As the pandemic drags us into a fourth year, two key questions are on researchers’ minds: What’s driving the proliferation of immune-evasive variants, and what’s causes the persistent symptoms plaguing some 140 million Covid survivors worldwide?
Answers to both have been informed by two different and somewhat unsavory lines of inquiry.
In the spring of 2020, when it was widely assumed Covid was purely a respiratory disease, critical care physician Dan Chertow began recruiting participants for a study to find out where the coronavirus goes in the body, how long it stays, and what it does there.
Using meticulous analytical methods, he and his colleagues at the National Institutes of Health in Bethesda, Maryland, found the virus traverses the entire body and brain, where it can persist for months.
The study, published in the journal Nature in December, raised lots of questions, including whether lingering vestiges of SARS-CoV-2 in patients are causing long Covid symptoms. Chertow’s research was based on autopsies of people who died from Covid and he had no information on any unrelenting symptoms they might have had after catching the virus, so he couldn’t answer that question.
But the findings sparked intense efforts by other scientists to locate viral reservoirs in long Covid patients as well as clinical trials to counter prolonged infections with Paxlovid and other antiviral treatments.
Meantime, Marc Johnson, a virologist at the University of Missouri, has been studying viral persistence in a different way. He and colleagues have been hunting for unusual coronavirus strains in wastewater and studying the mutants over time to learn what genetic changes help them evade the immune system and what new iterations omicron could throw up next.
Johnson’s work has demonstrated that some individuals are shedding SARS-CoV-2 in their fecal waste for a year or more, incubating worrisome immune-evasive variants in their digestive tracts.
Finding these chronically infected individuals, learning why the virus is hiding out in their bodies, and finding ways to vanquish the infection might not only stem the emergence of worrisome variants, it could also provide relief for millions of long Covid sufferers. —Jason Gale