Loss of smell, loss of taste, dyspnea, and fatigue are the four most common symptoms that healthcare professionals in Sweden report 8 months after mild COVID-19 illness, new evidence reveals.

"We see that a substantial portion of healthcare workers suffer from long-term symptoms after mild COVID-19," senior author Charlotte ThÃ¥lin, MD, PhD, told Medscape Medical News.

"Even if you are young and previously healthy, a mild COVID-19 infection may result in long-term consequences," said ThÃ¥lin, from the department of clinical sciences at Danderyd Hospital, Karolinska Institute, Stockholm, Sweden.

This research letter "adds to the growing body of literature showing that people recovering from COVID have reported a diverse array of symptoms lasting for months after initial infection," Lekshmi Santhosh, MD, told Medscape Medical News when asked to comment.

However, "there is limited data on the long-term effects after mild COVID-19, and these studies are often hampered by selection bias and without proper control groups," Thålin said.

The current findings are part of the ongoing COMMUNITY (COVID-19 Biomarker and Immunity) study looking at long-term immunity.

Thålin, lead author Sebastian Havervall, MD, and their colleagues compared symptom reporting between 323 hospital employees who had mild COVID-19 at least 8 months earlier with 1072 employees who did not have COVID-19 throughout the study.

Notably, mild illness among previously healthy individuals may be associated with long-term persistent symptoms," Sarah Jolley, MD, a pulmonologist specializing in critical care at UCHealth University of Colorado Hospital in Aurora and director of the Post-COVID Clinic, told Medscape Medical News.

Seropositive participants were almost two times more likely to report that their long-term symptoms moderately to markedly disrupted their work life, 8% vs 4% of seronegative healthcare workers (relative risk [RR], 1.8; 95%; confidence interval [CI], 1.2 - 2.9).

Interestingly, the proportion of people with persistent symptoms might be underestimated in this research, Putrino said.

Furthermore, unlike many of the people with long-haul COVID-19 whom he treats clinically — ones who are "really struggling" — the healthcare 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.

"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.

"We're really just starting to understand the long-term effects of COVID-19," Putrino said