The 60-year-old woman tested positive for Covid-19 within seven months and “produced” 22 different virus mutations during that period, according to a virologist from Austria, where the woman was being monitored.

An elderly woman tested positive for Covoid-19 within seven months in 2020 – Photo: Prasesh Shivakoti/Unsplash/ND

According to R7, she became infected in 2020 and had taken immunosuppressive drugs for her lymphoma prior to Covid-19. However, at the time of infection, she had mild symptoms such as coughing and fatigue.

The researchers analyzed more than 24 virus samples from an elderly woman and noticed that half of the mutations were found in the Omicron variant, which appeared in late 2021.

“When Omicron was found, we were in for a big surprise. […] We already had these mutations in our variant,” Sissi Teresa Sonnleitner told Nature.

However, the virologist claims that the variant did not arise through the infection of a woman, since it was not transmitted to other people.

Even without evidence, chronic infections such as that of an elderly woman are prime candidates for the origin of Ômicron and other variants of Covid-19.

“I think no one can doubt that these [infecções longas] are a source of new variants,” added Ravindra Gupta, a virologist at the University of Cambridge, to Nature.

worldwide effort

Scientists have sequenced the genomes of more than 11 million virus samples taken from patients since the end of 2019. In this way, you can “draw” the evolutionary tree of the virus, which shows how it has changed over the years.

According to the study, new mutations arise in the same way that an infection spreads from cell to cell, but not all of them are harmful. However, there are others that can add advantages over other versions of viruses in the body and increase the ability to infect or resistance to immunobiological protection.

In acute infections that last about a week or two, mutations have less time to overcome weaker ones and theoretically reduce the possibility of transmission.

However, the study shows that only a few viral particles are needed for a new infection to occur. Thus, the probability of infection becomes uncertain.

“Which of these viruses is in an aerosol droplet that you sneeze the moment someone walks by and inhales depends largely on luck,” Jesse Bloom, an evolutionary biologist at the Fred Hutchinson Cancer Center in Seattle, told Nature. .

In chronic infections, which can last weeks or months, viruses with “favorable” mutations have more time to overcome others. In a process called recombination, which involves combining the genetic material of two strains, more suitable viruses can be produced.

“These viruses have the ability to evolve not just in one direction, but literally in thousands, if not tens of thousands of directions over the course of months,” warned Sarah Otto, an evolutionary biologist at the University of British Columbia.