Eight months after mild COVID-19, one in ten people still has at least one moderate to severe symptom that is perceived as having a negative impact on their work, social or home life. The most common long-term symptoms are a loss of smell and taste and fatigue. This is according to a study conducted by researchers at Danderyd Hospital and Karolinska Institutet in Sweden.
Since spring 2020, researchers at Danderyd Hospital and Karolinska Institutet have conducted the so-called COMMUNITY study, with the main purpose of examining immunity after COVID-19. In the first phase of the study in spring 2020, blood samples were collected from 2,149 employees at Danderyd Hospital, of whom about 19% had antibodies against SARS-CoV-2. Blood samples have since then been collected every four months, and study participants have responded to questionnaires regarding long-term symptoms and their impact on the quality of life.
In the third follow-up in January 2021, the research team examined self-reported presence of long-term symptoms and their impact on work, social and home life for participants who had had mild COVID-19 at least eight months earlier. This group consisted of 323 healthcare workers (83%, median age 43 years) and was compared with 1,072 healthcare workers (86% women, median age 47 years) who did not have COVID-19 throughout the study period.
The results show that 26% of those who had COVID-19 previously, compared to 9% in the control group, had at least one moderate to severe symptom that lasted more than two months and that 11%, compared to 2% in the control group, had a minimum of one symptom with negative impact on work, social or home life that lasted at least eight months. The most common long-term symptoms were loss of smell and taste, fatigue, and respiratory problems.
"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 Dr Charlotte Thålin, specialist physician and lead researcher for the COMMUNITY study at Danderyd Hospital and Karolinska Institutet.
"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," says Dr Sebastian Havervall, deputy chief physician at Danderyd Hospital and PhD student in the project at Karolinska Institutet.
The COMMUNITY study will now continue, with the next follow-up taking place in May when a large proportion of study participants are expected to be vaccinated. In addition to monitoring immunity and the occurrence of re-infection, several projects regarding post- COVID are planned.
"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," says Thålin.
Study details
Symptoms and Functional Impairment Assessed 8 Months After Mild COVID-19 Among Health Care Workers
Sebastian Havervall, Axel Rosell, Mia Phillipson, Sara M. Mangsbo, Peter Nilsson, Sophia Hober, Charlotte Thålin
Published in JAMA on 7 April 2021
Abstract
Introduction
Approximately 80% of hospitalized patients with COVID-19 report persistent symptoms several months after infection onset.1,2 However, knowledge of long-term outcomes among individuals with mild COVID-19 is scarce, and prevalence data are hampered by selection bias and suboptimal control groups.3,4 This cohort study investigated COVID-19–related long-term symptoms in health care professionals.
Methods
The COMMUNITY (COVID-19 Biomarker and Immunity) study investigates long-term immunity after mild COVID-195 (eMethods in the Supplement). Between April 15, 2020, and May 8, 2020, health care professionals at Danderyd Hospital, Stockholm, Sweden, were invited to participate, with a limit of approximately 2000 participants because of testing restrictions. Participants had blood sampling performed every 4 months. Demographics, symptoms and severity (mild or severe), and chronic diseases were obtained through questionnaires at baseline. Participants who were seropositive for SARS-CoV-2 anti–spike IgG at baseline and who reported severe symptoms were excluded, as were initially seronegative participants who seroconverted during follow-up. At the 8-month follow-up (January 11-29, 2021), participants reported via smartphone app the presence, duration (<2 months, ≥2 months, ≥4 months, ≥8 months), and severity (mild, moderate, or severe) of 23 predefined symptoms. For participants reporting at least 1 symptom persistent for at least 2 months, the Sheehan Disability Scale6 was used to score functional impairment from present or prior long-term symptoms (0, not at all; 1-3, mild; 4-6, moderate; and 7-10, marked) in 3 interrelated domains (work, social, and home life). Associations between categorical variables were assessed using the χ2 test of independence. Risk ratios (RRs) and their corresponding 95% CIs were calculated comparing seropositive and seronegative participants for moderate to severe symptoms lasting 2 or more or 8 or more months and for moderate to marked disruption on the Sheehan Disability Scale, using the STATA command cs. Statistical analyses were performed using STATA, version 16.1 (StataCorp LP). A 2-sided P value <.05 was considered statistically significant. The study was approved by the Swedish Ethical Review Authority, and informed written consent was obtained from all participants.
Results
Participant enrollment was closed after 2149 of 4375 health care professionals (49%) enrolled; 393 were seropositive. Fifty seropositive participants with severe symptoms and 404 seronegative participants who seroconverted were excluded. Twenty seropositive and 280 seronegative participants did not complete the 8-month follow-up, leaving 323 (94%) seropositive and 1072 (84%) seronegative participants. Seropositive participants who reported no or mild prior symptoms had a median (interquartile range) age of 43 (33-52) years and 268 (83%) were women; continuously seronegative participants had a median (interquartile range) age of 47 (36-56) years and 925 (86%) were women. Underlying chronic disease was reported by 71 (22%) seropositive participants vs 254 (24%) seronegative participants.
Comparing seropositive vs seronegative participants, 26% vs 9% reported at least 1 moderate to severe symptom lasting for at least 2 months (RR, 2.9 [95% CI, 2.2-3.8]) and 15% vs 3% reported at least 1 moderate to severe symptom lasting for at least 8 months (RR, 4.4 [95% CI, 2.9-6.7]) (Table). The most common moderate to severe symptoms lasting for at least 2 months in the seropositive group were anosmia, fatigue, ageusia, and dyspnea.
Of the seropositive participants, 8% reported that their long-term symptoms moderately to markedly disrupted their work life, compared with 4% of the seronegative participants (RR, 1.8 [95% CI, 1.2-2.9]); 15% reported their long-term symptoms moderately to markedly disrupted their social life, compared with 6% of the seronegative participants (RR, 2.5 [95% CI, 1.8-3.6]); and 12% reported that their long-term symptoms moderately to markedly disrupted their home life, compared with 5% of the seronegative participants (RR, 2.3 [95% CI, 1.6-3.4]) (Figure). Furthermore, 11% of the seropositive participants reported moderate to marked disruption in any Sheehan Disability Scale category as well as having at least 1 moderate to severe symptom lasting for at least 8 months, compared with 2% of the seronegative participants (RR, 4.5 [95% CI, 2.7-7.3]).
Discussion
The results of this study showed that a considerable portion of low-risk individuals with mild COVID-19 reported a diversity of long-term symptoms, and that these symptoms disrupted work, social, and home life. Limitations of the study include the possibility of recall bias and the subjective rating of symptoms. Further research is needed to understand the mechanisms underlying COVID-19–related long-term sequalae.
Karolinska Institutet material
JAMA study (Restricted access)
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