Mild COVID-19 infections leave long-lasting symptoms up to 8 months

SOLNA, Sweden — Around 10 percent of patients with a mild COVID-19 infection still suffer at least one moderate to severe symptom eight months later, according to a recent study. Researchers from Sweden’s Danderyd Hospital and Karolinska Institute say the most prevalent long-term symptoms include a loss of smell or taste and exhaustion. Moreover, the team notes these symptoms have a detrimental influence on professional, social, and family life.

The researchers began conducting the “COMMUNITY” study in spring 2020 with the goal of evaluating immunity following COVID-19. They obtained samples of blood from 2,149 Danderyd Hospital workers during the first course of the experiment in spring 2020, with around 19 percent of them having antibodies towards SARS-CoV-2. Since then, they have obtained blood samples every four months, and volunteers have completed questionnaires about lasting symptoms and their effect on well-being.

The study team looked at symptoms that remained and their influence on professional, social, and family life for people who had reported having mild COVID-19 at least eight months previously. This occurred during the third follow-up period in January 2021, during which time 323 healthcare professionals (83% women, average age 43 years-old) were compared to 1,072 other healthcare professionals (86% women, average age 47) who had not had COVID-19 during the trial period.

Long COVID can be disruptive for nearly a year

According to the findings, 26 percent of those who previously had COVID-19 had at least one moderate to severe symptom remaining after two months. Only nine percent of the control group had symptoms. Additionally, 11 percent had at least one symptom lasting longer than eight months that negatively affected their professional, social, or family life, compared to just two percent of the control group. Long-term effects included respiratory issues, loss of smell and taste, and exhaustion.

“We investigated the presence of long-term symptoms after mild COVID-19 in a relatively young and healthy group of working individuals, and we found that the predominant long-term symptoms are loss of smell and taste. Fatigue and respiratory problems are also more common among participants who have had COVID-19 but do not occur to the same extent,” says Charlotte Thålin, specialist physician, Ph.D. and lead researcher for the COMMUNITY study at Danderyd Hospital and Karolinska Institute, in a media release. “However, we do not see an increased prevalence of cognitive symptoms such as brain fatigue, memory and concentration problems or physical disorders such as muscle and joint pain, heart palpitations or long-term fever.”

“Despite the fact that the study participants had a mild COVID-19 infection, a relatively large proportion report long-term symptoms with an impact on quality of life. In light of this, we believe that young and healthy individuals, as well as other groups in society, should have great respect for the virus that seems to be able to significantly impair quality of life, even for a long time after the infection,” adds Sebastian Havervall, deputy chief physician at Danderyd Hospital and Ph.D. student in the project at Karolinska Institute.

Can getting the vaccine help?

The last follow-up occurred in May 2021 which included many vaccinated participants. The team plans to continue monitoring immunity and re-infections after COVID-19.

“We will, among other things, be studying COVID-19-associated loss of smell and taste more closely, and investigate whether the immune system, including autoimmunity, plays a role in post-COVID,” Thålin concludes.

The team published their findings in the journal JAMA.

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