After vaccinating 95 percent of adults, a Brazilian city is returning to normal

In Serrana, Brazil, schools are reopening and plans are under way for a large open-air concert. Health care workers suddenly have time for sit-down meals rather than rushing to grab street food during a spare free moment. These scenes approaching normalcy stand in stark contrast to what’s happening across the rest of the country, where hospitals are jam-packed, businesses are largely closed and 2,000 people are dying each day from COVID-19.

Serrana, a city of 45,600 in the state of São Paulo, can begin to make these plans because an experiment called Projeto S, which vaccinated nearly all adults, appears to be drastically reducing COVID-19-related hospitalizations and deaths there.

Symptomatic cases have dropped 80 percent, with hospital admissions down 86 percent, down from a peak of around 600 cases per 100,000 people in early March, Projeto S leaders announced at a news conference on May 31. By two weeks after the second shot, only two fully vaccinated people landed in the hospital with COVID-19.

The incidence of COVID-19–related deaths per 100,000 inhabitants also dropped 95 percent in the city, the team leaders said, although the raw data behind the numbers has yet to be released. In April, the city recorded only six COVID-19 deaths, according to the Health Secretariat of Serrana. 

The project, in which over 95 percent of the city’s adults were given the Chinese-made CoronaVac vaccine, is a real-time experiment to measure the effectiveness the vaccine, including how well it protects against coronavirus variants (SN 5/5/21). In clinical trials, the CoronaVac vaccine had an efficacy of just over 50 percent, raising concerns of how well it would work in the real world.

“This project is important because it shows that even a vaccine with relatively low efficacy can have high efficiency and significantly decrease death rates in real-life settings,” says neuroscientist Mellanie Fontes-Dutra, coordinator of the COVID-19 Analysis Network in Brazil, who is not involved in the study.

The results also show the vaccine is effective against a more contagious version of the virus called P.1, which was dominant in Serrana by the time the study started, Ricardo Palácios, director for clinical trials at Instituto Butantan and director of Projeto S, said (SN: 4/14/21).

The numbers are still preliminary, and researchers will have to look at the raw data of the experiment to ensure the vaccine works on a large scale, Fontes-Dutra says. “But these preliminary numbers show we have an effective vaccine. And the most important thing to do is expand vaccination coverage as much as we can to have as many immunized people as possible.” 

As more people are vaccinated, they form a kind of immunological shield that protects individuals for whom the vaccine might not work so well or those who are still susceptible to infection, such as immunosuppressed HIV patients, Fontes-Dutra says.

The city is beginning to test the strength of that shield as residents return to church, families throw parties for their children and schools reopen. Cases have also dropped among those under 18, who are not yet vaccinated, suggesting the campaign is having a spillover protective effect, the researchers say.

On May 30, São Paulo governor João Doria announced on Fantástico, an evening TV show in Brazil, that there are even plans in the works for a “big open-air public event in Serrana, such as a music concert.” Along with offering some semblance of normalcy, the concert could be used to test the vaccine and its ability to protect people in large crowds, Doria said.

The event will provide important information to the Projeto S team, which will keep observing Serrana for a year to measure vaccine protection and how long it lasts.