The study will be carried out among those above the age of 12 in the town of Toledo, west of the country’s Parana state, according to the company.
“The initiative is the first and only of its kind to be undertaken in collaboration with the pharmaceutical company in a developing country,” Pfizer said on Wednesday.
The observational study will help researchers find out the “real-life scenario” of the transmission of the coronavirus once an entire population is vaccinated.
It will aim to validate the real-world efficacy and safety of the Pfizer vaccine seen in clinical trials, Regis Goulart, a researcher at Porto Alegre’s Moinhos de Vento hospital, told Reuters.
Participants will be monitored for a year and will help answer questions such as the emergence of new variants and how long vaccines will prove to protect against Covid-19, Mr Goulart added.
The study will be done in partnership with Brazil’s national vaccination programme, local health authorities, a federal university and the Moinhos de Vento hospital.
Toledo, where the study will take place, has a population of 143,000 and little to account for in terms of vaccine hesitancy.
At least 98 per cent of its population has already received a first dose of a vaccine, primarily Pfizer, reported Reuters.
Around 56 per cent of the town is also fully vaccinated, with AstraZeneca and Sinovac vaccines being used as well, said municipal health secretary Gabriela Kucharski.
“Here we believe in science and we lament the almost 600,000 deaths from COVID-19 in Brazil,” Beto Lunitti, the town’s mayor, said at a press conference announcing the Pfizer study.
Butantan Institute, a leading biomedical research centre in Brazil which conducted the study, said in May that mass vaccination reduced Covid-19 deaths by 95 per cent in the town, which has a population of 45,644 people.
The institute is considering extending the study for a third dose, according to Reuters.
Additional reporting by agencies