Research carried out in Serrana (SP), a city in the interior of São Paulo, proved that mass vaccination reduced the rates of death and severe cases of the disease even during the circulation of the gamma and delta variants.
Scientists showed that the virus replacement dynamics in the city was similar to the rest of the country. It started with strains B.1.1.28 and B.1.1.33, for gamma, delta and omicron. In Serrana, the survey indicated that most cases for the 3 variants were mild – 88.9%, 98.1%, 99.1%, respectively. In the period, the vaccination rate in the city was 80%.
The researchers performed analyzes on 4,375 complete genomes in the period between June 2020 and April 2022 – the period between the initial introduction of SARS-CoV-2 until the vaccination process with at least two doses.
With monitoring, it was possible to detect the C.37 variant, which circulated intensely in Andean countries, but without significant dissemination in Brazil.
The study was published in the scientific journal Viruses“ and is part of Project S research carried out by the Butantan Institute with the support of FAPESP to monitor the effectiveness of vaccination in Serrana.
Of the 4,375 genomes analyzed in the research, 1,653 cases were identified with the delta variant (37.8%), 1,053 of gamma (24.1%), 1,513 of omicron (34.6%), 75 of zeta (1.7% ) and 81 referring to other lineages (1.9%). Although there were participants of all ages, the majority were between 21 and 50 years old.
The researchers claim that the application of the vaccine was related to the reduction of morbidity and mortality, especially during the gamma and delta waves. Compare with the city of São José do Rio Preto (SP), about 200 km from Serrana, where during the wave of the gamma variant there was a higher mortality rate among unvaccinated young people.
With information from FAPESP Agency.