Berlin, 21 April 2024 (dpa/MIA) — Researchers from the Netherlands have reported an extremely long Covid-19 infection in a man who died last year – and warn of the emergence of more dangerous variants of the coronavirus.

The elderly man, who was immunocompromised due to previous illnesses, was admitted to a hospital in Amsterdam in February 2022 with a Covid-19 infection, according to a statement.

He was continuously positive for the coronavirus until his death in October 2023 for a total of 613 days.

Other cases of very long infections in people whose immune systems were unable to adequately fight the virus have previously been reported.

The researchers led by Magda Vergouwe from the University of Amsterdam plan to present the results at a congress of the European Society for Clinical Microbiology and Infectious Diseases in Barcelona on April 27-30.

The case is also interesting for researchers because the coronavirus can change particularly strongly in such long-term infected people. This harbors the risk of variants of the virus emerging that can more easily overcome the immune system of healthy people.

The researchers in the Netherlands repeatedly took samples from the man in order to analyze the genetic material of the coronavirus.

They found a total of more than 50 mutations compared to the Omicron variant BA.1 that was circulating at the time, including those that would allow the virus to evade the immune defense.

Just 21 days after the man had received an anti-coronavirus drug, the virus also developed signs of resistance to it.

The man eventually died from a flare-up of one of his previous illnesses. As far as is known, he had not infected anyone with his mutated version of the coronavirus, also known as SARS-CoV-2.

This case "highlights the risk of new immune-evasive SARS-CoV-2 variants emerging in immunocompromised patients," the researchers are quoted as saying in the press release.

The extensive mutations of the pathogen in a single patient could lead to the emergence of more dangerous variants that can bypass the immune system of healthy people, they warn.