Study Identifies Diverse Long-COVID Trajectories

A significant study from the US has highlighted eight unique trajectories for long COVID, shedding light on the varied experiences of this condition. This research provides a foundation for upcoming studies aimed at examining risk factors and biomarkers that might clarify differences in symptoms and point to potential treatment targets.

Conducted by a team at Massachusetts General Hospital, the study monitored 3,659 participants, predominantly female (69%), from the NIH-supported RECOVER Adult Cohort. RECOVER was initiated by the National Institutes of Health to treat COVID as a major global health concern.

Researchers tracked individuals from three to fifteen months following their initial COVID infection, with nearly all (99.6%) participants infected with the Omicron variant. The enrollment period lasted from October 29, 2021, to June 27, 2023.

Overall, 10.3% of participants qualified for long COVID at three months, with 81% reporting ongoing or fluctuating symptoms well over a year later.

The findings were recently published in Nature Communications.

Worsening Symptoms in 14% of Participants

The study uncovered eight different symptom trajectories. Approximately 5% of those infected experienced a “persistent, high” symptom burden for the full 15 months, while 12% had “intermittently high” symptoms. Another 10% reported moderate symptoms that gradually improved, and 9% showed low-level symptoms that largely disappeared by the sixth month.

Interestingly, 14% of participants experienced either worsening symptoms or a delay in symptom improvement, including a subset whose symptoms stayed minimal until a sudden spike at the 15-month mark.

Comparisons with an uninfected group during the same timeframe indicated that while persistent and improved symptoms were less common in uninfected individuals, some patterns of worsening were evident in both groups. This suggests that not every increase in symptoms aligns with long COVID.

The authors acknowledged limitations in the study, such as the dependence on symptom surveys taken every three months, which might have overlooked finer daily changes, and the inability to track symptoms beyond 15 months. Nevertheless, the large sample size, diverse population, thorough symptom questionnaires, standardized long-COVID index, and minimal dropout rate offer a clearer understanding of the varying trajectories of long COVID.

In a press release from Mass General Brigham, Richard Levy, MD, who is part of the MGB Department of Medicine, noted, “Our findings will help identify what resources are necessary for clinical and public health support for those with long COVID, and they will also aid in efforts to comprehend the biological basis of long COVID.”