Effectiveness of the BNT162b2 vaccine among children 5-11 and 12-17 years in New York after the Emergence of the Omicron Variant

Abstract

Importance: There is limited evidence on the effectiveness of the BNT162b2 vaccine for children, particularly those 5-11 years and after the Omicron variant's emergence. Objective: To estimate BNT162b2 vaccine effectiveness against COVID cases and hospitalizations among children 5-11 years and 12-17 years during December, 2021 and January, 2022. Design: Analyses of cohorts constructed from linked statewide immunization, laboratory testing, and hospitalization databases. Setting/Participants: New York State children 5-17 years. Main outcomes/measures: New laboratory-confirmed COVID-19 cases and hospitalizations. Comparisons were made using the incidence rate ratio (IRR), comparing outcomes by vaccination status, and estimated vaccine effectiveness (VE: 1-[1/IRR]). Results: From December 13, 2021 to January 30, 2022, among 852,384 fully-vaccinated children 12-17 years and 365,502 children 5-11 years, VE against cases declined from 66% (95% CI: 64%, 67%) to 51% (95% CI: 48%, 54%) for those 12-17 years and from 68% (95% CI: 63%, 72%) to 12% (95% CI: 6%, 16%) for those 5-11 years. During the January 24-30 week, VE for children 11 years was 11% (95%CI -3%, 23%) and for those age 12 was 67% (95% CI: 62%, 71%). VE against hospitalization declined changed from 85% (95% CI: 63%, 95%) to 73% (95% CI: 53%, 87%) for children 12-17 years, and from 100% (95% CI: -189%, 100%) to 48% (95% CI: -12%, 75%) for those 5-11 years. Among children newly fully-vaccinated December 13, 2021 to January 2, 2022, VE against cases within two weeks of full vaccination for children 12-17 years was 76% (95% CI: 71%, 81%) and by 28-34 days it was 56% (95% CI: 43%, 63%). For children 5-11, VE against cases declined from 65% (95% CI: 62%, 68%) to 12% (95% CI: 8%, 16%) by 28-34 days. Conclusions and Relevance: In the Omicron era, the effectiveness against cases of BNT162b2 declined rapidly for children, particularly those 5-11 years. However, vaccination of children 5-11 years was protective against severe disease and is recommended. These results highlight the potential need to study alternative vaccine dosing for children and the continued importance layered protections, including mask wearing, to prevent infection and transmission.

Effectiveness of CoronaVac in children 3 to 5 years during the omicron SARS-CoV-2 outbreak

“…Recent research suggests that vaccines may be less effective against omicron. Consistent with our results, an unpublished study in New York, 13 found that the vaccine effectiveness of BNT162b2 for the prevention of Covid-19 and hospitalization decreased from 66-51% and from 85-73% for children aged 12-17 years, respectively. The drop was more considerable among children 5 to 11 years; protection against Covid-19 fell from 68-12%, and protection against hospitalization fell from 100-48%.…”

“…The drop was more considerable among children 5 to 11 years; protection against Covid-19 fell from 68-12%, and protection against hospitalization fell from 100-48%. 13 Results among adults tell the same story. Early data from South Africa reported that BNT162b2 protection against Covid-19 related hospitalization decreased from 93-70% among adults.…”

“…10 Evidence of the e cacy or effectiveness of Covid-19 vaccines in children is limited, primarily related to mRNA vaccines, and only one study was conducted during the omicron outbreak. [11][12][13][14] To the best of our knowledge, there is no evidence of vaccine effectiveness against Covid-19 in children under ve years. Furthermore, recent research suggests that several Covid-19 vaccine platforms provide limited protection against infection and symptomatic disease caused by the omicron variant but were more effective against severe disease.…”

“…populations but are consistent with preliminary, unpublished results from a study in children 5 to 12 years. 13 Leveraging a population-based cohort of children aged 3 to 5 years, we estimated the effectiveness of the complete primary immunization schedule (two doses, 28 days apart) of an inactivated SARS-CoV-2 vaccine, CoronaVac, to prevent laboratory-con rmed Covid-19, hospitalization, and admission to an intensive care unit (ICU). We estimated vaccine effectiveness using inverse probability-weighted survival regression models to estimate hazard ratios of complete immunization (starting 14 days after the second dose) over the unvaccinated status, accounting for time-varying vaccination exposure and available clinical, demographic, and socioeconomic confounders at baseline.…”

“…16 Similarly, a study that evaluated serum neutralization against omicron or D614G variant among adult participants with the mRNA-1273 vaccine primary series observed neutralization titers 35 times lower for omicron. 17 Children's age could also potentially affect vaccine effectiveness estimates for severe disease, as suggested by older children in recent unpublished studies in New York 13 and Chile. 14 Observational studies have limitations.…”