A German study published today in BMJ finds a considerable burden of long-COVID symptoms, especially fatigue and neurocognitive impairment ("brain fog"), at 6 to 12 months—even among young and middle-aged adults who had mild infections.
A team led by Ulm University researchers parsed responses to a mailed survey from 11,710 adults aged 18 to 65 years living in southwestern Germany who tested positive for COVID-19 from Oct 1, 2020, to Apr 1, 2021, a period dominated by the wild-type virus.
Average participant age was 44.1 years, 58.8% were women, 56.8% were employed full-time before the pandemic, 77.5% didn't require medical care for their infection, 19.0% needed outpatient care, and less than 4% were hospitalized. Pre-existing chronic conditions included musculoskeletal disorders (28.9%), cardiovascular disease (17.4%), neurologic and sensory disorders (16.2%), and respiratory illnesses (12.1%).
The survey was fielded in August and September 2021, and the average interval between the initial positive COVID-19 test and survey completion was 8.5 months.
Most at risk: Women, those who needed medical care
The researchers sorted 30 new-onset long-COVID symptoms into 13 clusters. Respondents reported fatigue (37.2%) and brain fog (31.3%), a symptom cluster that the researchers said contributed most to reduced health recovery and working capacity. Other symptoms contributing to reduced work capacity included chest symptoms (30.2%), impaired taste or smell (23.6%), and anxiety and depression (21.1%).
Assuming at least moderate impairment in activities of daily living and 80% or less recovery of general health or working capacity, the estimated rate of long-COVID was 28.5% among participants (extrapolated to 8.4% for all women and 4.6% for all men in the community, if all nonrespondents had recovered completely).
Women reported more impairment than men for most new symptoms. Relative to participants reporting one or no persistent symptoms, respondents reporting at least two symptoms were, on average, slightly older (45.4 vs 42.5 years), more often women than men (3,891 of 6,030 [64.5%] vs 2,889/5,489 [52.6%]), and more likely to be obese (1,313/5,984 [21.9%] vs 813/5,446 [14.9%] and require medical care during their infection (1,948/5,976 [32.6%] vs 622/5,445 [11.4%]).
Individual, societal implications
Impaired taste or smell had the weakest association with any other symptom cluster, while fatigue, the most prevalent symptom cluster, often co-occurred with brain fog and chest symptoms. The strongest consistent association was for receipt of outpatient or inpatient care for COVID-19 infection versus no medical care, especially for rash/abnormal sensations caused by nerve damage, chills/fever, and hair loss.
Risk factors for several symptom clusters included high body mass index and smoking.
Increasing age was a risk factor for fatigue, brain fog, and musculoskeletal pain. Brain fog had a significantly stronger effect on loss of working capacity than on loss of health, while the opposite was true for chest symptoms and impaired taste or smell, which both mainly affected general health rather than working capacity.
The researchers said the study revealed long-COVID symptom clusters with individually and societally relevant implications that also affected younger adults with mild initial infections. "Given the individual and societal burden of post-covid sequelae, the underlying biological abnormalities and causes need urgent clarification to define adequate treatment options and develop effective rehabilitation measures," they concluded.