Long COVID recovery varies sharply by symptoms, study finds

People whose long COVID affects multiple body systems are far less likely to improve than overall recovery estimates suggest, with fewer than one in five experiencing sustained improvement within three years of infection, according to a U.S. study.

Researchers followed 1,019 adults who still had probable long COVID a year after their initial infection. About half experienced sustained symptom improvement over the following three years, while roughly a quarter had complete symptom remission, the study, published Monday in Annals of Internal Medicine, found.

But outcomes differed dramatically depending on the pattern of illness. About 60% of people whose long COVID was dominated by changes in smell or taste had improved by three years, compared with less than 19% of those with symptoms affecting multiple body systems.

Long COVID can cause fatigue, cognitive impairment and post-exertional malaise — a worsening of symptoms after even modest physical or mental activity — along with problems involving numerous organ systems. There is no approved treatment for the condition.

The study, part of the U.S. National Institutes of Health-funded Recover initiative, tracked symptoms including fatigue, brain fog, dizziness, palpitations, shortness of breath and changes in smell or taste. Participants were considered to have improved when their symptom score remained below the threshold for likely long COVID at two successive study visits.

But the scoring system gives substantial weight to loss of smell or taste and chronic cough, said Ziyad Al-Aly, director of the Clinical Epidemiology Center at the VA St. Louis Health Care System, who wasn’t involved in the research. Although characteristic of COVID-19 infection, those symptoms aren’t central features of the chronic multisystem illness he associates with long COVID.

The multisystem group “is a different disease altogether,” Al-Aly said. “This is the real long COVID that will endure, and these patients do not appear to show a robust trajectory of recovery.”

The findings also illustrate a broader problem in determining how many people recover from long COVID: What counts as recovery.

The symptom index used in the study was developed using data from the Recover initiative and hasn’t been independently validated in other populations, said Nisreen Alwan, a professor of public health at the University of Southampton.

Long COVID symptoms can also fluctuate, with periods of improvement followed by relapse. Alwan and a colleague argued in the BMJ in June that inconsistent definitions make it difficult to distinguish lasting recovery from temporary remission.