Outcome measures were the LC Research Index (LCRI), and the Patient-Reported Outcomes Measurement Information System Global Health Survey (PROMIS-GH). The LCRI provides a weighted composite score of 0 to 30 from the presence or absence and severity of 11 symptoms: postexertional malaise, fatigue, brain fog, dizziness, palpitations, change in smell or taste, thirst, chronic cough, chest pain, shortness of breath, and sleep apnea.
The primary study outcome was 2 consecutive visits with a LC Research Index (LCRI) score of <11.A secondary outcome was 50% reduction in LCRI from the starting visit along with patient reporting good-to-excellent quality of life (QOL) with score ≥3 on the PROMIS-GH. An additional secondary outcome was an LCRI score of 0, indicating absence of symptoms.
This investigation was conducted within the NIH-funded RECOVER-Adult (Researching COVID to ENHANCE Recovery) study that included approximately 13,000 adults with history of SARS-CoV-2 infection.From that cohort, Reeder and colleagues identified 1,019 LC patients with an LCRI of ≥11 at the 12-month visit; as well as 1,283 and 1,488 participants with LC at 18- and 24-months, respectively.
The investigators reported the likely probability of participants with LC at 12 months achieving the primary outcome of 2 consecutive visits with LCRI <11 was 36.2% (95%CI 33-39.5%) by 24 months and 50.1% (46.1-54.0) by 36 months.The median time to reach that outcome was 36 months (33- >51 months).The probability of having ≥50% decrease in LCRI along with good self-reported QOL was 40.8% (37.4-44.2) by 24 months and 56.4% (52.2-60.4) by 36 months. Complete remission of LC symptoms, with an LCRI decrease to 0, was experienced by 15% (12.6-17.6) by 24 months and 26.9% (23.3-30.5) by 36 months.
What You Need to Know
In the NIH-funded RECOVER-Adult cohort, about half (50.1%) of adults with long COVID at 12 months reached sustained symptom improvement by 36 months, with a median time to improvement of 36 months.
By 36 months, 56.4% had a 50% or greater drop in symptom scores along with good-to-excellent quality of life, and 26.9% had complete remission.
Improvement varied by main symptom: by 36 months, the adjusted chance of improving was 59.6% for people with mainly smell or taste loss, 54.6% for chronic cough, and 48.5% for brain fog.
Reeder and colleagues reported similar cumulative probabilities of improvement outcomes over time for the cohort with LC at 18 months; and "slightly smaller" for those with LC at 24 months.
Although the investigators qualify the study as "not intended to disentangle causal relationships between individual characteristics and timing of symptom improvement", they did offer several subgroup analyses.Among these, they found that those with LC at 12 months characterized predominantly by smell or taste loss had an adjusted probability of achieving the primary outcome by 36 months of 59.6% (52.7-66.5).That adjusted probability for those with LC characterized by chronic cough was 54.6% (46.3-62.8); and 48.5 (41.0-56.0) for those with LC characterized predominantly by brain fog.
"These findings provide direct evidence on prospective symptomatology relevant to persons with a history of infection experiencing likely LC at a year or more after initial infection," Reeder and colleagues report.
Reference
1. Reeder HT, Donohue SE, Martin JN, et al. Timing of Long COVID improvement in prospectively followed RECOVER-Adult participants. Ann Intern Med.2026, Epub November 3. doi:10.7326/ANNALS-25-05275.
