The vaccine developed by Sinovac Biotech Ltd. was effective in controlling Covid-19 in a mass-inoculation study in a small Brazilian town after 75% of adults were covered with a second shot.
The study carried out by the Sao Paulo state government in the small town of Serrana -- population 45,000 -- may offer clues for other developing nations on how much of the public needs to be vaccinated in order to begin moving past the pandemic that continues to wreak havoc in Latin America and beyond.
The full results will be released during a press conference later on Monday with initial data broadcast on Sunday evening during TV Globo’s “Fantastico” program which interviewed researchers leading the project. While infection rates improved after first doses were administered, Covid-19 wasn’t properly controlled in the town until after a second shot was given, the researchers said.
The study was led by the Butantan Institute, which produces Sinovac’s so-called CoronaVac in Brazil. Almost two thirds of Serrana’s 45,000 inhabitants got the vaccine between February and April with another third ineligible to receive the shot if they were under 18 years old or pregnant. About 95% of the targeted adult population received the required two doses in the study.
While neighboring cities were being hit hard by the pandemic, Serrana saw deaths fall by 95% right after the mass-vaccination, symptomatic cases dropped by 80% and hospitalizations decreased by 86%, the report said. They didn’t say what time period was being used for the data.
Serrana mayor Leo Capitalize said in an interview that 40 days ago, 160-180 people were seeking a hospital bed on a daily basis and that test positivity rates were at 69%. Now, the number of people seeking attention in the hospital due to Covid is down to 30 to 35 people and positivity is down to 20%.
At the time the project was announced in February, Butantan researchers said the study aimed to show the effectiveness of CoronaVac to control cases, deaths and hospitalizations from Covid-19 in the real world, and if the shot is able to reduce transmission, not only symptomatic cases.
Sinovac’s vaccine is being used widely in the developing world including Chile, Turkey, Indonesia and the Philippines.
The findings also underline the importance of people returning for a second shot. In Brazil, some 66 million vaccines have been administered, covering 21.4% of the population with a single dose. About 10.5% of the country is now considered to be fully inoculated, according to the Bloomberg vaccine tracker.