Overview
- The Nature paper reporting the finding was published on August 5, 2026 and analyzes multi‑omic data from the IMPACC study of 1,154 unvaccinated adults hospitalized with COVID‑19 between May 2020 and March 2021.
- Investigators detected at least one reactivated chronic virus in about 48% of patients, most commonly Epstein–Barr virus, cytomegalovirus, herpes simplex and members of the Anelloviridae family.
- Different viruses followed distinct timelines and compartments with Epstein–Barr and anelloviruses rising early in blood or nasal samples and CMV and HSV appearing later mainly in respiratory samples.
- Viral reactivation correlated with higher levels of systemic inflammation and worse clinical trajectories in the hospital, including longer stays and increased risk of death in the most severe groups.
- Anelloviridae activity persisted into recovery and was associated with long‑term physical deficits but causality is not proven so authors call for mechanistic studies and clinical trials to test monitoring or antiviral approaches, noting results may not apply to vaccinated or milder cases.