London, Dec 21 (IANS): The hypothesis that the emergence of new Covid-19 variants could be linked, in some cases, to untreated HIV is "highly plausible", according to South African scientists.

To explore the link, a team of scientists have launched a probe into mutations taking place inside infected people whose immune systems have already been weakened by other factors, including, though not limited to, untreated HIV, BBC reported.

It has already been observed that Covid-19 can linger for many months in patients who are HIV-positive but who have, for varying reasons, not been taking the medicines that would enable them to lead healthy lives.

"Normally your immune system would kick a virus out fairly quickly, if fully functional," Professor Linda-Gayle Bekker, Chief of Desmond Tutu HIV Foundation in Cape Town, was quoted as saying.

"In someone where immunity is suppressed, then we see viruses persisting. And it doesn't just sit around, it replicates. And as it replicates it undergoes potential mutations. And in somebody where immunity is suppressed that virus may be able to continue for many months -- mutating as it goes," she added.

In line with this, the researchers found a South African woman who continued to test positive for Covid-19 for almost eight months, earlier this year, while the virus underwent more than 30 genetic shifts, the report said.

About "10 to 15" similar cases had been found in other parts of the world, including the UK, Professor Tulio de Oliveira, who leads the team that confirmed the discovery of Omicron, was quoted as saying.

"It's a very rare event. But it is a plausible explanation that individuals that are immuno-suppressed can basically be a source of virus evolution," he said.

The link between immuno-suppressed patients and new Covid variants is "a highly plausible hypothesis", said Professor Salim Karim, a leading HIV specialist and former chair of the South African government's Covid-19 advisory committee.

"But it's not proven. We've seen five variants come from four different continents," Karim added.

At the same time, the scientists noted that they are anxious to avoid further stigmatising people living with HIV, both in South Africa -- home to the world's largest HIV epidemic - and globally.

"It's important to stress that people who are on anti-retroviral medication - that does restore their immunity," Bekker said.

But scientists tracking the virus say they hope that concern about a potential link with HIV will spur greater global action at a time when the fight against HIV has been neglected, in some areas, because of the pandemic.