• Flor M Muñoz, Lawrence D Sher, Charu Sabharwal, Alejandra Gurtman, Xia Xu, Nicholas Kitchin, Stephen Lockhart, Robert Riesenberg, Joanna M Sexter, Hanna Czajka, Grant C Paulsen, Yvonne Maldonado, Emmanuel B Walter, Kawsar R Talaat, Janet A Englund, Uzma N Sarwar, Caitlin Hansen, Martha Iwamoto, Chris Webber, Luke Cunliffe, Benita Ukkonen, Silvina N Martínez, Barbara A Pahud, Iona Munjal, Joseph B Domachowske, Kena A Swanson, Hua Ma, Kenneth Koury, Susan Mather, Claire Lu, Jing Zou, Xuping Xie, Pei-Yong Shi, David Cooper, Özlem Türeci, Uğur Şahin, Kathrin U Jansen, William C Gruber, and C4591007 Clinical Trial Group.
• From Texas Children's Hospital, Baylor College of Medicine, Houston (F.M.M.), and the University of Texas Medical Branch, Galveston (J.Z., X. Xie, P.-Y.S.); Peninsula Research Associates, Rolling Hills Estates (L.D.S.), and Stanford University School of Medicine, Palo Alto (Y.M.) - both in California; Vaccine Research and Development, Pfizer, Pearl River (C.S., A.G., U.N.S., C.H., M.I., B.A.P., I.M., K.A.S., K.K., C.L., D.C., K.U.J., W.C.G.), and SUNY Upstate Medical University, Syracuse (J.B.D.) - both in New York; Vaccine Research and Development (X. Xu, H.M.), and Worldwide Safety, Safety Surveillance and Risk Management (S.M.), Pfizer, Collegeville, PA; Vaccine Research and Development, Pfizer, Hurley, United Kingdom (N.K., S.L., C.W., L.C.); Atlanta Center for Medical Research, Atlanta (R.R.); Spring Valley Pediatrics, Washington, DC (J.M.S.); Katedra Pediatrii, Instytut Nauk Medycznych, Kolegium Nauk Medycznych, Uniwersytet Rzeszowski, Rzeszow, Poland (H.C.); the Department of Pediatrics, University of Cincinnati College of Medicine, and the Division of Pediatric Infectious Diseases, Cincinnati Children's Hospital Medical Center, Cincinnati (G.C.P.); Duke Human Vaccine Institute, Durham, NC (E.B.W.); Johns Hopkins University, Baltimore (K.R.T.); Seattle Children's Hospital, Seattle (J.A.E.); Tampere University, Espoo Vaccine Research Clinic, Espoo, Finland (B.U.); Hospital Universitario HM Puerta del Sur, Madrid (S.N.M.); and BioNTech, Mainz, Germany (Ö.T., U.Ş.).
• N. Engl. J. Med. 2023 Feb 16; 388 (7): 621634621-634.

BackgroundSafe and effective vaccines against coronavirus disease 2019 (Covid-19) are urgently needed in young children.MethodsWe conducted a phase 1 dose-finding study and are conducting an ongoing phase 2-3 safety, immunogenicity, and efficacy trial of the BNT162b2 vaccine in healthy children 6 months to 11 years of age. We present results for children 6 months to less than 2 years of age and those 2 to 4 years of age through the data-cutoff dates (April 29, 2022, for safety and immunogenicity and June 17, 2022, for efficacy). In the phase 2-3 trial, participants were randomly assigned (in a 2:1 ratio) to receive two 3-μg doses of BNT162b2 or placebo. On the basis of preliminary immunogenicity results, a third 3-μg dose (≥8 weeks after dose 2) was administered starting in January 2022, which coincided with the emergence of the B.1.1.529 (omicron) variant. Immune responses at 1 month after doses 2 and 3 in children 6 months to less than 2 years of age and those 2 to 4 years of age were immunologically bridged to responses after dose 2 in persons 16 to 25 years of age who received 30 μg of BNT162b2 in the pivotal trial.ResultsDuring the phase 1 dose-finding study, two doses of BNT162b2 were administered 21 days apart to 16 children 6 months to less than 2 years of age (3-μg dose) and 48 children 2 to 4 years of age (3-μg or 10-μg dose). The 3-μg dose level was selected for the phase 2-3 trial; 1178 children 6 months to less than 2 years of age and 1835 children 2 to 4 years of age received BNT162b2, and 598 and 915, respectively, received placebo. Immunobridging success criteria for the geometric mean ratio and seroresponse at 1 month after dose 3 were met in both age groups. BNT162b2 reactogenicity events were mostly mild to moderate, with no grade 4 events. Low, similar incidences of fever were reported after receipt of BNT162b2 (7% among children 6 months to <2 years of age and 5% among those 2 to 4 years of age) and placebo (6 to 7% among children 6 months to <2 years of age and 4 to 5% among those 2 to 4 years of age). The observed overall vaccine efficacy against symptomatic Covid-19 in children 6 months to 4 years of age was 73.2% (95% confidence interval, 43.8 to 87.6) from 7 days after dose 3 (on the basis of 34 cases).ConclusionsA three-dose primary series of 3-μg BNT162b2 was safe, immunogenic, and efficacious in children 6 months to 4 years of age. (Funded by BioNTech and Pfizer; ClinicalTrials.gov number, NCT04816643.).Copyright © 2023 Massachusetts Medical Society.

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