New research syntheses suggest long COVID—typically defined as symptoms lasting at least two months after SARS‑CoV‑2 infection with no alternative explanation—may be driven by overlapping processes including viral persistence, chronic inflammation and tiny blood clots. Scientists say there are still no approved, evidence-based treatments, though rehabilitation strategies and several experimental approaches, including metformin given early in infection, are under study.
Long COVID is increasingly described by researchers as a multi‑organ condition that can persist for months after an initial SARS‑CoV‑2 infection. A recent research summary published via ScienceDaily said the illness can involve the brain, heart, blood vessels and immune system, and estimated that about 65 million people worldwide are affected.
What researchers think may be driving symptoms
Scientists described several biological mechanisms that may overlap in long COVID:
- Lingering virus in the body after the acute infection.
- Ongoing low‑level inflammation, including elevated inflammatory markers such as IL‑1β, IL‑6 and TNF‑α.
- Micro‑clots (tiny blood clots) potentially linked to interactions between the virus’s spike protein and fibrinogen, which could contribute to abnormal clotting and impaired breakdown of clots.
- Additional hypotheses that continue to be investigated include autoimmunity, changes in gut bacteria (dysbiosis) and mitochondrial dysfunction.
Researchers note that these pathways could help explain a wide range of reported problems, including blood vessel dysfunction, neuro‑inflammation, ME/CFS‑like fatigue, and metabolic issues such as blood sugar dysregulation.
Care and rehabilitation
For people with milder illness, structured rehabilitation programs and pacing are commonly recommended to help manage daily activity and reduce symptom flare‑ups, according to the ScienceDaily summary. Experts generally caution that patients—especially those with post‑exertional symptom worsening—should not assume that pushing through fatigue with unsupervised exercise is safe.
Therapies under study
There is still no proven cure for long COVID, and many proposed treatments remain supported mainly by small or preliminary studies.
- Metformin during acute infection: A randomized trial (COVID‑OUT) reported that early outpatient treatment with metformin was associated with a 41.3% lower risk of a long‑COVID diagnosis over 10 months of follow‑up.
- Antivirals and long COVID risk: Evidence is mixed. Some studies have found no clear reduction in long COVID risk with nirmatrelvir/ritonavir (Paxlovid) in certain vaccinated outpatient populations, while other observational research has suggested benefits for specific symptoms or subgroups.
- Ensitrelvir: An exploratory analysis from a phase 3 trial reported numerical reductions versus placebo in the risk of persistent symptom burden at multiple follow‑up time points, but the confidence intervals were wide and crossed no effect, underscoring uncertainty.
Vaccination and long COVID
Systematic reviews and public health assessments generally find that vaccination before infection reduces—but does not eliminate—the risk of developing long COVID. Reviews have estimated an overall relative risk reduction on the order of roughly 20% to 30%, though results vary across studies and definitions, and evidence is less certain for booster‑specific effects.
What remains uncertain
Researchers emphasize that many promising ideas—ranging from anti‑inflammatory drugs and anticoagulation strategies to microbiome‑targeted approaches and other experimental therapeutics—still require large, well‑controlled clinical trials. In the meantime, clinicians typically recommend multidisciplinary care focused on symptom management, rehabilitation tailored to tolerance, and monitoring for organ‑specific complications.
