Symptoms of COVID-19 Can Last at Least 8 Months Even in Some Mild Cases

About 15% of health care workers who experienced mild COVID-19 reported at least one ongoing symptom at least 8 months after infection, according to a new study in Sweden.

The research letter, published in JAMA, detailed the ongoing COVID-19 Biomarker and Immunity study (COMMUNITY), including 323 seropositive and 1072 seronegative participants enrolled between April 15 and May 8 at Danderyd Hospital in Stockholm. Blood samples were evaluated every 4 months and participants responded to questionnaires.

“We see that a substantial portion of healthcare workers suffer from long-term symptoms after mild COVID-19,” corresponding author Charlotte Thalin, MD, PhD, of Danderyd Hospital and Karolinska Institute told Contagion. “The most commonly reported long-term symptoms were loss of smell and fatigue, symptoms which may seem trivial, but have a negative impact on work, social and home life in the long run. There are many reasons for controlling the spread of COVID-19, and this is one reason. Even if you are young and previously healthy, a mild COVID-19 infection may result in long-term consequences.”

About 26% of seropositive participants reported at least 1 moderate to severe symptom for at least 2 months, and 15% reported at least 1 moderate to severe symptoms for at least 8 months, compared with 9% and 3% of seronegative participants respectively.

About 8% of seropositive participants reported moderate to marked disruption of work life because of their symptoms, compared with 4% of seronegative participants. Moderate to marked disruptions to social life were reported among 15% of seropositive and 6% of seronegative participants, and disruptions to home life were reported among 12% and 5% respectively.

“Long-term symptoms are well-documented in severely ill and hospitalized COVID-19 patients,” Thalin said. “Data is however limited on the long-term effects of mild COVID-19 disease. I did not expect to see such a large portion of study participants reporting symptoms over as long as eight months after mild COVID-19.”

Most participants were considered low risk, with a median age of 43 among the seropositive group and 47 for the seronegative group with underlying chronic disease reported by 22% and 24% respectively.

About 11% of seropositive participants reported both disruption in any Sheehan Disability Scale category and at least 1 symptom lasting for at least 8 months.

“I think our data emphasizes the importance of adequate PPE and a wider implementation of RT-PCR screening in both healthcare workers and patients in healthcare settings to protect healthcare workers,” Thalin said. “Even mild COVID-19 infection can result in long-term symptoms hampering everyday life. However, it is noteworthy that we did not find an increased prevalence of other organ-specific long-term symptoms such as heart palpitations and neurological deficits such as concentration and memory impairment following mild COVID-19 in our study. Hopefully these type of long-term effects may affect primarily severely ill and hospitalized COVID-19 patients.”

Long-term effects of COVID-19 have been a topic of interest as the pandemic has progressed. One recent study showed that half of COVID-19 patients hospitalized in France reported symptoms, including fatigue, cognitive problems and dyspnea, 4 months after hospitalization. An earlier study in China found that more than three-quarters of hospitalized patients reported at least 1 symptom 6 months after infection. A small study from the University of Washington that included outpatients found that about a third of patients reported persistent symptoms an average of 6 months after the onset of COVID-19.

The COMMUNITY study is ongoing, with the next follow-up scheduled for May.

“The primary aim of the COMMUNITY study is to investigate long-term immunity after COVID-19 and vaccination, but we will also look into the prognosis of and possible underlying pathophysiological mechanisms behind COVID-19-related long-term symptoms, such as loss of taste and smell,” Thalin said.