An infection with seasonal cold corona viruses should – at least temporarily – protect against Covid-19. Scientists have found evidence of cross-reactive antibodies. Vaccination continues to offer the best protection.
There is apparently a close connection between coronaviruses, which have long been known to cause coughs, runny nose and hoarseness, and SARS-CoV-2. An infection with the harmless seasonal known corona viruses should at least temporarily protect against Covid-19. A Swiss team of scientists has now found new evidence for cross-reactive antibodies.
SARS-CoV-2 is not the only coronavirus that occurs in humans. Four similar viruses – OC43, HKU1, NL63 and 229E – are classic causative agents of seasonal colds. “Children in the first years of life are particularly affected. Later, an immunity sets in that protects adults from diseases that may be more severe for them,” wrote the German medical journal about the scientific results.
The corresponding study by Zurich scientist Alexandra Trkola was published a few days ago in the magazine “Nature Communications”. In it, the influence of immunity against the “old” coronaviruses on the risk of infection from SARS-CoV-2 and the risk of disease from Covid-19 was examined. The team of authors from the University of Zurich used a specially developed test to examine the amount of different antibodies against the long-known seasonal coronaviruses found in humans in the serum of 825 blood donors from the time before the occurrence of SARS-CoV-2. They were compared with 389 samples from donors who were infected with Covid-19.
“The researchers were able to show that people who were infected with SARS-CoV-2 had lower levels of antibodies against the common cold coronavirus. In addition, SARS-CoV-2 infected people with high antibody levels against the harmless coronavirus had to be hospitalized less often it said in a broadcast from the Swiss university.
Study author Trkola commented on the results as follows: “According to our results, a stronger antibody reaction against human coronaviruses also leads to higher amounts of antibodies against SARS-CoV-2. A person who has immunity against harmless coronaviruses is therefore also better off from severe courses of SARS -CoV-2 infections protected. ” This cross-reactivity does not only occur with antibodies as part of the immune response. The same apparently applies to the immune response of T cells, the second pillar of the human immune system. Immune cells that act specifically against coronavirus-infected cells also fight SARS-CoV-2.
However, one should by no means rely on such an immune reaction. The Covid-19 vaccination is much better. The antibodies against the harmless coronaviruses disappear again. “But although the protection is not complete, cross-reactions shorten the course of the disease and alleviate its severity. And that is exactly what we achieve with vaccinations, only much, much more efficiently,” emphasized the scientist.
It remains to be seen whether this cross-reactivity also works the other way round. So whether an immunity to SARS-CoV-2 – for example through a vaccination – protects against other human coronaviruses. “If SARS-CoV-2 immunity also offers a certain protection against infection from other coronaviruses, we would come a big step closer to comprehensive protection against coronaviruses, including newly emerging variants,” the Zurich virologist was quoted as saying by her university. In any case, this assumption is supported by the fact that a cross-reactive protective effect is not only based on antibodies, but very likely also on T cells.
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