Photo: By Naomi S. Castellon-Perez
Researchers at Brigham and Women’s Hospital (BWH), affiliated with Harvard, have discovered that the Covid-19 antigen is twice as likely to be present in patients suffering from long Covid compared to those who experienced no prolonged symptoms. The findings, published on October 9 in the Clinical Microbiology and Infection journal, could shed light on the lingering effects of the virus. The study was conducted in collaboration with RECOVER, a National Institutes of Health (NIH) initiative aimed at understanding long Covid.
Igho Ofotokun, a leader in the RECOVER project, called the study a significant step forward. “At this stage, we don’t know what is causing this disease — we can only guess,” he said. “We have several theories, several hypotheses, so we’re testing all of those, so no stone is being left unturned.”
The study found that 43% of patients experiencing long Covid symptoms tested positive for virus-derived proteins up to 14 months after their initial Covid diagnosis, compared to only 21% of those who did not suffer from prolonged symptoms. These virus-derived proteins, or antigens, are pieces of the virus that linger in the body long after the infection has cleared.
Zoe N. Swank, the study’s lead author, believes these findings could have important implications for treatment. “For individuals that are positive for the antigen, you can then think about treating with antiviral drugs and seeing if that actually stops the replication of the virus that persists — and then maybe ameliorates their symptoms,” Swank explained.
The study coincides with RECOVER’s ongoing trial of Paxlovid, an antiviral drug being tested for the treatment of long COVID-19. David R. Walt, the primary investigator of the BWH study, emphasized the importance of this research for future treatments. “If the RECOVER-VITAL study is successful in determining that those individuals with persistent virus benefit from treatment with an antiviral drug, then our hope is our assay will be used to identify the subset of patients who can benefit from such a treatment,” Walt said in an email.
However, the study also raises important questions. While 43% of long Covid patients showed evidence of viral persistence, 57% of patients who suffer from long Covid do not have a persistent viral infection. The reasons for their ongoing symptoms remain unclear. “There are a lot of different hypotheses on how and why Covid happens,” Swank noted. “You could have an immune dysfunction that’s caused by the initial infection, or it triggers an autoimmune response, or you have a microvascular dysfunction.” told by Nature,
Daniel R. Kuritzkes, chief of the Infectious Disease division at BWH, cautioned that the study doesn’t definitively connect the presence of antigens to long Covid symptoms. “But it doesn’t seem that way — so lots of unanswered questions, even though I think it’s a well-done study,” he remarked.
Jonathan Z. Li, an infectious disease specialist and co-author of the study, agreed that the findings while promising, are far from conclusive. “This paper is really thought-provoking and intriguing, and I think it opens up this line of research and investigation that needs to be pursued,” he said. “But there’s so much that we don’t know yet.”
