Health: A new study has found that severe COVID-19 may reactivate viruses that have remained dormant in the body after earlier infections, offering new clues about why some patients experience severe illness and persistent symptoms after recovering from COVID-19.
Researchers analyzed biological data from 1,154 hospitalized COVID-19 patients participating in the Immunophenotyping Assessment in a COVID-19 Cohort (IMPACC) study. They examined multiple types of biological information to determine whether viruses already present in patients became active during COVID-19.
The researchers detected reactivation involving viruses from several families, including Herpesviridae, Enteroviridae and Anelloviridae, particularly during the first 40 days following hospital admission. Among the viruses observed were Epstein-Barr virus (EBV) and cytomegalovirus (CMV), which can remain in the body in a latent state following earlier infections.
Most people carry some viruses that remain largely inactive for long periods. These viruses can normally be controlled by the immune system. However, a serious illness can place significant stress on the body’s immune and inflammatory systems, potentially allowing some previously controlled viruses to become active again.
The study found that viral reactivation was associated with the severity of COVID-19 and several clinical outcomes. Researchers also observed that persistent reactivation of Anelloviridae during recovery was associated with post-acute COVID-19 symptoms, particularly problems involving physical function and fatigue.
The findings could help explain why some people continue to experience symptoms long after the initial SARS-CoV-2 infection has ended. Long COVID can involve prolonged fatigue, reduced physical ability and other symptoms, and researchers have been investigating whether immune disturbances and reactivation of existing viruses contribute to these conditions.
However, scientists caution that the study does not prove that reactivated viruses directly cause Long COVID. The relationship is more complicated, and researchers are still investigating whether viral reactivation contributes to symptoms, results from severe illness, or reflects other changes occurring in the immune system.
The research also suggests that COVID-19 may affect the body beyond the direct effects of SARS-CoV-2. Researchers identified changes involving inflammatory molecules, immune cells and other biological processes alongside viral reactivation. These findings provide a broader picture of how severe COVID-19 can influence the body’s existing viral landscape.
EBV is particularly important because it is extremely common and usually remains dormant after the initial infection. Previous research has also reported EBV reactivation in people with COVID-19, adding to growing evidence that SARS-CoV-2 infection can disturb the balance between the immune system and viruses already present in the body.
Researchers say the findings could eventually help scientists identify biomarkers that predict which patients are more likely to develop prolonged symptoms or complications. It may also open new avenues for investigating treatments that target viral reactivation alongside the effects of SARS-CoV-2.
The study highlights the complex relationship between COVID-19, the immune system and viruses that can remain hidden in the body for years. While more research is needed to determine exactly how these reactivated viruses affect recovery, the findings provide another potential explanation for the wide range of health effects associated with severe COVID-19 and Long COVID.
