The small Brazilian town of Serrana has carried out an experiment called "Project S" to achieve herd immunity by vaccinating its entire adult population with China's CoronaVac vaccine and verify the vaccine's effectiveness against COVID-19.
The project was led by Sao Paulo-based Butantan Institute, a state government-funded scientific research center that produces CoronaVac vaccine locally.
The result of the trial was released Monday at a press conference at the institute.
It shows that comparing the data from the beginning of the project in February until the vaccination of all groups was completed in April, the symptomatic cases dropped by 80 percent, the hospitalization fell by 86 percent, and the death cases decreased by 95 percent.
Serrana has more than 45,000 residents.
Excluding children, pregnant women, about 27,000 people have received vaccination between February and April.
The study also indicated that other variants of coronavirus could be fought by the vaccine, especially the P1 or the Amazon variant that was responsible for the second wave of the pandemic in the country.
The clinical study is considered pioneering worldwide in determining the herd immunity of the vaccine.
Produced by Xinhua Global Service
