COVID-19’s long reach: Some physical symptoms can persist up to two years post-diagnosis

By Pooja Toshniwal PahariaReviewed by Danielle Ellis, B.Sc.Oct 31 2023

In a recent study published in The Lancet Regional Health-Europe, researchers investigated the prevalence rate of physical-type symptoms by the severity of acute coronavirus disease 2019 (COVID-19) beyond two years of diagnosis.

Background

Long COVID, or post-COVID-19 condition, is a significant public health concern due to persisting physical symptoms following infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

However, evidence from extensive observational research beyond a year of COVID-19 diagnosis remains scarce since most studies include small sample sizes of specific populations followed up for less than a year post-COVID-19 diagnosis. The lack of comparisons with populations without confirmed SARS-CoV-2 infection limits the interpretability of the findings.

About the study

In the present observational study, researchers comprehensively assessed long COVID symptomatology two years post-COVID-19 diagnosis.

In total, 64,880 adults were included from four Nordic groups of the COVIDMENT Consortium [the Omtanke2020 study (18,190 Swedish individuals), the COVID-19 National Resilience Cohort (C-19 Resilience, 14,358 Icelandic individuals), the COVID-19, Mental Health and Adherence Project (MAP-19, 3,310 Norwegian individuals), and the Danish Blood Donor Study (DBDS, 29,958 individuals)] with self-documented COVID-19 symptom data between April 2020 and August 2022.

Physical symptom prevalence, measured using the Patient Health Questionnaire (PHQ-15), was compared among participants with reverse transcription-polymerase chain reaction (RT-PCR)-verified SARS-CoV-2 infection and those without, by infection severity and the time since infection diagnosis. In addition, the researchers assessed changes in symptomatology in a subgroup of adult Swedish individuals, pre- and post-infection with SARS-CoV-2.

The time since diagnosis of acute COVID-19 was the duration between the reported diagnosis date and that of data collection concerning physical symptoms, and was up to 16 months, 22 months, 27 months, and 27=4 months in the C-19 Resilience, Omtanke2020, DBDS, and MAP-19 cohorts, respectively. Acute COVID-19 severity was ascertained based on self-documented durations of hospitalization and being bedridden.

The team performed Poisson regression modeling to determine the prevalence ratios (PRs). Covariates included in the analysis were age, sex, body mass index (BMI), mean monthly household income, residency relationship status, smoking status, depression, anxiety, COVID-19-associated distress symptoms, a prior history of psychiatric disorders, and pre-existing somatic comorbidities.

To assess the impact of COVID-19 vaccination on physical symptom prevalence, the team determined PR values for the Omtanke2020 and C-19 cohorts by limiting the analysis to one- or two-dose COVID-19 vaccinees. Individuals with incomplete data on COVID-19 diagnosis and >25% missing PHQ-15 data were eliminated from the study.

Results

Individuals diagnosed with SARS-CoV-2 infection were younger, with lower body mass index, and a lower percentage of somatic comorbidities and psychiatric disorders compared to those without a COVID-19 diagnosis. Among the cohorts, MAP-19 participants were younger and more likely to be single than other cohorts.

Among individuals diagnosed with SARS-CoV-2 infection, 28% were confined to bed during acute COVID-19 (18% for one to six days, and 10% for at least seven days), and one percent were hospitalized.

Severe symptom prevalence was higher for individuals who received a COVID-19 diagnosis compared to those who did not among all cohorts: 16% versus 10% in the C-19 cohort, eight percent versus six percent in the Omtanke2020 study cohort, nine percent versus eight percent in the MAP-19 cohort, and two percent versus one percent in the DBDS cohort, with the DBDS and MAP-19 cohorts having a higher percentage of individuals with SARS-CoV-2 Omicron variant infections.

During follow-up, 35% of individuals (22,382 of 64,880) received a COVID-19 diagnosis, and compared to those who did not, had higher physical symptom prevalence by 37% [PHQ-15 scores of 15 or higher, adjusted PR of 1.4]. Symptom prevalence was linked to the severity of acute SARS-CoV-2 infection: individuals confined to bed for at least a week (10%) showed the highest symptom prevalence (PR of 2.3), whereas those never bedridden showed [a prevalence similar to those who did not receive a SARS-CoV-2 infection diagnosis (PR, 0.9).

Further, prevalence was significantly higher among those diagnosed with SARS-CoV-2 infection for eight symptoms, i.e., breathlessness, dizziness, chest pain, headaches, fatigue, sleeping difficulties, back pain, and heart racing. Since most individuals had received one or two COVID-19 vaccines, the researchers found similarly increased prevalence by limiting the analysis to COVID-19 vaccinees.

In addition, the increase in prevalence was higher among non-anxious and undepressed individuals. The pairwise assessment of 398 Omtanke2020 participants with before and after SARS-CoV-2 infection measures of physical COVID-19 symptoms (mean time interval of three months) confirmed the study results.

Conclusion

Overall, the study findings showed an increased prevalence of a few physical COVID-19 symptoms beyond two years of acute infection, especially in individuals with severe acute SARS-CoV-2 infection. The findings highlighted the long COVID constitution and the long-term health implications following recovery from acute infection for the general public.

The association of long-term severe physical symptom prevalence with acute COVID-19 severity underscores the importance of continued SARS-COV-2 surveillance and COVID-19 monitoring efforts among individuals with severe acute COVID-19.