Researchers detected renewed activity from several common viruses in nearly half of the hospitalised COVID-19 patients they studied. The findings, published in the journal Nature on Wednesday, showed that reactivation was associated with more severe COVID-19, increased inflammation and poorer clinical outcomes. The researchers stressed, however, that the study did not prove that the reactivated viruses caused severe illness or long COVID. Viruses reactivated at different timesThe researchers found that the viruses did not reactivate simultaneously. The researchers found associations between severe COVID-19 and the reactivation of Epstein-Barr virus, cytomegalovirus, herpes simplex virus and anelloviruses.