Effectiveness of CoronaVac in children 3–5 years of age during the SARS-CoV-2 Omicron outbreak in Chile

Journal
Nature Medicine
ISSN
1078-8956
Date Issued
2022
Author(s)
Alejandro Jara
Eduardo A. Undurraga
José R. Zubizarreta
Cecilia González
Acevedo, Johanna
Agencia Nacional de Investigación y Desarrollo, Gobierno de Chile Ministerio de Salud, Johns Hopkins University, Pontificia Universidad Catolica de Chile Escuela de Medicina, Pontificia Universidad Católica de Chile, Universidad de Los Andes, Chile, Universidad del Desarrollo
Alejandra Pizarro
Verónica Vergara
Mario Soto-Marchant
Rosario Gilabert
Juan Carlos Flores
Pamela Suárez
Paulina Leighton
Pablo Eguiguren
Juan Carlos Ríos
Jorge Fernandez
Heriberto García-Escorza
Type
Resource Types::text::journal::journal article
Scopus ID
2-s2.0-85131937439
WoS ID
WOS:000811448200001
DOI
URL
URL Institutional Repository
Abstract
<jats:title>Abstract</jats:title><jats:p>The outbreak of the B.1.1.529 lineage of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (Omicron) has caused an unprecedented number of Coronavirus Disease 2019 (COVID-19) cases, including pediatric hospital admissions. Policymakers urgently need evidence of vaccine effectiveness in children to balance the costs and benefits of vaccination campaigns, but, to date, the evidence is sparse. Leveraging a population-based cohort in Chile of 490,694 children aged 3–5 years, we estimated the effectiveness of administering a two-dose schedule, 28 days apart, of Sinovac’s inactivated SARS-CoV-2 vaccine (CoronaVac). We used inverse probability-weighted survival regression models to estimate hazard ratios of symptomatic COVID-19, hospitalization and admission to an intensive care unit (ICU) for children with complete immunization over non-vaccination, accounting for time-varying vaccination exposure and relevant confounders. The study was conducted between 6 December 2021 and 26 February 2022, during the Omicron outbreak in Chile. The estimated vaccine effectiveness was 38.2% (95% confidence interval (CI), 36.5–39.9) against symptomatic COVID-19, 64.6% (95% CI, 49.6–75.2) against hospitalization and 69.0% (95% CI, 18.6–88.2) against ICU admission. The effectiveness against symptomatic COVID-19 was modest; however, protection against severe disease was high. These results support vaccination of children aged 3–5 years to prevent severe illness and associated complications and highlight the importance of maintaining layered protections against SARS-CoV-2 infection.</jats:p>
Cite this document
Jara, A., Undurraga, E. A., Zubizarreta, J. R., González, C., Acevedo, J., Pizarro, A., Vergara, V., Soto-Marchant, M., Gilabert, R., Flores, J. C., Suárez, P., Leighton, P., Eguiguren, P., Ríos, J. C., Fernandez, J., García-Escorza, H., & Araos, R. (2022). Effectiveness of CoronaVac in children 3–5 years of age during the SARS-CoV-2 Omicron outbreak in Chile. Nature Medicine, 28(7), 1377-1380. https://doi.org/10.1038/s41591-022-01874-4
Dataset(s)
Subjects
models

; 

child

; 

child, preschool

; 

chile

; 

covid-19

; 

covid-19 vaccines

; 

disease outbreaks

; 

humans

; 

sars-cov-2

; 

viral vaccines

; 

coronavac

; 

virus vaccine

; 

article

; 

child

; 

child hospitalization

; 

chile

; 

cohort analysis

; 

controlled study

; 

coronavirus disease 2019

; 

drug efficacy

; 

female

; 

hospital admission

; 

human

; 

major clinical study

; 

male

; 

nonhuman

; 

sars-cov-2 omicron

; 

vaccination

; 

epidemic

; 

epidemiology

; 

preschool child