WEDNESDAY, Nov. 26, 2025 (HealthDay News) -- Trajectories of long COVID have been identified, according to a study published online Nov. 17 in Nature Communications.Tanayott Thaweethai, Ph.D., from Massachusetts General Hospital Biostatistics in Boston, and colleagues prospectively determined long COVID trajectories among 3,659 participants in the National Institutes of Health Researching COVID to Enhance Recovery Adult Cohort. Distinct longitudinal profiles were identified based on a long COVID research index, measured three to 15 months after infection.The researchers identified eight longitudinal profiles. Overall, 5, 12, and 14 percent had persistently high long COVID symptom burden; had nonresolving, intermittently high symptom burden; and did not meet criteria for long COVID-19 at three months, but had increasing symptoms by 15 months, respectively. Ten percent of participants met the research index threshold for long COVID at three months; of these, 46, 35, and 19 percent had persistent long COVID, had moderate symptoms, and appeared to recover, respectively."The variability we identified will enable future studies to evaluate risk factors and biomarkers that could explain why patients vary in time of recovery, and help identify potential therapeutic targets," Thaweethai said in a statement.Several authors disclosed ties to the biopharmaceutical industry.Abstract/Full Text.Sign up for our weekly HealthDay newsletter