• Posted November 19, 2025

Long COVID Can Take Eight Different Paths, Experts Say

Long COVID can follow one of eight different symptom paths, as patients suffer for months past their initial infection, a new study reports.

The eight identified “trajectories” show how long COVID can differ between patients based on its severity and duration, as well as whether their symptoms improve or worsen over time, researchers reported Nov. 17 in the journal Nature Communications.

“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,” lead researcher Tanayott Thaweethai, an assistant professor at Harvard Medical School and associate director of Massachusetts General Hospital Biostatistics in Boston, said in a news release.

For the study, researchers tracked nearly 3,700 adults who first contracted COVID-19 during the Omicron variant era, after December 2021.

Overall, about 10% developed long COVID symptoms three months after infection. Among these, 4 out of 5 (81%) continued to have symptoms a year later.

Among patients with long COVID, eight distinct profiles emerged. These included distinct groupings of patients whose symptoms:

• Remained high at all times.

• Fluctuated, only intermittently meeting the threshold for long COVID.

• Decreased over time.

• Started low and disappeared by 6 months.

• Increased over time.

• Started low but increased after 15 months, driven partly by an increase in post-exertional malaise.

• Remained low, with intermittent bouts that didn't meet the minimum threshold.

• Were so minimal they never met the threshold for long COVID.

These trajectories will help doctors better track the progress of patients with long COVID, researchers said.

“This study addresses an urgent need to define the differing long COVID trajectories,” senior researcher Dr. Bruce Levy, chair of medicine at Brigham and Women's Hospital in Boston, said in a news release.

“Our findings will help determine what resources are needed for clinical and public health support of individuals with long COVID and will also inform efforts to understand long COVID’s biological basis,” Levy said.

More than 200 long COVID symptoms have been identified, according to the U.S. Centers for Disease Control and Prevention (CDC).

Fatigue, brain fog and post-exertional malaise are among the most commonly reported, but others include coughing, chest pain, heart palpitations, headaches, sleep problems, lightheadedness, changes in smell and taste, diarrhea, constipation, joint or muscle pain and rashes.

More information

The U.S. Centers for Disease Control and Prevention has more about long COVID symptoms.

SOURCES: Mass General Brigham, news release, Nov. 17, 2025; Nature Communications, Nov. 17, 2025