Person: Araos Bralic, Rafael Ignacio
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Araos Bralic
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Rafael Ignacio
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Publication Effectiveness of an inactivated SARS-CoV-2 vaccine in children and adolescents: a large-scale observational study(2023) Jara, Alejandro; Undurraga, Eduardo; Flores, Juan; Zubizarreta, José; González, Cecilia; Pizarro, Alejandra; Ortuño, Duniel; Acevedo, Johanna; Leo, Katherinne; Paredes, Fabio; Bralic , Tomás; Vergara, Verónica; Leon, Francisco; Parot, Ignacio; Leighton, Paulina; Suárez, Pamela; Rios, Juan; García, Heriberto; Rafael Araos; Araos Bralic, Rafael IgnacioBackground: 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)Publication Effectiveness of the second COVID-19 booster against Omicron: a large-scale cohort study in Chile(2023) Jara, Alejandro; Cuadrado, Cristobal; Undurraga, Eduardo; García , Christian; Nájera, Manuel; Bertoglia, María; Vergara, Verónica; Fernández , Jorge; García, Heriberto; Araos Bralic, Rafael IgnacioIn 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. A la luz de la actual pandemia de COVID-19 y la aparición de nuevas variantes del SARS-CoV-2, es fundamental comprender la eficacia de varios regímenes de vacunación de refuerzo. En Chile, utilizando una cohorte nacional prospectiva de 3,75 millones de personas de 20 años o más, evaluamos la efectividad contra las admisiones a unidades de cuidados intensivos (UCI) relacionadas con COVID-19 y la muerte de segundas dosis de refuerzo basadas en ARNm para cuatro dosis diferentes de tres dosis. regímenes: serie primaria BNT162b2 seguida de un refuerzo homólogo, y serie primaria CoronaVac seguida de un refuerzo de ARNm, un refuerzo homólogo y un refuerzo de ChAdOx-1. Estimamos la efectividad de la vacuna semanalmente del 14 de febrero al 15 de agosto de 2022, determinando los índices de riesgo de inmunización frente a no vacunación, teniendo en cuenta los factores de confusión relevantes. La eficacia global ajustada de una segunda inyección de refuerzo de ARNm es del 88,2% (IC del 95%, 86,2-89,9) frente a los ingresos en la UCI y del 90,5% (IC del 95%, 89,4-91,4) frente a la muerte. La eficacia de la vacuna muestra una leve disminución en todos los regímenes y resultados, probablemente relacionada con la introducción de los sublinajes Omicron BA.4 y BA.5 y la disminución de la inmunidad. Según nuestros hallazgos, es posible que las personas no necesiten refuerzos adicionales durante al menos 6 meses después de recibir una segunda inyección de refuerzo de ARNm en este entorno.