One of the countries most severely affected by the coronavirus; a tropical city of more than 45,000 inhabitants; and a Chinese serum. These are the ingredients of ‘Project S’, an initiative to immunize an entire population whose results shed a very promising light on the possible end of the pandemic.
The experiment in question, carried out by the Butantan Institute, consisted of rapidly immunizing a large part of the population of the city of Serrana (in the state of Sao Paulo, Brazil), in order to be able to study the subsequent development of the pandemic. To this end, the city was divided into four areas with an equivalent population and the Chinese vaccine Coronavac, from the company Sinovac Pharma, was progressively applied to more than 95% of the adults living in them. At the same time, the main indicators of epidemiological evolution (number of confirmed infections, deaths, cumulative incidence) were monitored to find the immunization threshold capable of containing the virus.
The researchers found that this point was reached by fully vaccinating all adults in three of these areas, i.e. with 75% of all adults in the locality immunized. This resulted in a significant decrease in the indicators, which was also extended to unvaccinated adolescents and children.
This decrease became even more pronounced when 95% of the adults were fully immunized; with this figure, a 95% decrease in deaths, 86% in hospitalizations and 80% in symptomatic cases was achieved, according to the institute’s own data.
For the researchers, this demonstrates the usefulness of the vaccine not only as an individual protection measure, but also as a public health strategy. Epidemiological data were already beginning to decline in a promising way with 50% vaccination, and with 75% the pandemic could be considered controlled, with a significant decrease in unvaccinated groups and even in neighboring populations where a significant number of residents regularly travel to Serrana.
Furthermore, taking into account the remission of the pandemic among children and adolescents, the authors of the study concluded that it would not be necessary to vaccinate these population groups in order to safely reopen schools.
Another key point of the study is the use of Sinovac Pharma’s Coronavac vaccine. The serum is surrounded by a certain amount of controversy, since different studies have placed its efficacy at values as disparate as 50 (precisely, by Brazilian researchers) and 90%.
Unlike the versions better known in the West, such as AstraZeneca, Moderna, Pfizer or Janssen, the Sinovac serum is a traditional vaccine, consisting of dead viral particles which, when inoculated into the body, provoke an immune reaction without the need to expose the person to the risks of the virus.
Butantan’s researchers found that there were no deaths or hospitalizations among those who received the vaccine, and they also claim that it is effective against the P.1 variant, the so-called “Brazilian”.
As promising as these results are, they are an exception in the Brazilian environment. The country continues to grow in terms of infections and is currently the second in the world in terms of number of deaths (more than 460,000), behind the United States, and the third in terms of number of infections, behind only the United States and India.
In addition, the vaccination campaign in the country is progressing slowly due to supply and logistical problems. So much so that a commission has been set up in the Senate to investigate the management of the pandemic by President Jair Bolsonaro, who has spoken out on numerous occasions against pandemic restrictions and vaccines.