TY - JOUR
T1 - Effectiveness of an inactivated SARS-CoV-2 vaccine in children and adolescents
T2 - a large-scale observational study
AU - Jara, Alejandro
AU - Undurraga, Eduardo A.
AU - Flores, Juan Carlos
AU - Zubizarreta, José R.
AU - González, Cecilia
AU - Pizarro, Alejandra
AU - Ortuño-Borroto, Duniel
AU - Acevedo, Johanna
AU - Leo, Katherinne
AU - Paredes, Fabio
AU - Bralic, Tomás
AU - Vergara, Verónica
AU - Leon, Francisco
AU - Parot, Ignacio
AU - Leighton, Paulina
AU - Suárez, Pamela
AU - Rios, Juan Carlos
AU - García-Escorza, Heriberto
AU - Araos, Rafael
N1 - Publisher Copyright:
© 2023
PY - 2023/5
Y1 - 2023/5
N2 - Background: Policymakers urgently need evidence to adequately balance the costs and benefits of mass vaccination against COVID-19 across all age groups, including children and adolescents. In this study, we aim to assess the effectiveness of CoronaVac's primary series among children and adolescents in Chile. Methods: We used a large prospective national cohort of about two million children and adolescents 6–16 years to estimate the effectiveness of an inactivated SARS-CoV-2 vaccine (CoronaVac) in preventing laboratory-confirmed symptomatic SARS-CoV-2 infection (COVID-19), hospitalisation, and admission to an intensive care unit (ICU) associated with COVID-19. We compared the risk of individuals treated with a complete primary immunization schedule (two doses, 28 days apart) with the risk of unvaccinated individuals during the follow-up period. The study was conducted in Chile from June 27, 2021, to January 12, 2022, when the SARS-CoV-2 Delta variant was predominant but other variants of concern were co-circulating, including Omicron. We used inverse probability-weighted survival regression models to estimate hazard ratios of complete immunization over the unvaccinated status, accounting for time-varying vaccination exposure and adjusting for relevant demographic, socioeconomic, and clinical confounders. Findings: The estimated adjusted vaccine effectiveness for the inactivated SARS-CoV-2 vaccine in children aged 6–16 years was 74.5% (95% CI, 73.8–75.2), 91.0% (95% CI, 87.8–93.4), 93.8% (95% CI, 87.8–93.4) for the prevention of COVID-19, hospitalisation, and ICU admission, respectively. For the subgroup of children 6–11 years, the vaccine effectiveness was 75.8% (95% CI, 74.7–76.8) for the prevention of COVID-19 and 77.9% (95% CI, 61.5–87.3) for the prevention of hospitalisation. Interpretation: Our results suggest that a complete primary immunization schedule with the inactivated SARS-CoV-2 vaccine provides effective protection against severe COVID-19 disease for children 6–16 years. Funding: Agencia Nacional de Investigación y Desarrollo (ANID) Millennium Science Initiative Program and Fondo de Financiamiento de Centros de Investigación en Áreas Prioritarias (FONDAP).
AB - Background: Policymakers urgently need evidence to adequately balance the costs and benefits of mass vaccination against COVID-19 across all age groups, including children and adolescents. In this study, we aim to assess the effectiveness of CoronaVac's primary series among children and adolescents in Chile. Methods: We used a large prospective national cohort of about two million children and adolescents 6–16 years to estimate the effectiveness of an inactivated SARS-CoV-2 vaccine (CoronaVac) in preventing laboratory-confirmed symptomatic SARS-CoV-2 infection (COVID-19), hospitalisation, and admission to an intensive care unit (ICU) associated with COVID-19. We compared the risk of individuals treated with a complete primary immunization schedule (two doses, 28 days apart) with the risk of unvaccinated individuals during the follow-up period. The study was conducted in Chile from June 27, 2021, to January 12, 2022, when the SARS-CoV-2 Delta variant was predominant but other variants of concern were co-circulating, including Omicron. We used inverse probability-weighted survival regression models to estimate hazard ratios of complete immunization over the unvaccinated status, accounting for time-varying vaccination exposure and adjusting for relevant demographic, socioeconomic, and clinical confounders. Findings: The estimated adjusted vaccine effectiveness for the inactivated SARS-CoV-2 vaccine in children aged 6–16 years was 74.5% (95% CI, 73.8–75.2), 91.0% (95% CI, 87.8–93.4), 93.8% (95% CI, 87.8–93.4) for the prevention of COVID-19, hospitalisation, and ICU admission, respectively. For the subgroup of children 6–11 years, the vaccine effectiveness was 75.8% (95% CI, 74.7–76.8) for the prevention of COVID-19 and 77.9% (95% CI, 61.5–87.3) for the prevention of hospitalisation. Interpretation: Our results suggest that a complete primary immunization schedule with the inactivated SARS-CoV-2 vaccine provides effective protection against severe COVID-19 disease for children 6–16 years. Funding: Agencia Nacional de Investigación y Desarrollo (ANID) Millennium Science Initiative Program and Fondo de Financiamiento de Centros de Investigación en Áreas Prioritarias (FONDAP).
KW - COVID-19
KW - Inactivated SARS-CoV-2 vaccine
KW - mRNA vaccine
KW - Paediatric cohort
KW - SARS-CoV-2
KW - Vaccine effectiveness
UR - http://www.scopus.com/inward/record.url?scp=85152930064&partnerID=8YFLogxK
U2 - 10.1016/j.lana.2023.100487
DO - 10.1016/j.lana.2023.100487
M3 - Article
AN - SCOPUS:85152930064
SN - 2667-193X
VL - 21
JO - The Lancet Regional Health - Americas
JF - The Lancet Regional Health - Americas
M1 - 100487
ER -
