Paxlovid, an antiviral approved in 2023 to treat acute infections of COVID-19, is showing great potential as a new treatment for long COVID and may be the most promising experimental therapy now being studied for treating the condition.
New research offers strong evidence that Paxlovid provides significant benefits for COVID-19 patients who are at high risk for severe or prolonged disease, particularly older adults and those who are immunocompromised, said Lisa Sanders, MD, medical director of Yale’s Long COVID Multidisciplinary Care Center, New Haven, Connecticut.
“We all know that long COVID is a disease smorgasbord of illnesses that have been somehow triggered by COVID. So, the question is, are there some types of these disorders that can respond to Paxlovid?” Dr. Sanders said.
Some patients have also benefited from supplements such as N-acetyl cysteine (NAC), as well as vitamins B, C, D and alpha lipoic acid, in which the risks are low and there are potential benefits, Dr. Sanders said.
A study published in 2023 by JAMA Internal Medicine reviewed the charts of nearly 300,000 veterans with severe acute COVID infections. The study found that Paxlovid treatment reduced the likelihood of developing long COVID. But a more recent study at Stanford University, Palo Alto, California — the STOP-PASC trial— did not find Paxlovid improved symptoms when given to 155 patients who had already recovered from acute infection. Participants with long COVID symptoms — and who had on average recovered from acute infection around 16 months earlier — were given a 15-day course of Paxlovid. Common symptoms like fog, fatigue, and cardiovascular or gastrointestinal symptoms did not improve.
However, long COVID likely has multiple drivers. Viral persistence may still be at play for a subset of patients. This means that, despite the fact that patients recover from acute infection, hidden reservoirs of SARS-CoV-2 are still present in the body, possibly bringing on long COVID symptoms. Which means Paxlovid may help some long COVID patients but not others, Dr. Sanders explained. That’s why research needs to continue to identify the best cases for Paxlovid’s use and to identify other treatments for those who do not benefit from Paxlovid.
The PAX LC trial at Yale suggests there may not be a one-size-fits-all treatment for the condition, but a range of factors that may determine the best therapy for individual patients. Led by Yale School of Medicine’s Harlan Krumholz, MD, and Akiko Iwasaki, PhD, the study tested the effects of Paxlovid overall and was designed to determine who is most likely to benefit from antiviral treatment and gain further understanding of the immune response in long COVID. Results should be reported soon.
“This acknowledges one line of thinking that long COVID is caused by viral persistence,” Dr. Sanders said. “Do these people have hidden reservoirs of the virus? The question is, are there people who seem to respond [to Paxlovid]? And if so, what characterizes these people?”