Scientists are growing concerned that infections of the SARS-CoV-2 virus may be triggering more cases of chronic fatigue syndrome or myalgic encephalomyelitis (ME/CFS).
A new study has found that six months or longer after a SARS-CoV-2 infection, participants were 7.5 times more likely to meet the diagnostic criteria for ME/CFS than those who had not been infected.
“Our results provide evidence that the rate and risk of developing ME/CFS following SARS-CoV-2 infection is significantly increased,” write the authors of the study, led by ME/CFS researcher Suzanne Vernon of the Bateman Horne Center in the US.
Their results, the researchers add, “are supported by other studies that have implicated infectious agents such as Epstein-Barr virus and Ross River virus and non-viral diseases such as Q fever and giardiasis in the etiology of ME/CFS.”
While no one knows what causes ME/CFS, viral infections are thought to be a possible trigger.
Long COVID and ME/CFS share many overlapping symptoms, and some scientists suspect the two illnesses are somehow related or triggered by the same factors.
In fact, current estimates suggest between 13 and 58 percent of people with long COVID meet the diagnostic requirements for ME/CFS.
Before the 2020 pandemic, the health burden of ME/CFS in the US was estimated to be double that of HIV/AIDS.
Now that long COVID has impacted more than 18 million adults, some researchers predict we could be facing twice as many cases of ME/CFS in the near future.
The current study was funded by the US National Institutes of Health, and it included 11,785 participants who had had COVID-19 at least six months prior and 1,439 uninfected participants.
Importantly, no participant in the analysis had pre-existing ME/CFS, and most were vaccinated against COVID-19.
In the end, 4.5 percent of participants who had fallen ill with COVID-19 met the criteria for CFS/ME, which typically requires at least six months of fatigue, accompanied by post-exertional malaise, cognitive impairment, unrefreshing sleep, or orthostatic intolerance.
Of that group, 89 percent also met the criteria for long COVID.
This may indicate that ME/CFS after COVID-19 “represents a severely ill subset” of long COVID patients, the authors hypothesize. But more research is needed to disentangle these two diagnoses, especially since both illnesses are highly variable from patient to patient.
While 4.5 percent may not seem like much, it’s many times higher than the rate before 2020. What’s more, nearly 40 percent of infected participants were deemed “ME/CFS-like“, meaning they displayed at least one ME/CFS symptom six months after COVID-19.
By comparison, only 0.6 percent of uninfected participants met the diagnostic criteria for ME/CFS, and 16 percent of them had just one symptom.
Post-exertional malaise, which is when symptoms get worse after exertion, was the most common symptom reported by all participants with ME/CFS.
Orthostatic intolerance, where standing leads to low blood pressure and an elevated heart rate, was the next most common symptom.
Long COVID, meanwhile, tends to be marked by lingering symptoms of COVID-19 itself, like respiratory issues or chest pain.
“Compared to those never meeting ME/CFS criteria in the infected cohort, those with post-COVID-19 ME/CFS were more likely to be White, female, between 46 and 65 years of age, and live in a rural area, and less likely to have been vaccinated at enrollment and to have completed college,” explain Vernon and her colleagues.
Figuring out why some people are more susceptible to long COVID or ME/CFS could help researchers find new avenues for prevention and treatment of both diseases.
Given that neither has a known cause or cure, and both are on the rise, there’s every reason to keep digging.
The study was published in the Journal of General Internal Medicine.
