98.9% of paulistanos had Covid or were immunized, says study

Practically the entire population of the city of São Paulo, or 98.9%, has specific antibodies in the blood against the Sars-CoV-2 coronavirus, which indicates either a previous infection with the virus or an immune response generated after vaccination against Covid.

The numbers are from the eighth and final stage of the serological mapping of the capital of São Paulo carried out by the Fleury laboratory in partnership with Ipec (Intelligence in Research and Consulting, formerly Ibope), Instituto Semeia and Todos pela Saúde.

According to the survey, the share of the population likely to become infected with the virus grew in 2022 compared to the end of last year, from approximately 52.8% in September to 79.1% in April 2022.

The number of people from São Paulo who have antibodies generated after receiving at least two doses of Covid vaccines went from 81.8% in 2021 to 96.3% in the last month.

​In the same period, 8 out of 10 people in São Paulo (83.1%) had specific antibodies against the omicron variant of the coronavirus, indicating that practically a third of new infections occurred during the period of the omicron wave.

The serological study in individuals over 18 years of age in São Paulo uses two different tests to assess the presence in the blood of specific antibodies to the coronavirus.

One of them looks for antibodies produced against the nucleoprotein (protein present in the nucleus) of Sars-CoV-2, which may indicate either a previous infection or immunization with Coronavac.

The other test looks for neutralizing antibodies, capable of blocking the entry of the virus into cells. These antibodies are generated after vaccination with the other immunizers.

In terms of income, the new phase of the project corroborated what had already been observed in the others: that the poorest districts of the city were more affected by the natural infection of the virus compared to the richest. In the half of the city that comprises the districts with the lowest average income, 84.7% of respondents had antibodies against the nucleoprotein, against 72.9% in those living in the higher-income districts.

There was no significant difference in the prevalence of neutralizing antibodies between the two poorest and richest regions of the city, indicating that vaccination had an equal distribution in the population.

The survey was carried out between March 31 and April 9, 2022, when the city had already recorded a total of 1,917,503 cases and more than 42,000 deaths from Covid, since the beginning of the pandemic.

In São Paulo, the adult population is 9,267,688 inhabitants. Thus, the survey indicates that at least 9.16 million have already been infected or vaccinated against the coronavirus. Thus, the approximately 1.9 million confirmed cases are equivalent to about a fifth (22%) of the total adult population.

According to the biologist and professor at USP (University of São Paulo) and the main coordinator of the study, Fernando Reinach, when looking only at confirmed and notified cases, the impression that remains is that the pandemic is still starting in the municipality, but this is not the case. corroborated by the serological survey.

“If we consider the total population with antibodies against the nucleoprotein or those with neutralizing antibodies, we already have almost 100% of the adult population with antibodies, indicating that the pandemic may, in the coming months, be reduced to much lower levels, as observed” , he said.

“This does not mean that we will not have more cases and hospitalizations for Covid in the city of SP, but we have reached a sufficiently large number of people with antibodies that guarantees, as long as vaccination is maintained and new more infectious variants do not emerge, maintain a certain immunity. collective action to protect against hospitalizations and deaths,” he said.

In this last stage, the SoroEpiMSP survey divided the city into 160 census sectors, in which eight households were randomly selected from each. Residents of each of the randomly selected residences who were over 18 years of age were invited to participate in the research. In total, 936 blood samples were collected.

The survey also asked participants if they had received at least one dose of the Covid immunizers. According to the study, 98.2% reported having received at least the first dose of the Covid vaccine, while 91% said they had received two or three doses of the immunizer.

The first stage of the project, completed in May 2020, compared the neighborhoods with the highest number of cases and deaths per 100,000 inhabitants and pointed out that 5% of the population had already come into contact with the virus.

The second stage, completed in June 2020, showed a population-wide prevalence of 11.4%. In the third phase, carried out in July of the same year, the seroprevalence observed was 17.9%.

In October 2020, the fourth phase indicated that 26.2% of the adult population of São Paulo already had antibodies against the virus. The fifth phase, which took place in January 2021, pointed to a third of the adult population with previous infection of the disease. In the sixth stage, held between April 22nd and May 1st, this number had already jumped to 41.6%.

Finally, the seventh stage, carried out in September 2021, indicated that 81.8% of the population over 18 years of age in the city had neutralizing antibodies against the virus. At the time, 6 out of 10 adults in São Paulo had received at least one dose of the vaccine.

Upon completion of the eighth and final stage, researchers will submit data from the complete study for publication in a high-impact international scientific journal.