Risk of Adverse Events Following Monovalent Third or Booster Dose of COVID-19 mRNA Vaccination in U.S. Adults Ages 18 Years and Older (preprint)

Background: The U.S. FDA authorized the monovalent third primary series or booster doses of COVID-19 mRNA vaccines in August 2021 for persons 18 years and older. Monitoring of outcomes following updated authorizations is critical to evaluate vaccine safety and can provide early detection of rare adverse events (AEs) not identified in pre-licensure trials. Methods We evaluated the risk of 17 AEs following third doses of COVID-19 mRNA vaccines from August 2021 through early 2022 among adults aged 18-64 years in three commercial databases (Optum, Carelon Research, CVS Health) and adults aged >65 years in Medicare Fee-For-Service. We compared observed AE incidence rates to historical (expected) rates prior to the pandemic, estimated incidence rate ratios (IRRs) for the Medicare database and pooled IRR across the three commercial databases. Analyses were also stratified by prior history of COVID-19 diagnosis. Estimates exceeding a pre-defined threshold were considered statistical signals. Results Four AEs met the threshold for statistical signals for BNT162b2 and mRNA-1273 vaccines including Bells Palsy and pulmonary embolism in Medicare, and anaphylaxis and myocarditis/pericarditis in commercial databases. Nine AEs and three AEs signaled among adults with and without prior COVID-19 diagnosis, respectively. Conclusions This early monitoring study identified statistical signals for AEs following third doses of COVID-19 mRNA vaccination. Since this method is intended for screening purposes and generates crude results, results do not establish a causal association between the vaccines and AEs. FDAs public health assessment remains consistent that the benefits of COVID-19 vaccination outweigh the risks of vaccination.

Safety Monitoring of Bivalent COVID-19 mRNA Vaccines Among Recipients 6 months and Older in the United States (preprint)

Importance Active monitoring of health outcomes after COVID-19 vaccination provides early detection of rare outcomes post-licensure. Objective To evaluate health outcomes following bivalent COVID-19 Pfizer-BioNTech (BNT162b2) and Moderna (mRNA-1273.222) vaccination among individuals 6 months and older in the United States. Design Monthly monitoring of health outcomes from August 2022 to July 2023 in four administrative claims databases. Descriptive analyses monitored vaccine uptake, outcome counts and coadministration of bivalent COVID-19 and influenza vaccines. Sequential analyses tested for elevated risk of each outcome in a prespecified post-vaccination risk interval, or a period of hypothesized elevation based on clinical guidance, compared to a historical baseline. Participants and Exposures Persons 6 months and older who received a bivalent COVID-19 BNT162b2 or mRNA-1273.222 vaccine during the study period, with continuous enrollment in a medical insurance plan from the start of an outcome-specific clean interval to the COVID-19 vaccination date. Vaccines were identified using product-specific codes from medical coding systems. Health Outcomes Twenty outcomes were monitored in BNT162b2 vaccine recipients 6 months-4 years, and mRNA-1273.222 vaccine recipients 6 months-5 years. Twenty-one outcomes were monitored in BNT162b2 vaccine recipients 5-17 years and mRNA-1273.222 vaccine recipients 6-17 years. Eighteen outcomes were monitored in persons 18 years and older for both mRNA vaccines. Results Overall, 13.9 million individuals 6 months and older received a single bivalent COVID-19 mRNA vaccine. The statistical threshold for a signal was met for two outcomes in one database: anaphylaxis following bivalent BNT162b2 and mRNA-1273.222 vaccines in persons 18-64 years and myocarditis/pericarditis following bivalent BNT162b2 vaccines in individuals 18-35 years. There were no signals identified in young children. Conclusions Results were consistent with prior observations from published studies on COVID-19 vaccine safety. This study supports the safety profile of bivalent COVID-19 mRNA vaccines and the conclusion that the benefits of vaccination outweigh the risks.

Safety of Monovalent BNT162b2 (Pfizer-BioNTech), mRNA-1273 (Moderna), and NVX-CoV2373 (Novavax) COVID-19 Vaccines in US Children Aged 6 months to 17 years (preprint)

Importance Active monitoring of health outcomes after COVID-19 vaccination provides early detection of rare outcomes that may not be identified in prelicensure trials. Objective To conduct near-real-time monitoring of health outcomes following COVID-19 vaccination in the United States (US) pediatric population aged 6 months to 17 years. Design We evaluated 21 pre-specified health outcomes; 15 were sequentially tested through near-real-time surveillance, and 6 were monitored descriptively within a cohort of vaccinated children. We tested for increased rate of each outcome following vaccination compared to a historical comparator cohort. Setting This population-based study was conducted under the US Food and Drug Administration public health surveillance mandate using three commercial claims databases. Participants Children aged 6 months to 17 years were included if they received a monovalent COVID-19 vaccine dose before early 2023 and had continuous enrollment in a medical health insurance plan from the start of an outcome-specific clean window to the COVID-19 vaccination dose. Exposure Exposure was defined as receipt of a monovalent BNT162b2, mRNA-1273, or NVX-CoV2373 COVID-19 vaccine dose. The primary analysis evaluated dose 1 and dose 2 combined, and secondary analyses evaluated each dose separately. Follow-up time was censored at death, disenrollment, end of risk window, end of study period, or a subsequent dose administration. Main Outcomes Twenty-one prespecified health outcomes. Results The study included 4,102,016 enrollees aged 6 months to17 years. Thirteen of 15 outcomes sequentially tested did not meet the threshold for a statistical signal. In the primary analysis, myocarditis or pericarditis signals were detected following BNT162b2 vaccine in children aged 12-17 years old and seizures/convulsions signals were detected following vaccination with BNT162b2 and mRNA-1273 in children aged 2-4/5 years. However, in a post-hoc sensitivity analysis, the seizures/convulsions signal was sensitive to background rates selection and was not observed when 2022 background rates were selected instead of 2020 rates. Conclusions and Relevance Of the two signaled outcomes, the myocarditis or pericarditis signals are consistent with previously published reports. The new signal detected for seizures/convulsions among younger children should be further investigated in a robust epidemiological study with better confounding adjustment.

Effectiveness of BNT162b2 COVID-19 Vaccination in Children Aged 5-17 Years in the United States (preprint)

Importance: COVID-19 vaccines are authorized for use in children in the United States; real-world assessment of vaccine effectiveness in children is needed. Objective: To estimate the effectiveness of receiving a complete primary series of monovalent BNT162b2 (Pfizer-BioNTech) COVID-19 vaccine in US children. Design: A cohort study of children aged 5--17 years vaccinated with BNT162b2 matched with unvaccinated children. Setting: Participants identified in Optum and CVS Health insurance administrative claims databases were linked with Immunization Information System (IIS) COVID-19 vaccination records from 16 US jurisdictions between December 11, 2020, and May 31, 2022 (end date varied by database and IIS). Participants: Vaccinated children were followed from their first BNT162b2 dose and matched to unvaccinated children on calendar date, US county of residence, and demographic and clinical factors. Censoring occurred if vaccinated children failed to receive a timely dose 2 or if unvaccinated children received any dose. Exposure: BNT162b2 vaccinations were identified using IIS vaccination records and insurance claims. Main Outcomes and Measures: Two COVID-19 outcome definitions were evaluated: COVID-19 diagnosis in any medical setting and COVID-19 diagnosis in hospitals/emergency departments (EDs). Propensity score-weighted hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated with Cox proportional hazards models, and vaccine effectiveness (VE) was estimated as 1 minus HR. VE was estimated overall, within age subgroups, and within variant-specific eras. Sensitivity, negative control, and quantitative bias analyses evaluated various potential biases. Results: There were 453,655 eligible vaccinated children one-to-one matched to unvaccinated comparators (mean age 12 years; 50% female). COVID-19 hospitalizations/ED visits were rare in children, regardless of vaccination status (Optum, 41.2 per 10,000 person- years; CVS Health, 44.1 per 10,000 person- years). Overall, vaccination was associated with reduced incidence of any medically diagnosed COVID-19 (meta-analyzed VE = 38% [95% CI, 36%-40%]) and hospital/ED-diagnosed COVID-19 (meta-analyzed VE = 61% [95% CI, 56%-65%]). VE estimates were lowest among children 5--11 years and during the omicron variant era. Conclusions and Relevance: Receipt of a complete BNT162b2 vaccine primary series was associated with overall reduced medically diagnosed COVID-19 and hospital/ED-diagnosed COVID-19 in children; observed VE estimates differed by age group and variant era.

Evaluation of Potential Adverse Events Following COVID-19 mRNA Vaccination Among Adults Aged 65 Years and Older: A Self-Controlled Study in the U.S. (preprint)

Background Our near-real-time safety monitoring of 16 adverse events (AEs) following COVID-19 mRNA vaccination identified potential elevations in risk for six AEs following primary series and monovalent booster dose administration. The crude association with AEs does not imply causality. Accordingly, we conducted robust evaluations of the potential associations. Methods We conducted self-controlled case series studies of COVID-19 mRNA vaccines (BNT162b2 and mRNA-1273) in U.S. Medicare beneficiaries aged 65 years and older. Adjusted incidence rate ratio (IRRs) and 95% confidence intervals (CIs) were estimated following primary series doses for acute myocardial infarction (AMI), pulmonary embolism (PE), immune thrombocytopenia (ITP), disseminated intravascular coagulation (DIC); and following booster doses for AMI, PE, ITP, Bells Palsy (BP) and Myocarditis/Pericarditis (Myo/Peri). Results Among 3,360,981 individuals who received 6,388,542 primary series doses and 6,156,100 individuals with monovalent booster doses of either BNT162b2 or mRNA-1273, AE counts were: AMI (3,653 primary series, 16,042 booster), inpatient PE (2,470 primary, 5,085 booster), ITP (1,085 primary, 88 booster), DIC (254 primary), BP (3,268 booster), and Myo/Peri (1,295 booster). The IRR for inpatient PE cases following BNT162b2 primary series and booster was 1.19 (95% CI: 1.03 to 1.38) and 0.86 (95% CI: 0.78 to 0.95), respectively; and for mRNA-1273 primary series and booster, 1.15 (95% CI: 0.94 to 1.41) and 0.87 (95% CI: 0.79 to 0.96), respectively. The IRR for BP following BNT162b2 and mRNA-1273 booster was 1.17 (95% CI: 1.06 to 1.29) and 1.16 (95% CI: 1.05 to 1.29), respectively. Conclusion In these two studies of the U.S. elderly we did not find an increased risk for AMI, ITP, DIC, and Myo/Peri; the results were not consistent for PE; and there was a small elevated risk of BP after exposure to COVID-19 mRNA vaccines. These results support the favorable safety profile of COVID-19 mRNA vaccines administered in the elderly.

Surveillance of COVID-19 vaccine safety among elderly persons aged 65 years and older (preprint)

Background: Monitoring safety outcomes following COVID-19 vaccination is critical for understanding vaccine safety especially when used in key populations such as elderly persons age 65 years and older who can benefit greatly from vaccination. We present new findings from a nationally representative early warning system that may expand the safety knowledge base to further public trust and inform decision making on vaccine safety by government agencies, healthcare providers, interested stakeholders, and the public. Methods: We evaluated 14 outcomes of interest following COVID-19 vaccination using the US Centers for Medicare & Medicaid Services (CMS) data covering 30,712,101 elderly persons. The CMS data from December 11, 2020 through Jan 15, 2022 included 17,411,342 COVID-19 vaccinees who received a total of 34,639,937 doses. We conducted weekly sequential testing and generated rate ratios (RR) of observed outcome rates compared to historical (or expected) rates prior to COVID-19 vaccination. Findings: Four outcomes met the threshold for a statistical signal following Pfizer-BioNTech vaccination including pulmonary embolism (PE; RR=1.54), acute myocardial infarction (AMI; RR=1.42), disseminated intravascular coagulation (DIC; RR=1.91), and immune thrombocytopenia (ITP; RR=1.44). After further evaluation, only the RR for PE still met the statistical threshold for a signal; however, the RRs for AMI, DIC, and ITP no longer did. No statistical signals were identified following vaccination with either the Moderna or Janssen vaccines. Interpretation: This early warning system is the first to identify temporal associations for PE, AMI, DIC, and ITP following Pfizer-BioNTech vaccination in the elderly. Because an early warning system does not prove that the vaccines cause these outcomes, more robust epidemiologic studies with adjustment for confounding factors, including age and nursing home residency, are underway to further evaluate these signals. FDA strongly believes the potential benefits of COVID-19 vaccination outweigh the potential risks of COVID-19 infection.

Results of safety monitoring of BNT162b2 (Pfizer-BioNTech) COVID-19 vaccine in U.S. children aged 5-17 years (preprint)

Importance: Active monitoring of health outcomes following COVID-19 vaccination offers early detection of rare outcomes that may not be identified in pre-licensure trials. Objective: To conduct near-real time monitoring of health outcomes following BNT162b2 COVID-19 vaccination in the U.S. pediatric population aged 5-17 years. Design: We conducted rapid cycle analysis of 20 pre-specified health outcomes, 13 of which underwent sequential testing and 7 of which were monitored descriptively within a cohort of vaccinated individuals. We tested for increased risk of each health outcome following vaccination compared to a historical baseline, while adjusting for repeated looks at the data as well as claims processing delay. Setting: This is a population-based study in three large commercial claims databases conducted under the U.S. FDA public health surveillance mandate. Participants: The study included over 3 million enrollees aged 5-17 years with BNT162b2 COVID-19 vaccination through mid-2022 in three commercial claims databases. We required continuous enrollment in a medical health insurance plan from the start of an outcome-specific clean window to the COVID-19 vaccination. Exposure: Exposure was defined as receipt of a BNT162b2 COVID-19 vaccine dose. The primary analysis assessed primary series doses together (Dose 1 + Dose 2), and dose-specific secondary analyses were conducted. Follow up time was censored for death, disenrollment, end of risk window, end of study period, or a subsequent vaccine dose. Main Outcome(s) and Measure(s): We monitored 20 pre-specified health outcomes. We performed descriptive monitoring for all outcomes and sequential testing for 13 outcomes. Results: Among 13 health outcomes evaluated by sequential testing, 12 did not meet the threshold for a statistical signal in any of the three databases. In our primary analysis, myocarditis/pericarditis signaled following primary series vaccination with BNT162b2 in ages 12-17 years across all three databases. Conclusions and Relevance: Consistent with published literature, our near-real time monitoring identified a signal for only myocarditis/pericarditis following BNT162b2 COVID-19 vaccination in children aged 12-17 years. This method is intended for early detection of safety signals. Our results are reassuring of the safety of the vaccine, and the potential benefits of vaccination outweigh the risks.