Este articulo es un Preprint
Los preprints son informes de investigación preliminares que no han sido certificados por revisión por pares. No deben considerarse para guiar la práctica clínica o los comportamientos relacionados con la salud y no deben publicarse en los medios como información establecida.
Los preprints publicados en línea permiten a los autores recibir comentarios rápidamente, y toda la comunidad científica puede evaluar de forma independiente el trabajo y responder adecuadamente. Estos comentarios se publican junto con los preprints para que cualquiera pueda leer y servir como una revisión pospublicación.
Effectiveness and Duration of Protection of a Fourth Dose of COVID-19 mRNA Vaccine among Long-Term Care Residents in Ontario, Canada
Preprint
en En
| PREPRINT-MEDRXIV
| ID: ppmedrxiv-22280526
ABSTRACT
BackgroundAs of December 30, 2021, Ontario long-term care (LTC) residents who received a third dose of COVID-19 vaccine [≥]84 days previously were offered a fourth dose to prevent a surge in COVID-19-related morbidity and mortality due to the Omicron variant. Seven months have passed since fourth doses were implemented, allowing for the examination of fourth dose protection over time. MethodsWe used a test-negative design and linked databases to estimate the marginal effectiveness (4 versus 3 doses) and vaccine effectiveness (VE; 2, 3, or 4 doses versus no doses) of mRNA vaccines among Ontario LTC residents aged [≥]60 years who were tested for SARS-CoV-2 between December 30, 2021 and August 3, 2022. Outcome measures included any Omicron infection, symptomatic infection, and severe outcomes (hospitalization or death). ResultsWe included 21,275 Omicron cases and 273,466 test-negative controls. The marginal effectiveness of a fourth dose <84 days ago compared to a third dose received [≥]84 days ago was 23% (95% Confidence Interval [CI] 17-29%), 36% (95%CI 26-44%), and 37% (95%CI 24-48%) against SARS-CoV-2 infection, symptomatic infection, and severe outcomes, respectively. Additional protection provided by a fourth dose compared to a third dose was negligible against all outcomes [≥]168 days after vaccination. Compared to unvaccinated individuals, vaccine effectiveness (VE) of a fourth dose decreased from 49% (95%CI 44%-54%) to 18% (95%CI 5-28%) against infection, 69% (95%CI 62-75%) to 44% (95%CI 24-59%) against symptomatic infection, and 82% (95%CI 77-86%) to 74% (95%CI 62-82%) against severe outcomes <84 days versus [≥]168 days after vaccination. ConclusionsOur findings suggest that fourth doses of mRNA COVID-19 vaccines provide additional protection against Omicron-related outcomes in LTC residents, but the protection wanes over time, with more waning seen against infection than severe outcomes.
cc_by_nc_nd
Texto completo:
1
Colección:
09-preprints
Base de datos:
PREPRINT-MEDRXIV
Tipo de estudio:
Experimental_studies
/
Observational_studies
/
Prognostic_studies
Idioma:
En
Año:
2022
Tipo del documento:
Preprint