Study shows for most, long-COVID symptoms persist into second year

A new study based on German long-COVID patients shows 68% experience the same symptoms in year 2 as in year 1 of the chronic condition. The study, published yesterday in PLoS Medicine, adds to the current understanding of the long-term prognosis of post-COVID-19 syndrome (PCS).

The nested population-based case-control study compared 982 people ages 18 to 65 years diagnosed as having self-assessed long COVID to 576 control patients who did not have the condition.

Study participants underwent neurocognitive, cardiopulmonary exercise, and laboratory testing an average of 9.1 months (phase 2) after initial long COVID assessment. The mean age of the patients was 48 years, and 65% were female.

Phase 1 of the study was 6 to 12 months after infection, while phase 2 was a median of 8.5 months after that (range, 3 to 14 months).

Two thirds (67.6%) of the 982 participants with PCS in phase 1 were considered to have persistent PCS (according to the authors’ working definition) after the phase 2 clinical assessment, the authors said. Most of the 32% of long-COVID patients who reported an improvement at follow-up during phase 2 did not fully recover.

Exercise intolerance common

During the tests, post-exertional malaise, or exercise intolerance, was seen in 35.6% of participants with long COVID. Symptoms compatible with myalgic encephalomyelitis/chronic fatigue syndrome were seen in 11.6% of persistent PCS patients.

During exercise tests, people with long COVID had significant reductions in handgrip strength, maximal oxygen consumption, and ventilatory efficiency (how well the body exchanges oxygen). Almost half of the long-COVID patients reported breathlessness as a moderate-to-severe symptom.

In the majority of patients, PCS symptoms did not improve in the second year of their illness.

“In the majority of patients, PCS symptoms did not improve in the second year of their illness and typically continued to include fatigue and measurable exercise intolerance and cognition deficits, but there seems to be no major pathology in laboratory investigations,” the authors wrote. 

Patients with persistent PCS were less frequently never smokers (61.2% versus 75.7%), more often obese (30.2% versus 12.4%) with higher mean values for body mass index and body fat, and had lower educational status (university entrance qualification 38.7% versus 61.5%), according to the authors.

“The results call for the inclusion of cognitive and exercise testing in the clinical evaluation and monitoring of patients with suspected PCS,” the authors concluded. 

Long COVID signature identified by AI 

In other long-COVID news, artificial intelligence may be able to detect a “long COVID molecular signature” in the blood of patients, according to a study based on samples taken from a cohort of Italian children. 

The study was published today in Pediatric Research and is based on samples taken from 112 children ages 0 to 19 years. Among them, 34 had a clinical diagnosis of long COVID, 32 had an active infection at the time of the study, 27 had multisystem inflammatory syndrome (MIS-C), and 19 served as healthy controls.

An artificial intelligence model based on protein profiling was able to identify long COVID with an accuracy of 0.93, a specificity of 0.86, and a sensitivity of 0.97, the authors said. 

The findings could be the basis of diagnostic tests for long COVID. Moreover, they suggest that pediatric long-COVID patients have the same pro-inflammatory blood markers seen in adult patients.