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The prevalence of long COVID symptoms among adult patients was found to be relatively high 2 years following index COVID-19 infection, with female sex, obesity, and severity of initial infection identified as predictors for the emergence of common symptom clusters. These study findings were published in the Journal of Infection.

Researchers conducted a follow-up survey of patients who participated in a population-based, longitudinal, observational study of Long COVID symptom prevalence that was conducted in southwestern Germany in 2021. The researchers aimed to describe the symptom burden and associated impairment of long COVID 2 years after index SARS-CoV-2 infection. All patients who completed the survey initially tested positive for SARS-CoV-2 between 6 and 12 months prior to study enrollment. The follow-up survey included questions about COVID-19 reinfection, vaccination history, general health and working capacity, and health-related quality of life (HRQOL). A Poisson regression model was employed for statistical analysis.

A total of 6635 patients completed the follow-up survey, of whom the mean [SD] age was 45.8 [13.4] years, and 60.9% were women. The median time between index SARS-CoV-2 infection and the first survey was 8.7 months, and the median time to the follow-up survey was 23.9 months. In regard to index infections, 76.3% of patients reported mild disease severity, 3.7% required hospital admission, and 0.9% required intensive care unit admission. Nearly half (47.5%) of the population experienced at least 1 secondary COVID-19 infection, and 86.8% had received multiple COVID-19 vaccine doses. [A] considerable portion of symptoms newly emerged, of which only few could be attributed to reported SARS-CoV-2 reinfection.

Overall, 29.9% of patients met criteria for long COVID at the time of the first survey, which increased to 31.2% at the follow-up survey. Of patients who reported long COVID symptoms on the first survey, 8.8% recovered by the follow-up survey, but 10.2% reported emerging long COVID symptoms.

Predictors of emerging long COVID included female sex, lower education level, index infection severity, smoking, obesity, and underlying comorbidities. The researchers noted no association between COVID-19 reinfection and emerging long COVID.

At the individual symptom level, only 9 of 30 symptoms assessed for the study showed a net decrease in reported frequency between the first survey and follow-up survey:

Altered taste (from 17.9% to 12.2%);
Altered smell (from 23.2% to 15.8%);
Shortness of breath (from 32.1% to 29.6%);
Chronic fatigue (from 28.1% to 26.3%); and,
Rapid physical exhaustion (from 37.7% to 35.1%).

In contrast, there was a net increase in the reported frequency of cough (from 13.3% to 24.0%) and sore throat (from 8.6% to 19.7%) over the same period.

The researchers noted that the frequency of some common symptom clusters, including fatigue, neurocognitive impairment, and chest symptoms, remained relatively stable from the first survey to the follow-up survey.

Positive predictors for the emergence of any long COVID symptom cluster were female sex (relative risk [RR] range, 1.25-1.62) and treatment required (proxy for disease severity) for the acute index infection (RR range,1.47-1.83). Positive and negative predictors for the emergence of most symptom clusters included obesity and higher education level, respectively. The only significant positive predictor for the emergence of chest symptoms was secondary COVID-19 infection.

Further analysis indicated smell and taste disorders had the highest probability (59%) of resolution within the 2 years following the index infection. In patients affected by multiple symptom clusters, the resolution of 1 symptom cluster increased the likelihood of further resolution. Patients who reported sleep disorders or symptoms of anxiety or depression exhibited the highest risk for the emergence of any symptom cluster, whereas those who reported smell and taste disorders exhibited the lowest risk.

Limitations of this study include the lack of data on infections other than COVID-19, the relatively low completion rate for the follow-up survey (61.4%), and the lack of generalizability to older and younger populations due to the focus on working-aged adults.

According to the researchers, “[A] considerable portion of symptoms newly emerged, of which only few could be attributed to reported SARS-CoV-2 reinfection.”