(347) Interim Utilization Results from a Post-Approval Safety Study of Pfizer-BioNTech Monovalent COVID-19 Vaccine in the United States

Background: A post-approval safety study of Pfizer-BioNTech original monovalent COVID-19 vaccine (BNT162b2) is underway in the United States using data from 5 research partners (RPs) participating in the Sentinel System, supplemented with immunization information system (IIS) vaccine data, where available. As part of the interim analysis, COVID-19 vaccine capture and utilization were assessed.

Objectives: To characterize capture and utilization of at least 1 monovalent COVID-19 vaccine of any brand (“COVID-19 vaccine”) and of BNT162b2 and to describe subsequent doses among BNT162b2 vaccinees.

Methods: Analyses included data from December 2020 through July 2023. Among those eligible to receive BNT162b2 and enrolled since earliest eligibility, we estimated the cumulative incidence (CI) of receipt of at least 1 COVID-19 vaccine and receipt of at least 1, 2, and 3 doses of BNT162b2. Competing events were mortality, receipt of other/unknown brand or updated COVID-19 vaccines, or of BNT162b2 >4 days before the recommended dosing interval (“too early”). The CI estimates for receipt of at least 1 COVID-19 vaccine was compared to estimates from previous monitoring analyses that did not include IIS data. Among BNT162b2 vaccinees, we assessed subsequent dose brand and timing. All analyses were repeated within age subgroups.

Results: During the study observation period, >15.3 million 1st doses of COVID-19 vaccine were observed, including >8.9 million BNT162b2 doses. Less than 0.1% of BNT162b2 doses were received outside authorized age groups. Most BNT162b2 vaccinees (83%) received a 2nd dose of COVID-19 vaccine, of which 99% were BNT162b2. Less than 1% of 2nd BNT162b2 doses were received too early. Among the >7.3 million individuals who received 2 doses of BNT162b2, 49% had a 3rd COVID-19 vaccine dose, of which 91% were BNT162b2. The CI of receiving at least 1 COVID-19 vaccine and at least 1 BNT162b2 dose was 68% and 40%, respectively, through July 2023. CI of receipt of at least 1 COVID-19 vaccine was 65-70% among those aged 12+ years, 40% among those 5-11 years and 19% among those aged 6 months-4 years. Among those aged 5-17 years, BNT162b2 accounted for >96% of 1st COVID-19 vaccine doses; the proportion was lower for other age groups (49-61%). Relative to previous monitoring analyses, incorporating IIS data resulted in 1.72 times higher measured vaccine coverage through October 2021. Coverage estimates were comparable to those produced by the Centers for Disease Control and Prevention (CDC).

Conclusions: The capture of 1st COVID-19 vaccine and BNT162b2 doses observed in this interim analysis support the sample size needed for final safety analyses of BNT162b2 and the use of an unvaccinated comparator group. Most BNT162b2 vaccinations were given as recommended by the CDC.