The areas to be studied include measures to reduce viral persistence and another to alleviate brain fog, memory loss and other cognitive problems. Other treatments would address excessive sleepiness and sleep disturbances, and a fourth area involves therapies for problems involving the autonomic nervous system, which includes heart rate, breathing and the digestive system.
A fifth treatment area that is expected to focus on exercise intolerance and fatigue remains under development, and officials said they are waiting for more input from patients and scientific experts.
The first of the clinical trials, which will test a longer regimen of the antiviral medication Paxlovid on people with viral persistence, is underway.
Doctors have found in some cases that the virus persists in patients for as long as 280 days after infection.
Long covid is a diffuse constellation of more than 200 symptoms that are a ripple effect of the coronavirus, the worst public health crisis in a century. While most people who contract covid recover within days, others suffer from symptoms that can linger for weeks, months or longer, sometimes with debilitating effects.
There is no agreed-upon definition of long covid, and attempts by researchers to assess its prevalence have relied on different lists of symptoms and different time frames after patients came down with acute covid.
“The answer kind of depends on how you define the problem,” Walter Koroshetz, director of NIH’s National Institute of Neurological Disorders and Stroke, said during a news briefing Monday.
Koroshetz said some studies have suggested that 5 percent to 10 percent of people in the United States infected with the coronavirus go on to have long-covid symptoms, with the frequency higher in earlier versions of the virus than more recent variants.
An analysis of nearly 5 million U.S. patients who had covid, based on a collaboration between The Washington Post and an electronic health records company called EPIC, found that about 7 percent of those patients sought care for long-covid symptoms within six months of their initial infection. At the time, about 200 million people in the United States were known to have had covid, so that percentage translated into about 15 million with long-covid symptoms. The Post-Epic analysis also found that people with certain other health conditions were more likely to develop long-covid symptoms.
The RECOVER initiative grew out of Congress’s decision to allot more than $1 billion to NIH to understand the mysterious phenomenon of long covid and to try to find ways to treat it. The initiative began early in 2021. NIH acting director Lawrence A. Tabak said during Monday’s briefing that so far, it has involved 24,000 patients who have participated through medical exams or surveys and analyses of 60 million electronic health records.
Until now, the research sponsored by RECOVER, distributed to biomedical investigators at universities throughout the country, has been observational — meaning it has sought to describe long covid. In contrast, clinical trials test possible interventions, finding out whether treatments are safe and effective.
Patient advocates and some researchers have been impatient for NIH to begin the clinical trials, arguing they should have begun long before now.
“It’s been close to three years,” since RECOVER began, “and it really shouldn’t take that long,” said Ziyad Al-Aly, director of the Clinical Epidemiology Center at Washington University School of Medicine in St. Louis and a major long-covid researcher.
“They don’t have the sense of urgency they needed to have,” said Al-Aly, whose own research uses Department of Veterans Affairs data and does not rely on NIH funding. “There is a lot of time lost. I want RECOVER to succeed, but I also want them to have a sense of urgency around it.”
In the meantime, he said that researchers at a few universities have found other sources of support to study potential treatments for long covid, including from Pfizer, a major pharmaceutical manufacturer.