D.he small Brazilian town of Serrana in the interior of the state of São Paulo will become the “laboratory” of the world’s first mass vaccination as part of a study. The state authorities announced this on Monday. The study envisages vaccinating as large a proportion of the adult population as possible in the small town with around 45,000 inhabitants in a short period of time.

The researchers estimate to vaccinate 30,000 citizens, with none of the residents required to participate in the mass vaccination. Pregnant women and nursing mothers as well as people who complained of fever shortly before the vaccination are also excluded. All participants will receive the first of two vaccinations in the next few weeks, and the second four weeks later. So far, a little more than 1,600 corona infections have been counted in Serrana, 52 resulting in death. In the past few weeks, the virus has spread faster in the small town. This fact and the size of the community were two key criteria for the selection.

How is the effectiveness “in the field”?

The study is being led by the butantane public institute in São Paulo, which has entered into a cooperation with the Chinese company Sinovac and which is currently also producing the Coronavac vaccine developed in China in its production facilities. The Butantan Institute was already heavily involved in the clinical tests of the vaccine. A large proportion of the Brazilians who have been vaccinated so far have received this vaccine. The aim of the study is to check the effectiveness of the vaccination in its widespread use. The study begins this Wednesday. The first solid results are expected in three months. Dimas Covas, director of the Butantan Institute, described the study as “another important step” that will provide further answers about vaccination. It is the first study of its kind in the world.

In the clinical tests in Brazil, the vaccine for Coronavac was found to be slightly more than 50 percent effective, which is rather low compared to other vaccines. In addition, the vaccination prevents the disease from getting serious in most cases. However, the researchers suspect that the effectiveness “in the field” and when the vaccination is used on a large scale is likely to deviate from this value, since the profile and behavior of the vaccinated differs from clinical tests. At the same time, the study aims to provide information on the effect of mass vaccinations on the spread of the virus.

The study is particularly important for Brazil, since Coronavac is currently the only vaccine that is available in large quantities and is produced in the country. A few days ago, Brazil also received the raw materials for the production of the vaccine from Astra-Zeneca. So far, almost four million people in Brazil have been vaccinated against the corona virus.