Virus used world’s longest Covid sufferer as ‘gym’ to get fitter, say scientists

The world's longest Covid sufferer had the virus for nearly 11 months during which time it mutated 40 times, using her as a "gym" to get fitter, scientists have discovered.

A Russian woman known as "Patient S" was suffering late-stage cancer when she caught Covid in April last year, having two serious bouts of illness during her infection.

She eventually tested negative this March, but during that time doctors had sequenced the virus to see how it was changing inside her body. They discovered 40 mutations, showing it was rapidly evolving.

Scientists from the Skolkovo Institute of Science and Technology in Moscow said Covid had effectively used her as a "gym" to become fitter.

"Consider the Sars-Cov-2 variants of concern that have recently spread widely and gained notoriety," said Prof Georgii Bazykin. "When such a variant originates, it often accumulates multiple mutations rapidly, just as it does when evolving in immunosuppressed individuals.

"This has led people to suggest that such individuals can be a sort of a gym for the virus where it gains the traits needed to infect humans better. While the virus we studied probably never got out of the gym, our findings imply that the gym equipment is more diverse than we thought."

The virus mutated to allow it to survive better and reproduce faster, including changes to the spike protein, which is used to enter cells. It also changed its surface proteins as if to escape antibodies, even though the patient was so immunocompromised that there were no antibodies present.

"This was puzzling,” said Evgeniia Alekseeva, the joint first author of the paper. "Why would the virus hide from something that is not there? And why would it camouflage its parts that antibodies cannot see anyway?"

Scientists said the virus may have been evolving to escape T-cells, a second part of the immunity system. Although there was no onward transmission of the mutated virus, researchers said other variants could emerge in similar ways.

Researchers believe that the alpha or Kent variant originally arose in an immunocompromised patient.

The research was published on the website Research Square.