A preliminary study, posted on the medRxiv prepress server and conducted by Brazilian researchers, indicated that the city of Manaus may have achieved herd immunity against the new coronavirus.
Led by Ester Sabino, from the Institute of Tropical Medicine at the University of São Paulo, the team claims to have tested antibodies to the virus in blood from blood centers. It is estimated that between 44% and 66% of the population of the Amazon capital has been infected since the city registered its first case last March.
In an interview with the MIT Technology Review, immunologist Ester Sabino stated: “From what we have learned, this is probably the highest prevalence in the world. Deaths fell very quickly, and what we are saying is that they are related ”.
The researchers say that the high mortality and the sustained fall in cases of the disease in the region indicate that herd immunity, or collective, played an important role in determining the size of the epidemic in Manaus, although other factors can be considered, such as the increase in social distancing.
The region experienced a nightmare with the virus: some died at home and indigenous groups began to be affected by the infection. However, in mid-August, a fact caused surprise and was reported worldwide: in a sudden turnaround, from a peak of 79 deaths per day, the death rate dropped to 2 or 3 daily deaths in September.
Immunologist Florian Krammer, from Monte Sinal Hospital in New York, made a warning: “Community immunity via natural infection is not a strategy, it is a sign that the government has failed to control an outbreak and is paying for it in lost lives” .
For the authors of the study: “Manaus can act as a sentinel to determine the longevity of the population’s immunity and the frequency of reinfections”.