Real-world Effectiveness of original BNT162b2 mRNA COVID-19 against symptomatic Omicron infection among Children 5-11 years of age in Brazil: a prospective test-negative design study.

To estimate original wild-type BNT162b2 effectiveness against symptomatic Omicron infection among children 5-11 years of age. This prospective test-negative, case-control study was conducted in Toledo, southern Brazil, from June 2022 to July 2023. Patients were included if they were aged 5-11 years, sought care for acute respiratory symptoms in the public health system, and were tested for SARS-CoV-2 using reverse transcription polymerase chain reaction. In the primary analysis, we determined the effectiveness of two doses of original wild-type BNT162b2 against symptomatic COVID-19. The reference exposure group was the unvaccinated. A total of 757 children were enrolled; of these, 461 (25 cases; 436 controls) were included in the primary analysis. Mean age was 7.4 years, 49.7% were female, 34.6% were obese, and 14.1% had chronic pulmonary disease. Omicron accounted for 100% of all identified SARS-CoV-2 variants with BA.5, BQ.1, and XBB.1 accounting for 35.7%, 21.4% and 21.4%, respectively. The adjusted estimate of two-dose vaccine effectiveness against symptomatic Omicron was 3.1% (95% CI, -133.7% to 61.8%) after a median time between the second dose and the beginning of COVID-19 symptoms of 192.5 days (interquartile range, 99 to 242 days). In this study with children 5-11 years of age, a two dose-schedule of original wild-type BNT162b2 was not associated with a significant protection against symptomatic Omicron infection after a median time between the second dose and the beginning of COVID-19 symptoms of 192 days, although the study may have been underpowered to detect a clinically important difference. ClinicalTrials.gov number, NCT05403307 (https://classic. gov/ct2/show/NCT05403307).

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Copyright © 2024. Published by Elsevier B.V.

Déclaration de conflit d'intérêts

Declaration of competing interest Rodrigues, Maltempi de Souza, Manfio, de Souza, Araujo, Cohen, Barbosa, Romeiro Silva, Sganzerla, Dias da Silva, Ferreira, Kunkel, Camargo, Sarturi, Guilhem, Oliveira, Lopes, Widmar, Barufi, Nunes da Silva, Gradia, Brandalize, Royer, Luiz, Baura, Abreu, and Poitevin report honoraria fee for working in this study from Hospital Moinhos de Vento. Rosa reports honoraria fee related to investigator activities from Pfizer, and research grants from Pfizer, MSD and Brazilian Ministry of Health. Falavigna reports honoraria fee related to investigator activities from Pfizer and MSD, consulting fees from Sanofi, Ultragenyx, Novartis, Alnylam, PTC and JCR, and honoraria for lectures from Janssen, Abbvie, Sanofi, Roche, Pfizer and Novartis.Valluri, Srivastava, Julião, Melone, Allen, Kyaw, Spinardi, Castillo, and McLaughlin are Pfizer empolyees. Kucharski, and Pedrotti have nothing to disclose.