Vienna: Long Covid, which can last for months and even years in some people, has the potential to develop dangerous variants, scientists have found.
“Tracking the evolution of SARS-CoV-2 during persistent cases provides insight into the origin of Omicron and other global variants,” they wrote in a report on Nature.
In the report, virologist Sissy Sonnleitner, who is based at a microbiology facility in Ausservillgraten, Austria, described the case of a 60-year-old woman whose Covid infection lasted for more than seven months, in late 2020, causing relatively mild symptoms, including fatigue and cough.
Sonnleitner and her team collected more than two dozen viral samples from the woman over time and found through genetic sequencing that she had picked up about 22 mutations.
About half of them were seen in the highly mutated Omicron variant that showed up in November 2021.
“When Omicron was found, we had a wonderful moment of surprise,” Sonnleitner said. “We already had those mutations in our variant.”
While female infection was not the reason behind the emergence of Omicron, such chronic infections are, according to scientists, a prime candidate for the origin of Omicron and other variants that fueled the global Covid-19 spikes.
“I don’t think anyone has any doubt that these are a source of new variants,” said Ravindra Gupta, a virologist at the University of Cambridge, UK.
Similarly, in a 2020 report, Jonathan Li, a physician-scientist at Boston’s Brigham and Women’s Hospital, describes an eventual fatality in a 45-year-old man with a rare autoimmune disease.
The virus developed mutations linked to antibody resistance, including E484K, and another peak mutation called N501Y — both mutations were detected in a trio of fast-growing genera later named the Alpha, Beta and Gamma variants (VOCs) of concern.
Omicron also carries this mutation, as well as several others identified in the male’s infection.
“He really was the harbinger of things to come,” said Li.
Scientists have studied how the virus develops the ability to spread more easily from person to person, evade the immune response or become more or less severe.
“If a person’s immune system can’t completely clear an infection, the surviving viruses will likely carry immune-evasive mutations that helped them survive the attack,” said Darren Martin, an evolutionary virologist at the University of Cape Town in South Africa.