There is hardly any place where masks are still compulsory, individual federal states are abolishing the obligation to isolate in the event of a corona infection - but these relaxed rules do not mean that the virus should be regarded as completely harmless. It's not just a cold, as the virologist Sandra Ciesek recently emphasized on Twitter. The results of a US study also show that multiple infections with the coronavirus are associated with a significant risk to health.
Researchers at Washington University School of Medicine in St. Louis examined anonymized medical records from US veterans. The researchers evaluated data from around 41,000 people who had two or more corona infections between March 1, 2020 and April 6, 2022. 443,000 people who only had Covid-19 once and 5.3 million people who had not yet been infected with the corona virus served as control groups.
Their result: Reinfected corona patients had a more than twice the risk of death and a more than tripled risk of hospitalization compared to patients who had only been infected with Covid-19 once. The scientists also found an increased risk of problems with the heart, lungs, kidneys, mental health, bones, muscles and neurological disorders.
The different corona variants were taken into account in the study: delta, omicron and the omicron subline BA.5. The results are independent of the vaccination status.
"Our research has clearly shown that a second, third or fourth infection contributes to additional health risks in the acute phase, i.e. the first 30 days after infection, and in the months thereafter, i.e. in the long Covid phase." , study leader Ziyad Al-Aly said in a statement on the study. In recent months, vaccinations and infections have made some people feel invincible, but the study results paint a different picture. The risk of health problems seems to increase with every infection. For the researcher it is clear: "It is better to avoid a third corona infection, even if you have already had two Covid 19 infections. And if you have had three infections, it is best to avoid the fourth."
However, there is a limiting component to the study: The population from the veterans' database does not correspond to the general population, experts tell "Reuters". Because: Patients in the health facilities of the US Veterans Department are mostly older, sicker people and often men. A group that has more health complications than normal, said John Moore, professor of microbiology and immunology at Weill Cornell Medical College in New York.
Nevertheless, it can be deduced from the study that reinfection is not per se less dangerous than the first Covid 19 infection. In people with a healthy immune system, however, repeated infection with Covid-19 is usually milder. However, that depends on the variant and the time of reinfection, said Martina Prelog, immunologist at the University Hospital in Würzburg, in an interview with the star.
Sources: Study in Nature Medicine, Study Notice, Reuters, Twitter