Infected despite vaccination – health


The Sars-CoV-2 vaccines that have so far been approved in Europe all protect well against infection with the coronavirus. But their protection is not perfect. Rarely, “breakthrough infections” occur when the virus manages to affect a person who has already been fully vaccinated. The Robert Koch Institute has registered a little more than 6000 such cases since the vaccination campaign began last year. There were probably more that have not yet been noticed. With over 40 million people fully vaccinated, these numbers are tiny, but they still deserve attention.

A new study shows that the risk of vaccine breakthrough is related to the number of antibodies a person makes after vaccination against the virus. The data come from the largest medical care center in Israel, whose employees were vaccinated with the mRNA vaccine from Biontech / Pfizer. 1497 of them had swabs taken from the nasopharynx, which were examined by PCR. 39 infections were found, most of which caused no or only mild symptoms in those affected. On average, those infected had developed weaker immune responses than those who were not infected during the study period.

“A well-done study that shows the connection between the amount of antibodies and the risk of infection,” says Reinhold Förster from the Institute for Immunology at the Hannover Medical School (MHH). “However, it also shows that the range of the immune response is very wide.” There were also some with very high antibody levels among those infected. “It is not yet possible to use the amount of antibodies to predict who is still at high risk of infection despite being vaccinated, and who is not,” says Förster, who recently joined his team was able to show in an employee investigation by the MHHhow different the immune response to a Sars CoV-2 vaccination can be.

“We expected that there would be a connection between immune response and protection,” says Christine Falk, immunologist at the MHH and president of the German Society for Immunology. “There are people who respond very well to a vaccination and some who don’t respond quite as well.” These so-called low responders are the exception, not the rule, which is also reflected in the low number of vaccine breakthroughs so far. Falk compares the one with the weaker immune response to a defensive defense in a soccer game. “Sometimes a virus comes through, but then there are other parts of the immune system that have nothing to do with antibody production and prevent serious illness in the vast majority of cases.”

All vaccines were developed against the original virus, which was far less infectious than the currently prevailing Delta variant. “Most of the low responders were still armed against the original virus,” says Falk, “but against the Delta variant, more antibodies are necessary to fight off an infection.”

Because the Delta variant is so much more infectious than the original virus, scientists from the American Disease Protection Agency (CDC) compared the mutant in an internal paper with chickenpox, which is also highly contagious. According to preliminary data from the agency, vaccinated people who nevertheless become infected with Delta can sometimes be just as contagious as unvaccinated infected people. Therefore, vaccinated people should continue to wear masks indoors. A demand that Christine Falk supports. “Vaccination breakthroughs need not worry us if they remain isolated and do not pass the virus on.” Therefore, she emphasizes the importance of the other protective measures: distance, masks, ventilation and testing. All of this must continue to apply until the vast majority of people are really immune to the virus. “Just relying on the vaccination is not enough.”

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