A study carried out by the Butantan Institute and recently published in science magazine Viruses demonstrated that mass vaccination carried out in the city of Serrana in São Paulo reduced severe cases and deaths caused by covid-19.
The survey – carried out in partnership with the Blood Center of Ribeirão Preto and the State Hospital of Serrana and with support from the São Paulo Research Foundation (FAPESP) – pointed out that 95% of the cases of covid-19 identified in Serrana were mild, even when caused by the Omicron or Delta variants, which spread more quickly.
For this study, researchers sequenced 4,375 samples from people who tested positive for covid-19 between June 2020 and April 2022. Of this total, 1,653 cases were related to infection by the Delta variant, 1,053 by Gamma, 1,513 by Omicron and 156 by other lineages.
mass vaccination
The analysis also pointed out that mass vaccination caused 88.9% of the cases referring to the Gamma variant to be mild. In addition, 98.1% of occurrences related to the Delta variant and 99.1% related to Omicron were also mild.
According to the researchers, the study, despite not being focused on vaccine effectiveness, but on a phylogenetic analysis – which examines the evolutionary development of the virus – demonstrated the positive influence of vaccination.
“Despite the epidemic waves during the study period, we observed that vaccination was instrumental in reducing morbidity, severe cases and mortality,” they said.
The result of the research confirmed a previous study released by Projeto S, which pointed to an effectiveness of 80.5% of CoronaVac against symptomatic cases of covid-19, 95% against hospitalizations and 94.9% against deaths caused by covid-19.
sublineages
The study also identified 52 strains of the Sars-CoV-2 virus circulating in the city of Serrana, including rare variants that had not been described in the rest of the country.
“This shows the relevance of a systemic monitoring of circulating strains, which provides important molecular and epidemiological information, helping not only to monitor rare lineages, but also to predict the introduction of worrying variants and predict future epidemic waves”, revealed the article. .
Serrana was part of a clinical study that evaluated the efficiency and effectiveness of the CoronaVac vaccine, a vaccine produced by the Butantan Institute and the Chinese laboratory Sinovac. Called Project S, this survey began in February last year, with mass vaccination of the entire adult population of Serrana with CoronaVac??
