Effectiveness of BNT162b2 Vaccine against Omicron in Children 5 to 11 Years

Abstract

Background
Since it was first identified in early November 2021, the coronavirus disease 2019 (Covid-19) B.1.1.529 (omicron) variant has spread quickly and replaced the B.1.617.2 (delta) variant as the dominant variant in many countries. Data on the real-world effectiveness of vaccines against the omicron variant for children is currently lacking.

Methods
We performed a study of 255,773 children between 5 to 11 years old in Singapore during the period from January 21 to February 24, 2022 when the omicron variant was rapidly spreading. Outcomes included the rates of all reported SARS-CoV-2 infections, polymerase chain reaction-confirmed infections, as well as hospitalizations among unvaccinated, partially vaccinated and fully vaccinated groups. The incidence rate ratio (IRR) of outcomes between different groups was obtained using a Poisson regression, including sex, race, age, housing type, and date of study as covariates.

Results
Among unvaccinated individuals, the incidences of all infections, PCR-confirmed infections and hospitalizations were 2744, 559, and 28 per million person-days. Compared with unvaccinated children, the adjusted IRRs for all infections, PCR-confirmed infections and hospitalizations for partially vaccinated children were 0.86 (95% CI, 0.84 to 0.89), 0.78 (95% CI, 0.72 to 0.83) and 0.66 (95% CI, 0.47 to 0.93) respectively. For fully vaccinated individuals, the IRRs were 0.57 (95% CI, 0.55 to 0.59), 0.36 (95% CI, 0.32 to 0.42), and 0.13 (95% CI, 0.04 to 0.36) respectively.

Conclusions
The BNT162b2 vaccine is associated with lower Covid-19 hospitalizations among children, and may aid in preventing pediatric healthcare systems from being overwhelmed during the omicron wave.

Note:
Funding Information: None to declare.

Conflict of Interests: None to declare.

Ethical Approval: Data collection and analysis for this study was carried out under the Infectious Disease Act to support policy decision-making and evaluation, and was exempted from ethics review.

Keywords: COVID-19, SARS-CoV-2, Vaccination, mRNA Vaccine, Child