In a study published in the journal Frontiers in Immunology, researchers from Linkoping University, Sweden, in collaboration with the Bragee Clinic in Stockholm, revealed that COVID-19 can reactivate several latent viruses lurking in the body′s cells following previous infections, particularly in people with chronic fatigue syndrome.

In the study, 95 patients diagnosed with myalgic encephalomyelitis/chronic fatigue syndrome, also known as ME/CFS, were enrolled along with 110 healthy controls. The participants provided blood and saliva samples on four occasions during the year.

The researchers analyzed the samples and found a special antibody fingerprint against common herpes viruses in saliva. Out of the nine known human herpes virus types, Epstein-Barr virus (EBV) was found in nearly every participant. The EBV virus′ proliferation leads to immune system impairment, causing fatigue, autoimmune responses, and an increased risk of lymphoma.

The researchers stated that around half of the participants were infected with SARS-CoV-2 during the first wave of the pandemic and developed mild COVID-19. After the SARS-CoV-2 infection had passed, however, the researchers detected specific antibodies in the saliva that suggested that three latent viruses had been strongly reactivated, one of them being EBV. Both the ME/CFS and control groups experienced reactivation. However, the response to the reactivation was significantly stronger in the ME/CFS group.

The study author noted that the symptoms of ME/CFS and long-term COVID overlap to a great extent, which is experienced by around one-third of patients who contract COVID-19. He noted that exhaustion after light exercise, brain fog, and unrefreshing sleep are common symptoms, while impaired lung capacity and abnormal senses of smell and taste are more specific to long-term COVID. 

(Source: https://health.economictimes.indiatimes.com/news/diagnostics/covid-19-infection-may-reactivate-several-latent-viruses-in-body-study/95584995 )