METHODS
infection
SARS-COV-2 INFECTION, ADVERSE EVENT, BLOOD, INFECTION, EVENTS, APPENDIX
In this ongoing study, existing 5- to 11-year-old participants from a phase 2/3 study (NCT04816643) who received two 10-µg BNT162b2 doses given 21 days apart received an open-label third (booster) dose of 10-µg BNT162b2 at least 6 months after dose 2. The dose level of BNT162b2 doses 2 and 3 was based on the participant’s age at the time of vaccination. Therefore, participants who were 12 years old at the time of receiving the third dose are not included in this analysis as they received the recommended age-appropriate 30-µg dose level. Eligibility criteria, ethical study conduct, and study responsibilities are summarized in the Appendix.Safety evaluations included assessment of participant- or parent/legal guardian-reported local reactions, systemic events, and antipyretic use recorded in an electronic diary for up to 7 days after dose 3. Adverse event (AE) reports were collected from dose 3 through 1 month after dose 3. Serious AEs are being collected from dose 3 through approximately 6 months after dose 3.In this analysis, the main immunogenicity assessments were conducted in participants without prior SARS-CoV-2 infection (see Appendix for determination of prior infection status). Assessments were also conducted in participants with and without prior SARS-CoV-2 infection. Blood samples were collected for immunogenicity assessments, which included determination of SARS-CoV-2 neutralization titers with a validated assay using the ancestral (USA-WA1/2020) strain as described previously and with a non-validated Fluorescent Focus Reduction Neutralization Test (FFRNT) against Omicron BA.1 and BA.4/BA.5 lineages [