Another group, writing in The New England Journal of Medicine earlier this month, detailed the trajectory of the virus in a 45-year-old man with an autoimmune disease for which he was receiving immunosuppressants. In this case, they found that there was an “accelerated” evolution of the virus in the individual, and a lot of mutations were in the spike protein. Most immunocompromised people clear SARS-CoV-2 infections without major complications, they wrote, but “this case highlights the potential for persistent infection and accelerated viral evolution associated with an immunosuppressed state.”
The same phenomenon has been observed in other conditions where the immune system is hampered. HIV attacks immune function, which allows it to evolve at an incredibly high rate, making it even more difficult for the body to continue to make antibodies that bind and neutralize the virus. By the same mechanism, HIV infections allow other viruses in the individual to last longer and to transform. The herpes simplex virus can develop unusual drug resistance in patients with AIDS, for example.
Nevertheless, we need to better understand exactly which immunocompromised patients are most vulnerable to long-lasting infection with SARS-CoV-2. The category of ‘immunocompromised’ encompasses such a wide range of different conditions, and they do not all confer the same risk of persistent Covid-19. Brian Wasik, a virologist at Cornell University, points out that the term can include people born with rare diseases that decrease their ability to fight pathogens, as well as those who take immunosuppressants to allow for transplantation or to quell an auto disease. -immune.
The evidence for links between immunocompromised individuals and persistent SARS-CoV-2 infections, and between persistent infections and viral progression, is convincing enough to be considered in discussions about vaccine priority. On Sunday, a panel from the United States Centers for Disease Control and Prevention advised that immunocompromised people are put in “Phase 1c” – the third wave – of vaccine deployment. This means that they must receive the injections at the same time as those with cancer, coronary heart disease or obesity, among other conditions. The move was intended to address the particular risks posed by Covid-19 to people with problems with their immune systems, but it left out the possibility that vaccinating such people could help prevent the development of new variants of SARS-CoV- 2 that would make this pandemic even worse than it already is. For this reason, even though there are only a handful of directly relevant case reports, public health officials should consult with virologists on whether it would be wise to transfer immunosuppressed people to the phase group. 1b earlier.
At the very least, we need better monitoring for potential changes in SARS-CoV-2. The US government should do more to help organize viral sequencing efforts. The CDC has a program dubbed Spheres who tried to capture sequence data during the pandemic, but it fails: where the UK has sequenced an estimate 10 percent of his Covid-19 cases, the United States has only managed 0.3 percent. “It’s a bit spotty,” says Adam Lauring of the University of Michigan School of Medicine, who adds that his team downloaded about 2% of the variant sequence data in the United States. “There are large areas of the country where there are no people who devote a lot of time and effort” to this task. Better monitoring of viral progress could also help clarify the question of exactly where – in which sick people – these changes are most likely to accumulate.
As we monitor SARS-CoV-2 mutations, we must recognize that understanding their epidemiological and clinical importance requires further work. Meanwhile, the virus is still rampant, giving it more opportunities to mutate even as it spreads from person to person. But long-lasting infections in some immunocompromised individuals and the associated potential for viral development should be the focus of attention.
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