Swedish scientists have come to the conclusion that the level of collective immunity to coronavirus can be twice as high as previously thought, and it can even form in people with negative antibody tests.
Researchers at the Karolinska Institute in Stockholm conducted an immunological analysis of samples of more than 200 patients, many of whom had mild or completely asymptomatic disease.
It is noteworthy that, unlike other scientists, specialists from Sweden – the only European country that has not introduced serious restrictive measures against the backdrop of COVID-19 – do not write off the development of immunity to the presence of antibodies to the virus in the human body.
Moreover, they believe that so far the attempts to “measure” the level of immunity in the population have mainly failed because of the fact that the emphasis in the study was on antibodies. As the Daily Mail reports citing the study, in addition to studying antibodies, scientists drew attention to the level of T-lymphocytes or T-cells in patients. The fact is that they play a crucial role in the formation of immunity to transferred infectious diseases.
In addition, they store information about previously acting antigens, due to which they form a quick secondary immune response while destroying a dangerous pathogen. Therefore, they are often called T-killers.
According to the results of the study, the so-called “T-cell immunity” was found in 30% of healthy blood donors. Moreover, it was two times higher than those in which antibodies were detected in the body.
This means that more people, without suspecting it, may have developed protective properties against COVID-19. However, scientists still do not know how long the immunity to coronavirus lasts with the T-cell response. It is believed that antibodies retain their protective function from three to six months.
“This means that we are likely to underestimate the number of people who have some kind of immunity,” says Marcus Baggert, associate professor at the Carolina Institute. “Does this mean that such people are fully protected, or in the future their disease will proceed in a milder form or asymptomatically, it’s hard to say.”
Co-author of the study, Professor Hans-Gustav Lundgren, added that this discovery was “very good news in terms of public health.”
T cell analysis is known to be much more complex than an antibody test. Currently, it is carried out only in specialized laboratories.