Nationwide study reveals many Long COVID patients still exhibit symptoms three years post-infection

Just how long is Long COVID? Though millions of patients have developed this chronic SARS-CoV-2-associated condition since the pandemic first hit, there is limited clinical data on symptom improvement and resolution over time.

Addressing this unmet need is the ongoing, prospective NIH Researching COVID to Enhance Recovery (RECOVER) Initiative’s observational study, consisting of over 13,000 adults around the United States with a history of SARS-CoV-2 infection. A sub-cohort of RECOVER adult study participants with likely Long COVID contributed to a recent investigation led by Harrison Reeder, PhD, of Mass General Brigham, and jointly supervised by Andrea Foulkes, ScD, of Mass General Brigham and the Harvard T. H. Chan School of Public Health; Leora Horwitz, MD, MHS, of the NYU Grossman School of Medicine; and Bruce Levy, MD, of the Washington University School of Medicine.

Participants completed surveys every three months assessing key Long COVID symptoms like brain fog, change in smell or taste, and palpitations. The data were then used to compute scores using a Long COVID research index for defining and evaluating symptom improvements, including sustained symptom reduction across consecutive surveys and remission of all index-defining symptoms. When analyzing data, the researchers used a statistical “time-to-event” approach to estimate how long it took for symptoms to improve, rather than simply measuring them at a single time point.

The study found that among individuals with likely Long COVID one year after initial SARS-CoV-2 infection, approximately half experienced a sustained reduction in symptoms within the following two years, while only a quarter experienced a complete remission.

These findings are critical for understanding the progression of Long COVID. While the results demonstrate the potential for natural symptom resolution within three years of infection, the persistence of symptoms in many people emphasizes the need for further Long COVID research using placebo-controlled therapeutic trials.

Published in Annals of Internal Medicine on November 3, 2026 | Read the paper: “Timing of Long COVID improvement in prospectively followed RECOVER-Adult participants”

Summary reviewed by: Harrison Reeder, PhD, lead author