Effectiveness of the second COVID-19 booster against Omicron: a large-scale cohort study in Chile
Journal
Nature Communications
ISSN
2041-1723
Date Issued
2023
Author(s)
Alejandro Jara
Cristobal Cuadrado
Eduardo A. Undurraga
Christian García
Manuel Nájera
María Paz Bertoglia
Verónica Vergara
Jorge Fernández
Heriberto García-Escorza
Type
Resource Types::text::journal::journal article
URL Institutional Repository
Abstract
<jats:title>Abstract</jats:title><jats:p>In light of the ongoing COVID-19 pandemic and the emergence of new SARS-CoV-2 variants, understanding the effectiveness of various booster vaccination regimens is pivotal. In Chile, using a prospective national cohort of 3.75 million individuals aged 20 or older, we evaluate the effectiveness against COVID-19-related intensive care unit (ICU) admissions and death of mRNA-based second vaccine boosters for four different three-dose background regimes: BNT162b2 primary series followed by a homologous booster, and CoronaVac primary series followed by an mRNA booster, a homologous booster, and a ChAdOx-1 booster. We estimate the vaccine effectiveness weekly from February 14 to August 15, 2022, by determining hazard ratios of immunization over non-vaccination, accounting for relevant confounders. The overall adjusted effectiveness of a second mRNA booster shot is 88.2% (95%CI, 86.2–89.9) against ICU admissions and 90.5% (95%CI 89.4–91.4) against death. Vaccine effectiveness shows a mild decrease for all regimens and outcomes, probably linked to the introduction of BA.4 and BA.5 Omicron sub-lineages and the waning of immunity. Based on our findings, individuals might not need additional boosters for at least 6 months after receiving a second mRNA booster shot in this setting.</jats:p>
Cite this document
Jara, A., Cuadrado, C., Undurraga, E. A., García, C., Nájera, M., Bertoglia, M. P., Vergara, V., Fernández, J., García-Escorza, H., & Araos, R. (2023). Effectiveness of the second COVID-19 booster against Omicron: A large-scale cohort study in Chile. Nature Communications, 14(1), 6836. https://doi.org/10.1038/s41467-023-41942-y
Subjects
bnt162 vaccine
;
chile
;
cohort studies
;
covid-19
;
humans
;
pandemics
;
prospective studies
;
rna, messenger
;
sars-cov-2
;
sars-cov-2 variants
;
chile
;
coronavac
;
tozinameran
;
vaxzevria
;
bnt 162 vaccine
;
coronavac
;
messenger rna
;
covid-19
;
immunization
;
rna
;
vaccination
;
vaccine
;
adult
;
article
;
chile
;
cohort analysis
;
confounding variable
;
controlled study
;
coronavirus disease 2019
;
drug efficacy
;
female
;
hospital admission
;
human
;
immunization
;
intensive care unit
;
major clinical study
;
male
;
prospective study
;
sars-cov-2 omicron
;
coronavirus disease 2019
;
pandemic
;
severe acute respiratory syndrome coronavirus 2