Three years of COVID-19 in children that attend the Mexican Social Security Institute's 1,350 child day-care centers, 2020-2023.

Background: Studies have suggested that children are less likely than adults to develop COVID-19; however, with the emergence of SARS-CoV-2 variants, hospitalization and death due to this cause have increased among the youngest ones.

Methods: Retrospective, descriptive analytical study of the COVID-19 cases, hospitalizations and deaths occurred in children under five years who attended in Child Day-Care Centers (CAIs of the Mexican Social Security Institute (IMSS) from 20th July 2020 to 31st March 2023. Results were compared with Mexico's and the US's national-level data.

Vaccine Effectiveness of CanSino (Adv5-nCoV) Coronavirus Disease 2019 (COVID-19) Vaccine Among Childcare Workers-Mexico, March-December 2021.

Background: Beginning in March 2021, Mexico vaccinated childcare workers with a single-dose CanSino Biologics (Adv5-nCoV) coronavirus disease 2019 (COVID-19) vaccine. Although CanSino is currently approved for use in 10 Latin American, Asian, and European countries, little information is available about its vaccine effectiveness (VE).

Methods: We evaluated CanSino VE within a childcare worker cohort that included 1408 childcare facilities.