Long COVID-19 has persisted as a mysterious disease affecting millions of people since the start of the pandemic. Despite this and the large number of studies that have been conducted to demystify the range of symptoms many people experience after acute infection, the medical community is still a long way from being able to effectively treat and diagnose the condition.
There is no proven treatment, and a survey of more than 1,100 global physicians found 87 percent feel there is a lack of treatment guidelines. However, patterns have started to emerge as to what drives long COVID-19.
"Most diseases like this take years or decades to understand the underlying mechanism," Akiko Iwasaki, PhD, a professor of immunobiology at Yale University in New Haven, Conn., and principal investigator at the Howard Hughes Medical Institute, told Becker's. "We are doing everything as fast as we can, [and] in other laboratories as well. But we're just looking at the tip of the iceberg right now."
Dr. Iwasaki spoke with Becker's about her long COVID-19 research and what it could mean for similar diseases. Her research focuses on the mechanisms of immune defense against viruses and has conducted nearly a dozen studies on long COVID-19.
Looking at her research, she suspects there is more than one cause for the disease.
"My suspicion is that there will be several root causes that drive this long COVID-19 disease, and people may have combinations of these things happening while others have one of these striving," Dr. Iwasaki said.
Among these suspected causes are persistent viral antigens, autoimmunity and latent virus reactivation.
She said she also noticed a trend of Epstein-Barr virus reactivation, which can be triggered by stress, a weak immune system or hormone changes. A study published in Cell earlier in 2022 identified four predictive factors for developing long COVID-19 during the acute phase, which included EBV levels in the blood. Though the study focused on early-stage COVID-19 and was not enough to determine a causal link, the research has helped connect other studies that have also seen EBV reactivation in long COVID-19 patients.
"That's something I think is sort of converging on a, I wouldn't say consensus, but at least we're seeing some patterns," Dr. Iwasaki said.
Long-term consequences for infections are not a new phenomenon but have largely been ignored by the medical community because it is hard to assign a particular reason for their occurrence, according to Dr. Iwasaki.
For instance, myalgic encephalomyelitis/chronic fatigue syndrome, or MECFS, is a long-term condition with unknown causes, though some theories exist as to what triggers it. Such theories include viral or bacterial infections, and problems with an individual's immune system.
"Long COVID … is shining light onto these other types of post-acute infection syndromes like MECFS because there are tens of millions of people that are suffering with long COVID," Dr. Iwasaki said.