A lot of viral illnesses can completely wipe you out, and as we’ve learned throughout the pandemic, COVID-19 is no exception. But as conversations about the impact of long COVID continue to swirl, scientists are exploring just how common chronic fatigue might be after a bout with the virus.
Turns out, the risk is higher than you might think, according to a new study from the CDC published in the journal Emerging Infectious Diseases. Researchers analyzed the electronic records of 4,589 adults who received health care in the state of Washington and were diagnosed with COVID between February 2020 and February 2021 (meaning they were infected with earlier strains of SARS-CoV-2). They compared them to the records of people who didn’t test positive for the virus during the same period (those with a suspected case or a history of COVID were excluded from this control group). On average, the researchers followed up with people for about a year post-infection.
The results are sobering: People who were sick with COVID had a 68% higher risk of developing “incident” fatigue, which refers to intense tiredness that develops after what’s considered enough time to be recovered, or the “post-acute” period. (There is no single definition for this, but the National Institutes of Health notes that COVID’s post-acute period has generally been defined as three weeks after symptoms first hit.)
The study found that folks in the COVID group were also 4.3 times more likely to develop chronic fatigue—enduring exhaustion, in simplest terms—than those in the control group. The researchers noted that, in past studies, people who had post-COVID fatigue experienced symptoms that were similar to the “profound” fatigue that’s signature to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), a serious and potentially disabling condition that is often, but not always, triggered by an infection.
In general, women and people with certain underlying conditions, like diabetes or COPD, were hit by fatigue the hardest. “Physicians should be aware that fatigue might occur or be newly recognized [more than a year] after acute COVID-19,” the study authors concluded.
Unpacking the COVID/fatigue connection
Long COVID is still a bit of a mystery: There’s a lot that experts don’t understand about the condition, including why it develops in the first place.
But there are some theories: In people with long COVID, “the immune response to the virus may cause direct or indirect damage that disrupts other body functions,” senior study author Quan Vu, MD, an epidemiologist at the National Center for Emerging and Zoonotic Infectious Diseases at the CDC, tells SELF. (This would help to explain its vast and ever-growing list of potential symptoms.)
Another biggie: “We believe, in long COVID, that many people have this ongoing inflammatory response,” Thomas Russo, MD, professor and chief of infectious disease at the University at Buffalo in New York, tells SELF.
When your immune system reacts to a possible threat—in this case, an infection—it uses an “army” of specialized cells and proteins to fend off whatever’s making you sick. “With long COVID, it’s as though the army keeps fighting even though it should go back to the barracks,” William Schaffner, MD, an infectious disease specialist and professor at the Vanderbilt University School of Medicine in Nashville, tells SELF. That inflammation, experts believe, “continues to smolder for a long period of time,” he explains, triggering a slew of potential symptoms, including persistent fatigue.