Harvard professor Andrew T. Chan discussed how researchers are studying “long Covid” — a condition characterized by Covid-19 symptoms that linger after a patient initially recovers from the virus — at a Thursday event jointly hosted by the Harvard School of Public Health and radio program The World.
Elana Gordon — a global health reporter at The World, a Boston-based radio program — moderated the event, which featured talks on a Covid-19 symptom study app launched in March 2020 under Chan’s leadership. The app has collected real-time data on virus symptoms from over four million users in the United States, the United Kingdom, and Sweden.
Chan, a professor of medicine at Harvard Medical School and immunology at the School of Public Health, explained that epidemiology studies — in which the spread of a disease and its causes are researched — are typically conducted over a long period of time. The rapid onset of the Covid-19 pandemic, however, made data collection via traditional methods difficult.
“We realized very early on that one of the biggest challenges of the pandemic was really being able to collect high-quality data that represented a broad segment of the population that could really give us some information about a disease that no one had ever seen before,” Chan said.
He added that the symptom-tracker app enabled his team “to provide critical, rapid data back to scientists, and also return it back to the public at large.”
According to Chan, a daily influx of patient data from the app made it possible to identify a cohort of individuals with “long Covid.” He added that between 15 and 30 percent of individuals with mild Covid-19 symptoms may develop this long-term condition.
Gordon said these patients can experience “fatigue, headache, brain fog, heart trouble, sleep problems” and more for weeks after their diagnosis. Chan added that the symptoms of long Covid can broadly be classed as neurological, gastrointestinal, or respiratory, suggesting there may be different “subtypes” of long Covid.
Chan and his team harnessed data from the symptom tracking app to make several observations about the demographic risks of contracting long Covid.
“If you had multiple symptoms, that put you at about a three-fold higher likelihood of getting long Covid, and we also found that people who were older were more likely to get long Covid,” Chan said. “Also, women were more likely to get long Covid.”
Chan noted the severity of initial Covid-19 symptoms seems to have little bearing on whether a patient develops long Covid, though he acknowledged the data considered could have been limited.
“Even people with relatively mild symptoms can end up with long Covid,” he said. “There's even some suggestion that people may be asymptomatic to start with, and then develop symptoms well after they recovered from the virus.”
Chan said there was initially skepticism among medical professionals about whether long Covid was “a real thing,” with experts suggesting that the long-term symptoms reported were not physical, but rather of “psychological” origin.
“The initial reluctance to embrace long Covid as a diagnosis, if you will, really came from deep-seated biases about how people should be able to recover from viral illnesses,” Chan said in an interview after the event. He credits much of the medical establishment’s recognition of long Covid to the work of patient advocacy groups.
As for treatment, Chan said the health care system will need to take a holistic approach — one that involves professionals with “different specializations and different backgrounds of expertise” and “multidisciplinary care.”
Though Chan said he is optimistic that medical experts will address long Covid “in a cohesive way,” he remains concerned about the condition’s long-term societal impacts.
“We're at a tipping point where I think we're really going to potentially see even higher reports of long Covid,” he said. “The impact of that on our workforce and our society I think will be felt for many years to come.”