An infection with the coronavirus offers most people protection from re-infection in the following months. This is the result of a large-scale study in Denmark, which has now been presented in the journal The Lancet. However, repeated infections are more common in older people over 65 than in younger people.
The authors of the study analyzed extensive data that was collected in Denmark as part of a national corona test strategy and spanned the first and second corona waves. More than four million people were tested with free PCR tests at Germany’s northernmost neighbor in 2020; The Danes also use the results for research purposes.
According to the scientists, the PCR tests were twice positive in 0.65 percent of the patients during the first and second corona waves. For comparison: the test of those who tested negative during the first wave from March to May 2020 was positive in 3.27 percent of the patients during the second in the following September to December. The researchers gave protection against repeated infection for younger people at 80 percent – for people over 65, however, with only 47 percent.
Don’t rely on natural protection
“Our study confirms what a number of others have already indicated,” said one of the study’s authors, epidemiologist Steen Ethelberg from the Danish health institute SSI. “New infection with Covid-19 is rare in young, healthy people, but older people have a higher risk of being infected again.” explained the author Daniela Michlmayr.
According to the researchers, these findings show that measures to protect the elderly, such as keeping your distance and vaccinating, are also fundamental for those who have already had Covid-19. Your analysis continues to suggest that people who have already contracted the coronavirus should also be vaccinated. The elderly, in particular, cannot rely on natural protection.
The researchers point out that given the time frame of the study, it was not possible to assess protection against repeated infection with the virus variants. Variant B.1.1.7, which first appeared in England, now accounts for more than 90 percent of all new corona infections analyzed in Denmark.
The new data are worrying, “The Lancet” quotes researchers Rosemary J. Boyton and Daniel M. Altmann from Imperial College London, who were not involved in the study. “All of this data confirms that in the case of Sars-CoV-2, the hope of protective immunity through a natural infection may not be within reach and that a global vaccination program with highly effective vaccines is the permanent solution.”