SAO PAULO — Serrana, a city in southeastern Brazilian state of Sao Paulo, has seen a 95 per cent drop in Covid-19 deaths after it concluded vaccination of almost all adults, TV Globo reported on Sunday.

With 45,000 inhabitants Serrana is a healthy oasis in Brazil, which has the world's second deadliest outbreak with more than 461,000 deaths so far and a very slow immunisation pace due to the lack of vaccines.

Serrana was the subject of a study by Instituto Butantan, which produces the Coronavac vaccine developed by China's Sinovac Biotech in Brazil.

When vaccination was starting, the city had an increase in Covid cases, but the spread of the virus was contained once 75 per cent of the population was immunised, scientists found.

Scientists divided the city in four areas to try to understand which was the threshold to contain the spread of the virus and found that it was controlled after three areas received the second dose.

The number of symptomatic cases fell 80 per cent, and hospitalizations 86 per cent. Covid deaths fell 95 per cent, according to data given by Butantan to TV Globo.

Serrana is surrounded by cities that are still dealing with a spike in Covid cases. Ribeirao Preto, 15 miles (24km) away from Serrana, is going through a lockdown to try to contain the spread of Covid-19.

A similar experiment is underway in another city in Sao Paulo, Brazil's richest state. The city of Botucatu expects to immunise most of its 148,000 inhabitants with the Astra Zeneca vaccine. REUTERS