R3 Seminar Recap: Long COVID trajectories in adults
RECOVER researchers share findings from a recent study on how Long COVID presents and progresses in adults, setting a new foundation for future research and clinical trials.
During the February 10, 2026, RECOVER Research Review (R3) Seminar, RECOVER researchers Sarah Donohue, PhD, MPH, and Tanayott (Tony) Thaweethai, PhD, presented research on Long COVID trajectories in adults. Published in November 2025, this research—which includes participants from the initiative’s adult observational cohort study—explores different clinical presentations of Long COVID and how the condition progresses over time. RECOVER Patient Representative and co-author Mady Hornig, MD, MA, and Timothy Henrich, MD, MMSc, a Long COVID researcher, also shared their perspectives and experiences.
Watch the R3 recording below or on YouTube
Working on the Long COVID puzzle
With over 200 unique symptoms, Long COVID can look different for everyone. The condition can also progress differently in each person over time. These different trajectories—presentations and progressions of Long COVID—can depend on the types of symptoms a person experiences, how long these symptoms last, how severe they are, and whether a person has pre-existing health conditions.
Dr. Donohue (University of Illinois College of Medicine Peoria; ILLInet) sees the study of Long COVID trajectories as a foundation for researchers to begin categorizing (describing) the long-term health experiences of adults with Long COVID. Understanding these different trajectories can inform how doctors diagnose and recognize Long COVID and care for patients with the condition over time.
“If you think of Long COVID as a giant thousand-piece puzzle, we’ve now flipped all the puzzle pieces over [with this study] and we’ve started to work on the edges,” said Dr. Henrich (University of California, San Francisco). “We just need to put those pieces in their final position.”
Placing the first puzzle pieces
The study included 3,659 adult study participants with a SARS-CoV-2 infection (the virus that causes COVID-19) between October 2021 to June 2023 from 86 RECOVER study sites across the United States. Dr. Donohue, Dr. Thaweethai (Massachusetts General Hospital; Harvard Medical School), and the study team set out to characterize (describe) Long COVID trajectories over 15 months.
Researchers used the Long COVID research index (LCRI), previously developed through a RECOVER study, and severity measures from symptoms surveys to determine overall symptom burden (the impact Long COVID symptoms have on a person’s life) at 3-month intervals. The index uses a point system, where points are assigned to various Long COVID symptoms. A score of 11 or higher may indicate a person has the condition.
Eight clear profiles of Long COVID trajectories emerged from the study:
- Profile A: Persistent, high symptom burden. These patients met the threshold for Long COVID (as defined by the LCRI) across all visits.
- Profile B: Intermittently high symptom burden. These participants met the threshold for Long COVID (as defined by the LCRI) on some visits but not all visits.
- Profile C: Improving, moderate symptom burden. This described participants whose LCRI decreased over time.
- Profile D: Improving, low symptom burden. This profile described participants whose LCRI was on average lower than profile C and decreased over time.
- Profile E: Worsening, moderate symptom burden. This group described participants whose LCRI gradually increased over time.
- Profile F: Delayed worsening symptom burden. This profile described participants whose LCRI was very low at the start and middle of the study, but increased at the end of the study.
- Profile G: Consistent low symptom burden. This described participants who have generally low LCRI, with some off and on symptoms that usually did not reach the Long COVID threshold (as defined by the LCRI).
- Profile H: Consistent minimal to no symptom burden. This group described participants who never met the threshold for Long COVID (as defined by the LCRI).
Some participants had persistent Long COVID symptoms, whereas other participants showed improved or worsened symptoms over the course of the study. Participants who experienced a persistent, high symptom burden (Profile A) compared with those who experienced a consistent, minimal to no symptom burden (Profile H) were:
- More often female (77% vs. 64%)
- More likely to have been hospitalized during the acute phase (when a person first experiences symptoms) of their first SARS-CoV-2 infection (6% vs. 1%)
For participants who experienced a worsening of symptoms over time, the study also found that reinfection did not seem to be a key driver of worsening Long COVID symptoms. Although 14% of study participants’ symptoms worsened over time, represented by Profiles E and F, SARS-CoV-2 reinfection rates were not much higher for this group. This suggests that factors other than reinfection explained the increase in index score.
The study also validated that Long COVID can be experienced differently among individuals even 3 months after having COVID. Participants can have different symptoms, a different number of symptoms, or different rates of improvement. 10.3% of study participants met the symptom criteria for Long COVID at 3 months, of which:
- 46% experienced persistent, high symptom burden
- 35% experienced intermittently high symptom burden
- 18% experienced improving, moderate symptom burden
The panelists highlighted that the different Long COVID trajectories emerging from the study’s findings can inform enrollment criteria in future Long COVID studies and clinical trials. Research that focuses on individual symptoms, rather than an index of symptoms, will help clarify how these individual symptoms evolve over time and contribute to Long COVID symptom burden.
Understanding the emerging picture
Dr. Henrich acknowledged that there are many myths about Long COVID and added that this research will help move doctors and other healthcare providers toward a better understanding of the condition. This understanding can also help create a framework for more comprehensive Long COVID care.
For people with Long COVID, Dr. Hornig hopes that this study will help researchers better understand how to predict patients’ health and improve collaboration between patients and healthcare providers on Long COVID care. This research can reinforce for healthcare providers that Long COVID symptoms and treatments can be unique to each patient, requiring tailored treatment plans.
Dr. Thaweethai explained that studying Long COVID trajectories can help identify risk factors and biomarkers (signs of disease that can be observed and measured), which will help researchers understand why some people recover from the condition and others do not. These findings can also inform future RECOVER clinical trials.
Because many people with Long COVID experience persistent symptoms over several years, Dr. Thaweethai is interested in examining Long COVID symptoms beyond the 15-month study period. He also noted that studies of children and how Long COVID varies based on developmental stages will also help improve understanding of Long COVID across the lifespan.
The panelists expressed their deep gratitude for RECOVER study participants and Representatives, noting that their voices and perspectives are crucial in continuing to solve the puzzle of Long COVID. “It’s the collective work of people with all types of backgrounds working on this problem to find all the pieces that fit together,” Dr. Thaweethai shared.
To find recordings and transcripts of from previous R3 Seminars, visit the R3 Seminar Series webpage or the RECOVER YouTube channel.