Report of the Butantan Institute: Impact of mass vaccination in the municipality of Serrana (preliminary results not yet peer reviewed)

During the most recent four months of this year, researchers at the Butantan Institute measured the effects of large-scale immunization in the city of Serrana, in the interior of the state of São Paulo. The city, with 45,000 inhabitants, was chosen for mass vaccination because it had a high infection rate. In April 2021, once vaccinations had begun, Serrana already experienced a significant drop in the incidence of COVID-19. From 699 cases in March, the number of cases dropped to 251. In the same period, deaths went from 20 to 6. Results also showed that vaccination protected both adults who received the two doses of the vaccine and, by extension, unvaccinated children and adolescents under the age of 18.

According to the researchers, the pandemic was brought under control after three of four groups received the second dose, that is, about 75% of the population. According to the Butantan Institute, shortly after the vaccinations ended, the number of deaths in Serrana decreased by 95%, while the number of symptomatic cases of COVID-19 declined by 80%, and the number of hospitalizations dropped by approximately 86%. 

Source: https://butantan.gov.br/noticias/immunization-of-serrana%C2%B4s-population-with-butantan%C2%B4s-vaccine-has-a-high-decrease-of-80-cases-and-95-indeaths-by-covid-19