Virus reactivation in acute and long COVID-19

Chronic viral infections are common in humans, with many individuals harboring multiple viruses that can reactivate during times of physiological stress, including severe illness. While SARS-CoV-2 infection has been shown to reactivate chronic viruses such as Epstein–Barr virus and cytomegalovirus, the extent, timing, and impact of viral reactivation in COVID-19 are not fully understood.

Using multi-omic data from 1,154 hospitalized COVID-19 patients, researchers have identified significant reactivation of Herpesviridae and Anelloviridae during acute COVID-19, with varying temporal patterns for each virus. They also found that reactivation correlates with disease severity, immune system effects, and clinical outcomes.

Although the study does not prove causation, it emphasizes the prevalence of chronic viral reactivation during acute COVID-19 and long COVID. This finding contradicts the common belief that chronic viral reactivation mainly results from immunosuppression, demonstrating that reactivation occurs frequently in healthy individuals during severe illness and is linked to increased systemic inflammation.

The research also shows that reactivation can persist in the recovery phase and is associated with anemia in long COVID. The study provides immune, transcriptomic, and metabolomic markers of viral reactivation, which could help predict and treat acute COVID-19 and long COVID.