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Covid-19: Immunosuppression could favor the development of variants

The Could the fragility of an immune system lengthen the duration of Covid-19 infection and promote the development of its variants? The results of research carried out by King’s College London and Guy’s and St Thomas’ NHS Foundation Trust – a foundation for research and innovation in public health – give food for thought on the subject.

The study, the results of which have not been published publicly, but presented at the European Congress of Clinical Microbiology and Infectious Diseases (ECCMID) from April 23-26, 2022, suggests that Covid-19 variants could partly originate and develop in individuals with weakened immune systems by illness or medical treatments such as chemotherapyreports The Dauphine Libere.

To reach these conclusions, data from immunocompromised patients who contracted the Covid-19 virus were analyzed over several months. The study notably made it possible to reveal a “record” of longevity of the infection in one of the organisms of the persons concerned.

The person in question, now deceased, was said to have been positive for the virus for 505 days, which could be “the longest reported infection”said Dr Luke Blagdon Snell, an infectious disease expert at Guy’s & St. Thomas’ NHS Foundation Trust.

Longer Covid positivity in immunocompromised people

Of nine patients analyzed, all tested positive for Covid-19 for at least eight weeks at the time of the research, and two of them for more than a year. On average, the infection persisted in study participants for 73 days.

Thus, it turned out that theinfection persists longer in immunocompromised people. This “persistent” Covid is also different from a long Covid, for which the patients, although negative after a certain time, still feel the symptoms, but are no longer contaminated.

Congenital or acquired, immunosuppression occurs in particular in people with HIV, cancer, or who have received an organ transplant. This weakening of the immune system puts patients at increased risk of serious infections and death.

The mortality rate following contamination with Covid-19 would be 15 to 20% in immunocompromised people, revealed several associations during an appeal to the President of the Republic, published on January 1, 2022, in The Sunday Journal.

Longer infections that would promote the appearance of variants

But, beyond this very long infection, a weakened immune system, could also be the cause, at least in part, of the development of virus variants, according to British researchers.

As they tested the nine immunocompromised patients, the scientists analyzed the genetic code of the virus to ensure it was the same strain throughout the disease, not multiple infections successive. An experiment that allowed them to observe that the virus evolved over time within the body, mutating as it adapted.

This provides evidence that mutations found in variants of concern occur in immunocompromised patients and thus supports the idea that new variants of viruses can develop in immunocompromised people”, according to Dr Luke Blagdon Snell, whose remarks were relayed by The Dispatch.

The virologist explains that “these variants may have managed to evolve in immunocompromised individuals because the virus was able to persist in their body long enough to achieve this“, while specifying that this first research does not allow us to affirm that the Alpha, Delta and Omicron variants appeared in this way.

Co-author of the study, Dr Gaia Nebbia, virologist, therefore underlines the importance of developing new therapeutic strategies for these patients, “in order to eliminate the infection as quickly as possible”, but also, in the long term, to prevent appearance of new variants.

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