{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,29]],"date-time":"2026-09-29T10:20:44Z","timestamp":1790677244648,"version":"4.1.0"},"reference-count":30,"publisher":"American Medical Association (AMA)","issue":"12","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JAMA Netw Open"],"abstract":"Importance<\/jats:title>Data describing the vaccine effectiveness (VE) and durability of BNT162b2 among children 5 to 11 years of age are needed.<\/jats:p><\/jats:sec>Objective<\/jats:title>To estimate BNT162b2 VE against SARS-CoV-2 infection among children aged 5 to 11 years during Delta and Omicron variant\u2013predominant periods and to further assess VE according to prior SARS-CoV-2 infection status and by sublineage during the Omicron variant\u2013predominant period.<\/jats:p><\/jats:sec>Design, Setting, and Participants<\/jats:title>This test-negative case-control study was conducted from November 2 to December 9, 2021 (Delta variant), and from January 16 to September 30, 2022 (Omicron variant), among 160\u202f002 children tested at a large national US retail pharmacy chain, for SARS-CoV-2 via polymerase chain reaction (PCR); 62\u202f719 children were tested during the Delta period, and 97\u202f283 were tested during the Omicron period.<\/jats:p><\/jats:sec>Exposure<\/jats:title>Vaccination with BNT162b2 before SARS-CoV-2 testing vs no vaccination.<\/jats:p><\/jats:sec>Main Outcomes and Measures<\/jats:title>The primary outcome was SARS-CoV-2 infection confirmed by PCR (regardless of the presence of symptoms), and the secondary outcome was confirmed symptomatic infection. Adjusted estimated VE was calculated from multilevel logistic regression models.<\/jats:p><\/jats:sec>Results<\/jats:title>A total of 39\u202f117 children tested positive and 131\u202f686 tested negative for SARS-CoV-2 (total, 170\u202f803; 84\u202f487 [49%] were boys; mean [SD] age was 9 [2] years; 74\u202f236 [43%] were White non-Hispanic or non-Latino; and 37\u202f318 [22%] were Hispanic or Latino). Final VE analyses included 160\u202f002 children without SARS-CoV-2 infection less than 90 days prior. The VE of 2 doses of BNT162b2 against Delta was 85% (95% CI, 80%-89%; median follow-up, 1 month) compared with the Omicron period (20% [95% CI, 17%-23%]; median follow-up, 4 months). The adjusted VE of 2 doses against Omicron at less than 3 months was 39% (95% CI, 36%-42%), and at 3 months or more, it was \u22121% (95% CI, \u22126% to 3%). Protection against Omicron was higher among children with vs without infection 90 days or more prior but decreased in all children approximately 3 months after the second dose (58% [95% CI, 49%-66%] with infection vs 37% [95% CI, 34%-41%] without infection at &amp;lt;3 months; 27% [95% CI, 17%-35%] with infection vs \u22127% [95% CI, \u221212% to \u22121%] at \u22653 months without infection). The VE of 2 doses of BNT162b2 at less than 3 months by Omicron sublineage was 40% (95% CI, 36%-43%) for BA.1, 32% (95% CI, 21%-41%) for BA.2\/BA.2.12.1, and 50% (95% CI, 37%-60%) for BA.4\/BA.5. After 3 months or more, VE was nonsignificant for BA.2\/BA.2.12.1 and BA.4\/BA.5. The VE of a booster dose was 55% (95% CI, 50%-60%) against Omicron, with no evidence of waning at 3 months or more.<\/jats:p><\/jats:sec>Conclusions and Relevance<\/jats:title>This study suggests that, among children aged 5 to 11 years, 2 doses of BNT162b2 provided modest short-term protection against Omicron infection that was higher for those with prior infection; however, VE waned after approximately 3 months in all children. A booster dose restored protection against Omicron and was maintained for at least 3 months. These findings highlight the continued importance of booster vaccination regardless of history of prior COVID-19.<\/jats:p><\/jats:sec>","DOI":"10.1001\/jamanetworkopen.2022.46915","type":"journal-article","created":{"date-parts":[[2022,12,14]],"date-time":"2022-12-14T16:01:09Z","timestamp":1671033669000},"page":"e2246915","source":"Crossref","is-referenced-by-count":39,"title":["Estimated BNT162b2 Vaccine Effectiveness Against Infection With Delta and Omicron Variants Among US Children 5 to 11 Years of Age"],"prefix":"10.1001","volume":"5","author":[{"given":"Farid L.","family":"Khan","sequence":"first","affiliation":[{"name":"Medical Development & Scientific Clinical Affairs, Pfizer, Collegeville, Pennsylvania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jennifer L.","family":"Nguyen","sequence":"additional","affiliation":[{"name":"Medical Development & Scientific Clinical Affairs, Pfizer, Collegeville, Pennsylvania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tanya G.","family":"Singh","sequence":"additional","affiliation":[{"name":"Center for Health & Wellbeing Research, Walgreens, Deerfield, Illinois"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Laura A.","family":"Puzniak","sequence":"additional","affiliation":[{"name":"Medical Development & Scientific Clinical Affairs, Pfizer, Collegeville, Pennsylvania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Timothy L.","family":"Wiemken","sequence":"additional","affiliation":[{"name":"Medical Development & Scientific Clinical Affairs, Pfizer, Collegeville, Pennsylvania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Joshua P.","family":"Schrecker","sequence":"additional","affiliation":[{"name":"Clinical Affairs, Aegis Sciences Corporation, Nashville, Tennessee"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michael 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