SAO PAULO - An unprecedented experiment in the world, carried out in Brazil's small town of Serrana, in Sao Paulo State, has succeeded in reducing new deaths from COVID-19 by 95 percent and controlling the pandemic after 75 percent of the adult population received two doses of Chinese company Sinovac's CoronaVac vaccine, local authorities said.

"We have achieved exemplary large-scale epidemiological laboratory work to demonstrate how the effectiveness of the vaccine can save lives and control the pandemic," Dimas Covas, president of the Butantan Institute which produces CoronaVac locally, said when presenting the conclusions of the trial at a press conference held by the state government on Monday.

The institute, run by the government of the state of Sao Paulo, the most populated state in Brazil and also the one most affected by COVID-19, carried out the experiment in Serrana, called Project S, to achieve herd immunity with CoronaVac, the most widely applied vaccine to date in Brazil.

The mass vaccination in Serrana proceeded between February and April and coincided with Brazil's second wave of COVID-19 infections. The town vaccinated more than 27,000 residents aged over 18 with two doses of CoronaVac, about 60 percent of its population.

The result showed that deaths from COVID-19 were reduced by 95 percent, hospitalizations by 86 percent, and cases with symptoms by 80 percent.

At the press conference, Sao Paulo State Governor Joao Doria, accompanied by Covas and other scientists, announced that the study indicated that with 75 percent of the adult population immunized with both doses, the pandemic was brought under control.

"This same example can occur throughout Brazil with an increase in vaccination," said the governor.

According to Covas, the immunization of adults also protected children and adolescents who did not receive the vaccine from infection.

"An immunological belt was created," Covas said.

The study also indicated that all the variants of coronavirus could be fought by the vaccine, especially the one responsible for the second wave that caused the collapse of hospitals in Brazil between February and April -- the deadly P.1 variant that emerged in the Amazon.

Through vaccination, Serrana saved lives and protected its hospitals as all the surrounding cities saw their hospitals collapse and a record number of deaths in March and April, including Ribeirao Preto, the best-known city in the region, famed for its production of sugar and its derivatives.

"The vaccine is safe, effective and efficient, of the highest quality and contributed to preventing the advance of the disease. It protects the vaccinated and the minority that was not vaccinated by expressively reducing viral circulation," said Covas.

Some 600 people worked on Project S to achieve mass vaccination, under the supervision of the Butantan Institute and the University of Sao Paulo.

Presenting research graphs at the press conference, Ricardo Palacios, the director of clinical research at the Butantan Institute, said: "The most important result was understanding that we can control the pandemic without vaccinating the entire population. When 70 or 75 percent coverage was reached, the decline in the (infection) rate was perceived in the unvaccinated."

The experiment in Serrana "demonstrates the importance of collective solutions such as vaccination" to tackling the pandemic, said Palacios, who was in charge of the trial.