Anyone who has recovered from a COVID 19 disease may still be immune to the coronavirus eight months after infection. A new study has come to this conclusion. The interpretation of the results gives a positive signal: immunity against the virus may last for several years. Should this be confirmed, the fear that the corona vaccination would have to be repeated several times to get the pandemic under control will alleviate.

Fear of poor immune memory “Originally there were many concerns about whether the virus could be easily remembered by the immune system,” says Shane Crotty, virologist and professor at the La Jolla Institute for Immunology in California and co-author of the new paper. “Instead, the immune memory seems to be pretty good here.”

The study published last week in the science magazine Science contrasts with previous results that suggested that immunity against Covid – 19 could only be of short duration, so that millions of those who have already suffered an infection would be exposed to the risk of re-infection

This dilemma would not have been surprising, since infections with other coronaviruses – such as the famous annual colds – usually produce antibodies that disappear again quite quickly. However, according to the new study, re-infection should only be a problem for a small percentage of the already immune population.

Vaccination and infection: B cells remain This apparently applies to both previously infected and healthy people as well as to vaccinated people. In fact, the study also suggests that a small number of recovered people do not develop long-term immunity. But vaccinations should compensate for this problem by creating herd immunity in the majority of the population.

Crotty’s paper examined blood samples from 185 Men and women who have recovered from Covid – 19 – most of them after a mild infection, though seven percent were also hospitalized were. Each person gave at least one blood sample between six days and eight months after the first symptoms appeared. 43 the samples were taken after six months.

The team that conducted the investigation calculated the Degrees of different immunological markers that work together to prevent re-infection: antibodies (which mark pathogens for the body to either destroy or neutralize in their activity by the immune system), B cells (which produce antibodies) and T cells ( kill the infected cells).

Moderate decrease after eight months The team of scientists found that Antibodies decreased moderately in the body after eight months, although there were large differences in degree between individuals. The number of T cells, on the other hand, decreased only modestly and the number of B cells remained constant or even increased in part – as yet unexplained –

This means that free antibodies are decreasing, but the components that can restart their production and coordinate an attack on the coronavirus remain in considerable quantities.

Crotty believes that the same mechanism that leads to an immune memory after an infection, also forms the basis for immunity after a vaccination – the same development can therefore be assumed in vaccinated people.

Comparison with other coronaviruses In general, the immunity with other coronaviruses is not exactly outstanding. However, a comparison with SARS – the predecessor or cousin of the new coronavirus, so to speak – shows that the corresponding T cells remain in the body for up to 17 years . This gives reason to hope that the immunity to Covid – 17 could possibly last for decades.

The La -Jolla study is not perfect, which the researchers around Crotty also admit. So it would have been better to take several blood samples from each subject. “Immunity varies from person to person and individuals with an unusually weak immune memory may still be susceptible to re-infection,” warns the virologist.

No firm conclusions can be drawn about immunity to Covid – 19 move before years have passed. “It’s just too early for that.” Nevertheless, the results are a good indicator that a functioning and long-term vaccination campaign can end the pandemic.

(bsc)