Brazil Turns Sleepy Sugarcane Town Into Global Covid-19 Experiment

SERRANA, Brazil—As Covid-19 has raged across Brazil, killing nearly a quarter of a million people, high infection rates have turned the country into the perfect testing ground for vaccines.

Now, Brazil is using its misfortune to help answer one of the pandemic’s most pressing questions as millions are being inoculated world-wide: Can someone who is vaccinated still transmit the virus?

In the first experiment of its kind globally, researchers Wednesday began a project to vaccinate the entire adult population of Serrana, a hard-hit commuter town of 45,000 people in São Paulo state, before the rest of the country.

By immunizing everyone in the town via controlled stages, they say the results will help the world’s scientists understand how quickly vaccines can curb the coronavirus pandemic. And inoculating an entire town will counter Brazil’s growing antivaccination movement and demonstrate the wider benefits of mass immunization, such as a quick economic recovery expected with a fast reopening of Serrana.

“It will give us information about the percentage of people who need to be vaccinated to reach herd immunity—no one knows this yet,” said Marcos Borges, a professor of medicine at the University of São Paulo in nearby Ribeirão Preto who is leading the study.