Key findings on functioning
At 8 months, using a smartphone app, participants reported presence, duration, and severity of 23 predefined symptoms. Researchers used the Sheehan Disability Scale to gauge functional impairment.
A total of 11% participants reported at least one symptom that negatively affected work or social or home life at 8 months versus only 2% of the control group.
Seropositive participants were almost two times more likely to report that their long-term symptoms moderately to markedly disrupted their work life, 8% versus 4% of seronegative healthcare workers (relative risk, 1.8; 95%; confidence interval, 1.2-2.9).
Disruptions to a social life from long-term symptoms were 2.5 times more likely in the seropositive group. A total 15% of this cohort reported moderate to marked effects, compared with 6% of the seronegative group (RR, 2.5; 95% CI, 1.8-3.6).
The researchers also inquired about home life disruptions, which were reported by 12% of the seropositive health care workers and 5% of the seronegative participants (RR, 2.3; 95% CI, 1.6-3.4).
The study’s findings “tracks with a lot of the other work we’re seeing,” David Putrino, PT, PhD, director of rehabilitation innovation at Mount Sinai Health System in New York, said in an interview. He and his colleagues are responsible for managing the rehabilitation of patients with long COVID.
Interestingly, the proportion of people with persistent symptoms might be underestimated in this research, Dr. Putrino said. “Antibodies are not an entirely reliable biomarker. So what the researchers are using here is the most conservative measure of who may have had the virus.”
Potential recall bias and the subjective rating of symptoms were possible limitations of the study.
When asked to speculate why researchers did not find higher levels of cognitive dysfunction, Dr. Putrino said that self-reports are generally less reliable than measures like the Montreal Cognitive Assessment for detecting cognitive impairment.
Furthermore, unlike many of the people with long-haul COVID-19 whom he treats clinically – ones who are “really struggling” – the health care workers studied in Sweden are functioning well enough to perform their duties at the hospital, so the study population may not represent the population at large.
More research required
“More research needs to be conducted to investigate the mechanisms underlying these persistent symptoms, and several centers, including UCSF, are conducting research into why this might be,” Dr. Santhosh said.
Dr. Thålin and colleagues plan to continue following participants. “The primary aim of the COMMUNITY study is to investigate long-term immunity after COVID-19, but we will also look into possible underlying pathophysiological mechanisms behind COVID-19–related long-term symptoms,” she said.
“I hope to see that taste and smell will return,” Dr. Thålin added.
“We’re really just starting to understand the long-term effects of COVID-19,” Putrino said. “This is something we’re going to see a lot of moving forward.”
Dr. Thålin, Dr. Santhosh, Dr. Jolley, and Dr. Putrino disclosed no relevant financial relationships. The research was funded by grants from the Knut and Alice Wallenberg Foundation, Jonas and Christina af Jochnick Foundation, Leif Lundblad Family Foundation, Region Stockholm, and Erling-Persson Family Foundation.
A version of this article first appeared on Medscape.com.