One of the largest studies of Long-COVID yet conducted reveals that more than a third of people who test positive for the virus have at least one symptom three to six months later. Symptoms are 50 percent more common than for people recovering from even serious bouts of Influenza.
Almost since the pandemic started anecdotal reports have appeared of people who survived, but suffered unexpectedly lingering effects. These accounts came not only from those who needed to be hospitalized but from people whose lives never appeared in danger and in some cases were not all that sick.
With time we've advanced to scientific studies, but most of these have either been small or used self-selecting samples. Now a paper in PLOS Medicine provides a much more rigorous picture. Unfortunately, it is just as disturbing as the earlier work.
Dr Max Taquet of the University of Oxford and co-authors looked at the anonymized electronic health records of 273,618 American COVID-19 survivors. Of these, 57 percent reported one or more symptoms associated with Long-COVID in the six months after infection. It's hardly surprising more than half the people with COVID didn't recover instantly, but when the authors focused only on health records for the period three to six months after testing positive they still found 36.6 percent had reported at least one symptom.
All the symptoms the authors investigated could have causes other than SARS CoV-2 infection. Indeed the most common, Anxiety or Depression (15 percent), could easily reflect the state of the world rather than personally catching the virus.
However, other unusually common symptoms include abnormal breathing (8 percent) and chest/throat pain (6 percent). Across the board, symptoms were 44-104 percent higher than among those who never caught the disease.
At first sight, the rates of fatigue (6 percent) and headache (5 percent) reported in the study look low, but these are cases severe enough to make it onto health records.
“The results confirm that a significant proportion of people, of all ages, can be affected by a range of symptoms and difficulties in the six months after COVID-19 infection,” Taquet said in a statement. “These data complement findings from self-report surveys, and show that clinicians are diagnosing patients with these symptoms. We need appropriately configured services to deal with the current and future clinical need.”
Predictably, people who suffered more severe attacks were also more likely to experience lingering symptoms, but the difference Taquet and co-authors found is not as sharp as might be expected. Even people who skated through relatively unscathed can be sicker months later than those who were in hospital.
Inevitably age is a risk factor. Women were also slightly more likely to be diagnosed with Long-COVID symptoms than men, but the paper also finds differences in symptom frequency by sex and age. Men, particularly older ones, more often reported breathing difficulties and “brain fog”, while younger women were more likely to have headaches and anxiety.
Perhaps the most disturbing finding is that 40 percent of Long-COVID sufferers experienced symptoms after the three-month mark they had not reported during the first recovery period.
“Research of different kinds is urgently needed to understand why not everyone recovers rapidly and fully from COVID-19,” said senior author Professor Paul Harrison.