What we can learn from Brazil’s only fully-vaccinated city

Covid-19 vaccination in Brazil has been a calamitous process thus far. With the federal government casting doubt over the efficacy of immunizers for months, refusing offers from vaccine manufacturers, and even actively campaigning against the Chinese-made CoronaVac, immunization efforts have been set back significantly. Several variants of the coronavirus are spreading unchecked in the country, which has recorded over 365,000 deaths from Covid-19 so far. Dozens of thousands of new infections are recorded every day.

Amid this chaos, however, there is an oasis. In the small town of Serrana, some 300 kilometers north of Brazil’s biggest city São Paulo, the local administration concluded its adult mass vaccination program on Sunday. With the exception of children, pregnant women, and some vaccine risk groups, the entire town has now been vaccinated against Covid-19.

The town of just over 45,000 people was chosen to host the so-called Projeto S experiment, organized by the São Paulo-based Butantan Biological Institute, which will run until February 2022. The plan is to vaccinate a given community en masse and verify whether this has an effect on the virus’ spread. One possibility is that the vaccine merely reduces severe cases of Covid-19, yet does not stop infections.

According...