Physical and mental characteristics after infection with COVID-19

In a recent study published in search field* Prepress server, researchers performed symptom assessment, cognitive tests, and physical measurements after infection with the coronavirus disease 2019 (COVID-19).

Study: Symptoms, physical measures, and cognitive testing after SARS-CoV-2 infection in a large population-based control study. Image Credit: Fotomay / Shutterstock

Various studies have reported severe symptoms manifested in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in-hospital patients. However, extensive research is needed to confirm post-COVID-19 symptoms in out-of-hospital patients.

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In this study, the researchers investigated disease outcomes after infection with SARS-CoV-2 in individuals with or without prior infection in a large population in Iceland.

The study included 3,602 individuals 18 years of age and older with a reported history of COVID-19 infection. Participants tested positive for SARS-CoV-2 at least five months before September 2020 or February 2021. The team also included individuals who had participated in the dHS study before the pandemic, allowing the team to make comparisons in individual characteristics before and after infection.

Individuals with previous infection were confirmed by the presence of antibodies while positive patients were identified by either quantitative polymerase chain reaction (qPCR) assays on high-risk cohorts or population screening. The control group consisted of subjects who had previously participated in the pre-pandemic deCODE Health Study (dHS) from June 2016 to March 2020, called historical controls, as well as participants in the dHS study from September 2021 to September 2021 who had no history of COVID infection -19, called contemporary controls.

The study included questionnaires regarding an individual’s health and lifestyle, along with multiple blood, physiological and cognitive tests. The team also screened for any symptoms of depression, anxiety, stress, fatigue and health anxiety by adding questionnaires including generalized anxiety disorder-7 (GAD-7), Perceived Stress Scale (PSS), Patient Health Questionnaire-9 (PHQ-9), impact questionnaire Symptoms (SIQR), and Short Health Anxiety Inventory (SHAI). Health-related quality of life was also assessed using a 36-item short survey (36-SF) and satisfaction with life scale (SWLS).

The team reported the association between history of prior COVID-19 infection and results of questionnaires (1) C19Q, GAD-7, PHQ-9, PSS, SHAI, SIQR, SWLS, and 36-SF; (2) Measurements of weight, height, body mass index, heart rate, blood pressure, body composition and oxygen saturation; (3) Cognitive tests and; (4) Blood tests.


Study results showed that the dHS included 3,602 eligible Icelanders who were infected with SARS-CoV-2. The median age of infected cases was 46 years with 51% of cases being female. Furthermore, approximately 33% of the participants were obese, 18% had asthma, and 11% were immunocompromised.

The study also included a total of 14,388 controls, including 546 contemporary participants and 13,842 historical participants. The mean age of the control group was 56 years with 57% of the group being female.

Nearly 40% of participants reported mild to severe symptoms of COVID-19 while 5% of cases required hospitalization due to the severity of COVID-19. The team noted that women and elderly participants had a higher chance of reporting severe COVID-19 infection along with individuals with obesity, asthma and other comorbidities.

Participants themselves reported that up to five to six months after infection, 33% of all cases had not fully recovered from the disease, with 5% still experiencing severe symptoms. However, 13 months after infection, 21% had not yet recovered and 1% had severe symptoms. Moreover, assessment of quality of life and mental health showed fewer symptoms of stress in the case of patients compared to the control group.

The physiological tests performed showed that symptoms associated with altered sense of taste and smell, including hypo-olfactory, partial loss of sense of smell, and partial senescence were more common by the condition patients than the control group. Furthermore, tests that evaluated smell showed higher results over time since the acute injury.

A total of 30% of cases and 15% of the control group had long-term symptoms of COVID. Case patients were 2.5 times more likely to show prolonged COVID symptoms than the control group. Furthermore, individuals with comorbidities were 3.2 times more likely to experience COVID for a prolonged period. Notably, women and individuals with more severe infections and high-risk conditions including compromised immunity, heart failure, and coronary artery disease have a higher chance of suffering from COVID for a prolonged period.


The results of the study showed that many diverse symptoms were more prevalent in patients with COVID-19 than in the control group. Researchers believe that differences between symptoms and measurements indicate response bias in self-reported symptoms while conventional tests provide a more complex response model among affected individuals.

*Important note

Research Square publishes primary scientific reports that have not been peer-reviewed, and therefore should not be considered conclusive or guide clinical practice/health-related behaviour, or treated as established information.


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