmitted infection surveillance records in New York City and Philadelphia from 2016 to 2018. We linked gonorrhoea and chlamydia case records to immunisation registry records to determine MenB-4C vaccination status at infection, defined as complete vaccination (two MenB-4C doses administered 30-180 days apart), partial vaccination (single MenB-4C vaccine dose), or no vaccination (serogroup B meningococcal vaccine naive). Using log-binomial regression with generalised estimating equations to account for correlations between multiple infections per patient, we calculated adjusted prevalence ratios (APR) and 95% CIs to determine if vaccination was protective against gonorrhoea. We used individual-level data for descriptive analyses and infection-level data for regression analyses. FINDINGS: Between Jan 1, 2016, and Dec 31, 2018, we identified 167 706 infections (18 099 gonococcal infections, 124 876 chlamydial infections, and 24 731 gonococcal and chlamydial co-infections) among 109 737 individuals linked to the immunisation registries. 7692 individuals were vaccinated, of whom 4032 (52·4%) had received one dose, 3596 (46·7%) two doses, and 64 (<1·0%) at least three doses. Compared with no vaccination, complete vaccination series (APR 0·60, 95% CI 0·47-0·77; p<0·0001) and partial vaccination series (0·74, 0·63-0·88; p=0·0012) were protective against gonorrhoea. Complete MenB-4C vaccination series was 40% (95% CI 23-53) effective against gonorrhoea and partial MenB-4C vaccination series was 26% (12-37) effective. INTERPRETATION: MenB-4C vaccination was associated with a reduced gonorrhoea prevalence. MenB-4C could offer cross-protection against Neisseria gonorrhoeae. Development of an effective gonococcal vaccine might be feasible with implications for gonorrhoea prevention and control. FUNDING: None.

BACKGROUND: In December, 2020, two mRNA-based COVID-19 vaccines were authorised for use in the USA. We aimed to describe US surveillance data collected through the Vaccine Adverse Event Reporting System (VAERS), a passive system, and v-safe, a new active system, during the first 6 months of the US COVID-19 vaccination programme. METHODS: In this observational study, we analysed data reported to VAERS and v-safe during Dec 14, 2020, to June 14, 2021. VAERS reports were categorised as non-serious, serious, or death. Reporting rates were calculated using numbers of COVID-19 doses administered as the denominator. We analysed v-safe survey reports from days 0-7 after vaccination for reactogenicity, severity (mild, moderate, or severe), and health impacts (ie, unable to perform normal daily activities, unable to work, or received care from a medical professional). FINDINGS: During the study period, 298 792 852 doses of mRNA vaccines were administered in the USA. VAERS processed 340 522 reports: 313 499 (92·1%) were non-serious, 22 527 (6·6%) were serious (non-death), and 4496 (1·3%) were deaths. Over half of 7 914 583 v-safe participants self-reported local and systemic reactogenicity, more frequently after dose two (4 068 447 [71·7%] of 5 674 420 participants for local reactogenicity and 4 018 920 [70·8%] for systemic) than after dose one (4 644 989 [68·6%] of 6 775 515 participants for local reactogenicity and 3 573 429 [52·7%] for systemic). Injection-site pain (4 488 402 [66·2%] of 6 775 515 participants after dose one and 3 890 848 [68·6%] of 5 674 420 participants after dose two), fatigue (2 295 205 [33·9%] participants after dose one and 3 158 299 participants [55·7%] after dose two), and headache (1 831 471 [27·0%] participants after dose one and 2 623 721 [46·2%] participants after dose two) were commonly reported during days 0-7 following vaccination. Reactogenicity was reported most frequently the day after vaccination; most reactions were mild. More reports of being unable to work, do normal activities, or of seeking medical care occurred after dose two (1 821 421 [32·1%]) than after dose one (808 963 [11·9%]); less than 1% of participants reported seeking medical care after vaccination (56 647 [0·8%] after dose one and 53 077 [0·9%] after dose two). INTERPRETATION: Safety data from more than 298 million doses of mRNA COVID-19 vaccine administered in the first 6 months of the US vaccination programme show that most reported adverse events were mild and short in duration. FUNDING: US Centers for Disease Control and Prevention.

As of February 20, 2022, only BNT162b2 (Pfizer-BioNTech) COVID-19 vaccine has been authorized for use in persons aged 12-17 years in the United States (1). The Food and Drug Administration (FDA) amended the Emergency Use Authorization (EUA) for Pfizer-BioNTech vaccine on December 9, 2021, to authorize a homologous* booster dose for persons aged 16-17 years ≥6 months after receipt of dose 2 (1). On January 3, 2022, authorization was expanded to include persons aged 12-15 years, and for all persons aged ≥12 years, the interval between dose 2 and booster dose was shortened to ≥5 months (1). To characterize the safety of Pfizer-BioNTech booster doses among persons aged 12-17 years (adolescents), CDC reviewed adverse events and health impact assessments during the week after receipt of a homologous Pfizer-BioNTech booster dose reported to v-safe, a voluntary smartphone-based safety surveillance system for adverse events after COVID-19 vaccination, and adverse events reported to the Vaccine Adverse Event Reporting System (VAERS), a passive vaccine safety surveillance system managed by CDC and FDA. During December 9, 2021-February 20, 2022, approximately 2.8 million U.S. adolescents received a Pfizer-BioNTech booster dose.(†) During this period, receipt of 3,418 Pfizer-BioNTech booster doses were reported to v-safe for adolescents. Reactions were reported to v-safe with equal or slightly higher frequency after receipt of a booster dose than after dose 2, were primarily mild to moderate in severity, and were most frequently reported the day after vaccination. VAERS received 914 reports of adverse events after Pfizer-BioNTech booster dose vaccination of adolescents; 837 (91.6%) were nonserious and 77 (8.4%) were serious. Health care providers, parents, and adolescents should be advised that local and systemic reactions are expected among adolescents after homologous Pfizer-BioNTech booster vaccination, and that serious adverse events are rare.

Using meta-analytic methods, we calculated expected rates of 21 potential adverse events of special interest (AESI) that would occur following COVID-19 vaccination within 1-, 7-, and 42-day intervals without causal associations. Based on these expected rates, if 10,000,000 persons are vaccinated, 0.5, 3.7, and 22.5 Guillain-Barre syndrome cases; 0.3, 2.4, and 14.3 myopericarditis cases; and 236.5, 1655.5, and 9932.8 all-cause deaths would occur coincidentally within 1, 7, and 42 days post-vaccination, respectively. Expected rates of potential AESI can contextualize events associated temporally with immunization, aid in safety signal detection, guide COVID-19 vaccine health communications, and inform COVID-19 vaccine benefit-risk assessments.

As of July 30, 2021, among the three COVID-19 vaccines authorized for use in the United States, only the Pfizer-BioNTech BNT162b2 mRNA COVID-19 vaccine is authorized for adolescents aged 12-17 years. The Food and Drug Administration (FDA) issued an Emergency Use Authorization (EUA) for Pfizer-BioNTech vaccine for use in persons aged ≥16 years on December 11, 2020 (1); the EUA was expanded to include adolescents aged 12-15 years on May 10, 2021 (2), based on results from a Phase 3 clinical trial (3). Beginning in June 2021, cases of myocarditis and myopericarditis (hereafter, myocarditis) after receipt of Pfizer-BioNTech vaccine began to be reported, primarily among young males after receipt of the second dose (4,5). On June 23, 2021, CDC's Advisory Committee on Immunization Practices (ACIP) reviewed available data and concluded that the benefits of COVID-19 vaccination to individual persons and the population outweigh the risks for myocarditis and recommended continued use of the vaccine in persons aged ≥12 years (6). To further characterize safety of the vaccine, adverse events after receipt of Pfizer-BioNTech vaccine reported to the Vaccine Adverse Event Reporting System (VAERS) and adverse events and health impact assessments reported in v-safe (a smartphone-based safety surveillance system) were reviewed for U.S. adolescents aged 12-17 years during December 14, 2020-July 16, 2021. As of July 16, 2021, approximately 8.9 million U.S. adolescents aged 12-17 years had received Pfizer-BioNTech vaccine.* VAERS received 9,246 reports after Pfizer-BioNTech vaccination in this age group; 90.7% of these were for nonserious adverse events and 9.3% were for serious adverse events, including myocarditis (4.3%). Approximately 129,000 U.S. adolescents aged 12-17 years enrolled in v-safe after Pfizer-BioNTech vaccination; they reported local (63.4%) and systemic (48.9%) reactions with a frequency similar to that reported in preauthorization clinical trials. Systemic reactions were more common after dose 2. CDC and FDA continue to monitor vaccine safety and provide data to ACIP to guide COVID-19 vaccine recommendations.

BACKGROUND: Prospects for a gonococcal vaccine have advanced. Vaccine acceptability is crucial to maximizing population-level protection among key groups, such as men who have sex with men (MSM). We assessed prevalence of gonococcal vaccine acceptability among sexually-active MSM in the United States. METHODS: We used data from the American Men's Internet Study conducted during 8/2019─12/2019. We calculated frequencies of socio-demographic characteristics, vaccine acceptability, and preferred location for vaccine receipt. Using log-binomial regression analyses, we calculated unadjusted prevalence rates (PR) and 95% confidence intervals (CI) to evaluate factors associated with vaccine acceptability. RESULTS: Of 4,951 MSM, 83.5% were willing to accept a vaccine and 16.5% were unwilling. Preferred vaccination locations were primary care provider's clinics (83.5%) and sexually transmitted disease (STD) clinics (64.6%). Vaccine acceptability was greater among young MSM (15─24 years [PR = 1.09, 95% CI = 1.05-1.12], 25─29 years [PR = 1.13, 95% CI = 1.09─1.17], and 30-39 years [PR = 1.10, 95% CI = 1.05─1.14]) compared to MSM ≥ 40 years), MSM living with HIV (PR = 1.05, 95% CI = 1.02─1.09), and MSM who reported (in the past 12 months) condomless anal sex (PR = 1.09, 95% CI = 1.06─1.12), a bacterial STD test (PR = 1.18, 95% CI = 1.15─1.21), HIV pre-exposure prophylaxis use (PR = 1.17, 95% CI = 1.14─1.19), a bacterial STD diagnosis (PR = 1.04, 95% CI = 1.02─1.07), or a healthcare provider visit (PR = 1.11, 95% CI = 1.06─1.16). MSM who reported ≤high school education (PR = 0.93, 95% CI = 0.91-0.97) were less willing to accept a vaccine compared to those with >high school education. CONCLUSION: Most respondents were willing to accept a gonococcal vaccine. These findings can inform the planning and implementation of a future gonococcal vaccination program that focuses on MSM.

School closures affected more than 55 million students across the United States when implemented as a strategy to prevent the transmission of SARS-CoV-2, the virus that causes COVID-19 (1). Reopening schools requires balancing the risks for SARS-CoV-2 infection to students and staff members against the benefits of in-person learning (2). During December 3, 2020-January 31, 2021, CDC investigated SARS-CoV-2 transmission in 20 elementary schools (kindergarten through grade 6) that had reopened in Salt Lake County, Utah. The 7-day cumulative number of new COVID-19 cases in Salt Lake County during this time ranged from 290 to 670 cases per 100,000 persons.(†) Susceptible(§) school contacts(¶) (students and staff members exposed to SARS-CoV-2 in school) of 51 index patients** (40 students and 11 staff members) were offered SARS-CoV-2 reverse transcription-polymerase chain reaction (RT-PCR) testing. Among 1,041 susceptible school contacts, 735 (70.6%) were tested, and five of 12 cases identified were classified as school-associated; the secondary attack rate among tested susceptible school contacts was 0.7%. Mask use among students was high (86%), and the median distance between students' seats in classrooms was 3 ft. Despite high community incidence and an inability to maintain ≥6 ft of distance between students at all times, SARS-CoV-2 transmission was low in these elementary schools. The results from this investigation add to the increasing evidence that in-person learning can be achieved with minimal SARS-CoV-2 transmission risk when multiple measures to prevent transmission are implemented (3,4).

PURPOSE: Prescription opioid misuse is associated with behaviors which increase bacterial sexually transmitted diseases (STD) risk among men who have sex with men (MSM). Annual syphilis, gonorrhea, and chlamydia screening is recommended for sexually active MSM at anatomical sites of contact, regardless of condom use. We describe the prevalence of self-reported bacterial STD testing and diagnoses in the past 12 months among sexually active MSM who report prescription opioid misuse. METHODS: We used data from the 2017 and 2018 American Men's Internet Survey to examine the prevalence of self-reported bacterial STD testing and diagnoses in the past 12 months. We calculated unadjusted prevalence ratios, adjusted prevalence ratios (APR), and 95% confidence intervals (CI) to compare bacterial STD testing prevalence across demographic, clinical, and behavioral factors. RESULTS: Of 932 sexually active MSM who reported prescription opioid misuse, 433 (46.5%) self-reported bacterial STD testing in the past 12 months. Of those who reported being tested, 131 (30.2%) self-reported ≥ 1 bacterial STD. Approximately 50% of respondents who reported condomless anal sex (CAS), casual sex, or exchange sex reported bacterial STD testing in past 12 months. Factors associated with bacterial STD testing among MSM who misused prescription opioids included visiting a healthcare provider in the past 12 months (APR=1.70, 95% CI=1.09-2.67), ever disclosing same-sex behavior to a healthcare provider (APR=1.78, 95% CI=1.27-2.50), and CAS in the past 12 months (APR=1.51, 95% CI=1.10-2.04). CONCLUSIONS: Prevalence of self-reported bacterial STD testing in this sample was low and one-third of tested MSM reported ≥ 1 bacterial STD in the past 12 months. Innovative approaches to identify MSM who misuse prescription opioids and expand bacterial STD testing in this population are needed.

Declining gonococcal susceptibility to ceftriaxone and azithromycin has raised the possibility of untreatable gonorrhea in the future and re-ignited interest in gonococcal vaccine development. Despite decades of research, previous gonococcal vaccine candidates have been ineffective. A growing body of data suggest that meningococcal group B outer membrane vaccines (MenB OMV) may be cross-protective against Neisseria gonorrhoeae. Clinical trials of a licensed vaccine against N. meningitidis serogroup B containing an OMV component are underway to determine its efficacy against N. gonorrhoeae. Other experimental gonococcal vaccine candidates are in the preclinical phases. Population impact of future gonococcal vaccines with different levels of efficacy and duration of protection in various populations are being evaluated using modeling studies. Despite recent progress, gaps in gonococcal vaccine research remain. Research is needed to evaluate vaccine efficacy in preventing gonococcal infections acquired via various anatomic routes and among patients co-infected with other sexually transmitted infections. Studies that model the impact of a future vaccine on high-burden populations such as men who have sex with men and estimate both vaccine cost-effectiveness and the incremental cost-effectiveness ratio of vaccination to antimicrobial resistance and treatment costs are warranted. This narrative review examines the current state of gonococcal vaccine research, the possible impact of a gonococcal vaccine on gonorrhea rates based on modeling studies, gaps in the gonococcal vaccine literature, and public health implications of a future gonococcal vaccine on reducing the gonorrhea burden in the United States.

BACKGROUND: Extragenital gonorrhea (GC) and chlamydia (CT) are usually asymptomatic and only detected through screening. Ceftriaxone plus azithromycin is the recommended GC treatment; monotherapy (azithromycin or doxycycline) is recommended for CT. In urethral CT-positive/urethral GC-negative persons who are not screened extragenitally, CT monotherapy can lead to GC undertreatment and may foster the development of gonococcal antimicrobial resistance. We assessed urethral and extragenital GC and CT positivity among men who have sex with men (MSM) attending sexually transmitted disease (STD) clinics. METHODS: We included visit data for MSM tested for GC and CT at 30 STD clinics in 10 jurisdictions during 1/1/2015-6/30/2019. Using an inverse-variance random effects model to account for heterogeneity between jurisdictions, we calculated weighted test visit positivity estimates and 95% confidence intervals (CI) for GC and CT at urethral and extragenital sites, and extragenital GC among urethral CT-positive/GC-negative test visits. RESULTS: Of 139,718 GC and CT test visits, we calculated overall positivity (GC=16.7% [95% CI=14.4-19.1]; CT=13.3% [95% CI=12.7-13.9]); urethral positivity (GC=7.5% [95% CI=5.7-9.3]; CT=5.2% [95% CI=4.6-5.8]); rectal positivity (GC=11.8% [95% CI=10.4-13.2]; CT=12.6% [95% CI=11.8-13.4]); and pharyngeal positivity (GC=9.1% [95% CI=7.9-10.3]; CT=1.8% [95% CI=1.6-2.0]). Of 4,566 urethral CT-positive/GC-negative test visits with extragenital testing, extragenital GC positivity was 12.5% (95% CI=10.9-14.1). CONCLUSION: Extragenital GC and CT were common among MSM. Without extragenital screening of MSM with urethral CT, extragenital GC would have been undetected and undertreated in ~13% of these men. Undertreatment could potentially select for antimicrobial resistance. These findings underscore the importance of extragenital screening in MSM.

BACKGROUND: Extragenital gonorrhea (GC) and chlamydia (CT) are usually asymptomatic and only detected through screening. Ceftriaxone plus azithromycin is the recommended GC treatment; monotherapy (azithromycin or doxycycline) is recommended for CT. In urethral CT-positive/urethral GC-negative persons who are not screened extragenitally, CT monotherapy can lead to GC undertreatment and may foster the development of gonococcal antimicrobial resistance. We assessed urethral and extragenital GC and CT positivity among men who have sex with men (MSM) attending sexually transmitted disease (STD) clinics. METHODS: We included visit data for MSM tested for GC and CT at 30 STD clinics in 10 jurisdictions during 1/1/2015-6/30/2019. Using an inverse-variance random effects model to account for heterogeneity between jurisdictions, we calculated weighted test visit positivity estimates and 95% confidence intervals (CI) for GC and CT at urethral and extragenital sites, and extragenital GC among urethral CT-positive/GC-negative test visits. RESULTS: Of 139,718 GC and CT test visits, we calculated overall positivity (GC=16.7% [95% CI=14.4-19.1]; CT=13.3% [95% CI=12.7-13.9]); urethral positivity (GC=7.5% [95% CI=5.7-9.3]; CT=5.2% [95% CI=4.6-5.8]); rectal positivity (GC=11.8% [95% CI=10.4-13.2]; CT=12.6% [95% CI=11.8-13.4]); and pharyngeal positivity (GC=9.1% [95% CI=7.9-10.3]; CT=1.8% [95% CI=1.6-2.0]). Of 4,566 urethral CT-positive/GC-negative test visits with extragenital testing, extragenital GC positivity was 12.5% (95% CI=10.9-14.1). CONCLUSION: Extragenital GC and CT were common among MSM. Without extragenital screening of MSM with urethral CT, extragenital GC would have been undetected and undertreated in ~13% of these men. Undertreatment could potentially select for antimicrobial resistance. These findings underscore the importance of extragenital screening in MSM.

PURPOSE: We investigated the association between county-level trends in opioid prescribing rates, a proxy for opioid misuse, and rates of reported gonorrhea (GC) among males in the United States. METHODS: We used linear mixed-model regression analyses to evaluate the association between county-level trends in opioid prescribing rates and rates of reported GC among males during 2010-2015. RESULTS: There was a positive association between trends in county-level opioid prescribing rates and rates of GC among males (beta = 0.068, 95% confidence interval [CI] = 0.030, 0.105) during 2010-2015. However, the magnitude of this association decreased significantly over time in counties where opioid prescribing rates decreased (beta = -0.018, 95% CI = -0.030, -0.006) and remained stable (beta = -0.020, 95% CI = -0.038, -0.002) but was unchanged in counties where opioid prescribing rates increased (beta = -0.029, 95% CI = -0.058, 0.001). CONCLUSIONS: During 2010-2015, we found a positive association between increases in county-level opioid prescribing rates, a proxy for opioid misuse, and rates of reported GC among males especially in counties most affected by the opioid crisis. Integrating sexual health with opioid misuse interventions might be beneficial in addressing the GC burden in the United States.

BACKGROUND: Six-monthly hepatocellular carcinoma (HCC) screening in cirrhotic patients has been recommended since 2011. HCC prognosis is associated with diagnosis at an early stage. We examined the prevalence and correlates of 6-monthly HCC surveillance in a cohort of HCV-infected cirrhotic patients. METHODS: Data were obtained from the medical records of patients receiving care from four hospitals between January 2011 and December 2016. Frequencies and logistic regression were conducted. RESULTS: Of 2,933 HCV-infected cirrhotic patients, most were >/= 60 years old (68.5%), male (62.2%), White (65.8%), and had compensated cirrhosis (74.2%). The median follow-up period was 3.5 years. Among these patients, 10.9% were consistently screened 6 monthly and 21.4% were never screened. Patients with a longer history of cirrhosis (AOR = 0.86, 95% CI = 0.80-0.93) were less likely to be screened 6 monthly while decompensated cirrhotic patients (AOR = 1.39, 95% CI = 1.06-1.81) and cirrhotic patients between 18 and 44 years (AOR = 2.01, 95% CI = 1.07-3.74) were more likely to be screened 6 monthly compared to compensated cirrhotic patients and patients 60 years and older respectively. There were no significant differences by race, gender, or insurance type. CONCLUSION: The prevalence of consistent HCC surveillance remains low despite formalized recommendations. One in five patients was never surveilled. Patients with a longer history of cirrhosis were less likely to be surveilled consistently despite their greater HCC risk. Improving providers' knowledge about current HCC surveillance guidelines, educating patients about the benefits of consistent HCC surveillance, and systemic interventions like clinical reminders and standing HCC surveillance protocols can improve guideline-concordant surveillance in clinical practice.

INTRODUCTION: Historically, older people who inject drugs (PWID) have had the highest hepatitis C burden, however, young PWID account for recent increases in HCV infection. We assessed factors associated with past or present HCV infection (HCV antibody-positive) among young (</=35 years) and older PWID (>35 years). METHODS: Using Poisson regression, we calculated adjusted prevalence ratios (aPR) to examine socio-demographic and past 12-month injection risk behaviors associated with HCV infection. RESULTS: Of 4,094 PWID, 55.2% were HCV antibody-positive (anti-HCV). Among young PWID, anti-HCV prevalence was 42.1% and associated with </=high school diploma/GED (aPR=1.17, 95%CI=1.03-1.32), receptive syringe sharing (aPR=1.37, 95%CI=1.21-1.56), sharing injection equipment (aPR=1.16, 95%CI=1.01-1.35), arrest history (aPR=1.14, 95%CI=1.02-1.29), and injecting speedball (aPR=1.37, 95%CI=1.16-1.61). Among older PWID, anti-HCV prevalence was 62.2% and associated with </=high school diploma/GED (aPR= 1.08, 95%CI=1.02-1.15), sharing injection equipment (aPR=1.08, 95% CI=1.02-1.15), high injection frequency (aPR=1.16, 95%CI=1.01-1.34), and injecting speedball (aPR=1.09, 95%CI=1.01-1.16). CONCLUSION: Anti-HCV positivity prevalence is high and associated with risky injection practices. Almost half of young PWID were anti-HCV positive. Improving access to direct-acting antiviral treatment, syringe service programs, and medication-assisted therapy are critical to reducing HCV transmission risk and infection burden, particularly among young PWID who are more likely to be newly infected.