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Research eases worries that prolonged infections are contributing to the emergence of SARS-CoV-2 variants.

During the early stages of the pandemic, healthcare professionals observed that certain individuals with compromised immune systems were experiencing persistent SARS-CoV-2 infections, sometimes lasting for weeks or even months. This raised concerns about the potential for a viral variant to emerge that could take advantage of an extended battle with the immune system.

A recent prospective study published in the Lancet Microbe, led by Dr. Adam Lauring from the Division of Infectious Disease at Michigan Medicine, explores which patient populations are at a heightened risk of prolonged infections. This study, part of the CDC-sponsored IVY Network based at Vanderbilt University, closely monitored 150 immunocompromised COVID-19 patients across five U.S. health systems in 2022.

The diverse group of participants included individuals with various immunocompromising conditions, such as those with B-cell cancers or undergoing anti-B cell therapy, solid organ or stem cell transplant recipients, individuals with AIDS, and those with non-B cell cancers and autoimmune or autoinflammatory conditions.

Contrary to initial concerns, the study found that only 25% of patients tested positive using the highly sensitive PCR test for 21 days or more after the onset of illness. Only 8% tested positive for live virus for the same duration, with the median time to the last positive test being nine days.

Notably, individuals with AIDS and those with B-cell cancers were more prone to prolonged infections compared to patients with autoimmune diseases or non-B cell cancers. Among the 59 patients with solid organ transplants under T-cell immunosuppression, only one experienced an infection lasting over 56 days.

The study also highlighted a correlation between extended infections and specific immunosuppressive therapies. Patients undergoing rituximab or CAR-T therapy, which target B cells, exhibited a higher likelihood of enduring infections, underscoring the crucial role of antibodies produced by B cells in immunity.

Importantly, the study found that mutations in patients with prolonged infections rarely matched those of variants circulating globally. Dr. Lauring emphasized that a virus's ability to escape immunity differs between immunocompromised individuals and the general population.

Given the evolving landscape of global immunity through vaccination and infection, monitoring this specific patient population for new variants may not be practical. Nonetheless, the study offers valuable insights into identifying immunocompromised patients at the highest risk. Dr. Lauring hopes that this research will inspire renewed efforts to develop more effective therapies for these vulnerable individuals.

Reference: SARS-CoV-2 shedding and evolution in patients who were immunocompromised during the omicron period: a multicentre, prospective analysis. Journal: Lancet Microbe.

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