Another group that writes The New England Journal of Medicine Earlier this month, he detailed the trajectory of the virus in a 45-year-old man with an autoimmune disorder for which he was receiving immunosuppressants. In this case, they found that there was an “accelerated” evolution of the virus in the individual and many of the mutations were in the spike protein. Most immunocompromised individuals eliminate SARS-CoV-2 infections without major complications, they wrote, but “this case highlights the potential for persistent infection and the accelerated viral evolution associated with an immunocompromised condition.”
The same phenomenon has been observed in other conditions in which the immune system is impaired. HIV attacks immune function, which allows it to evolve at an astonishingly high rate, making it even harder for the body to continue to produce antibodies that bind and neutralize the virus. By the same mechanism, HIV infections allow other viruses in the individual to last longer and transform. The herpes simplex virus can evolve into unusual drug resistance in AIDS patients, for example.
However, we need a better understanding of immunocompromised patients who are most vulnerable to long-term SARS-CoV-2 infection. The “immunocompromised” category encompasses such a wide range of different conditions and not all may pose the same risk of persistent Covid-19. Brian Wasik, a virologist at Cornell University, points out that the term may include people born with rare disorders that impair their ability to fight pathogens, as well as those taking immunosuppressants to allow a transplant or to calm an autoimmune disease.
Evidence of links between immunocompromised individuals and persistent SARS-CoV-2 infections and between persistent infections and viral development is sufficiently convincing to be considered in discussions about vaccine priority. On Sunday, a group at the US Centers for Disease Control and Prevention recommended that immunocompromised individuals be placed in “Phase 1c” – the third wave – of vaccine launches. This means that they will receive the injections at the same time as those with cancer, coronary heart disease or obesity, among other conditions. This decision was intended to address the specific risks posed by Covid-19 to people with immune problems, but ruled out the possibility that vaccination of these individuals would help prevent the development of new SARS-CoV-2 variants that would cause this pandemic. even worse than it already is. For this reason, even if there are only a handful of directly relevant case reports, public health officials should consult with virologists as to whether it might be wise to move immunocompromised individuals to the previous phase 1b group.
At the very least, we need better monitoring of potential SARS-CoV-2 changes. The US government should do more to help organize viral sequencing efforts. CDC has a program called Spheres that tried to capture sequence data during the pandemic, but fails: If the UK sequenced about 10 percent of its Covid-19 cases, the U.S. succeeded in only 0.3 percent . “It’s a bit uneven,” says Adam Lauring of the University of Michigan School of Medicine, who adds that his team uploaded about 2 percent of the sequence data from the United States. “There are large areas of the country where there are no people to spend a lot of time and effort” for this task. Better monitoring of viral evolution could also help clarify the question of exactly where – in which patients – these changes are most likely to accumulate.
As we monitor SARS-CoV-2 mutations, we must recognize that understanding their epidemiological and clinical significance requires further work. Meanwhile, the virus is still rampant, giving it more opportunities to move even as it spreads from person to person. But long-term infections in some immunocompromised individuals and the associated potential for viral evolution should be a focus of attention.
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