T-cell immunity status of children with combined infection with SARS-CoV-2 and human herpesviruses

There is an opinion that COVID-19 may be the cause of the reactivation of herpesviruses. Purpose. To study the state of the cellular link of adaptive immunity in the combined course of herpesvirus infections and COVID-19, to describe the clinical and laboratory characteristics of such conditions. Material and methods. In 2022–2023 a cross-sectional study was conducted. 71 patients aged from 1 month to 16 years were selected. Inclusion criteria: presence of signs of acute respiratory disease associated with SARS-CoV-2 and/or mononucleosis-like syndrome associated with active herpesvirus infection. All patients underwent a standard laboratory examination, determined by nosology, and an additional assessment of the cellular link of adaptive immunity (CD3+, CD4+, CD8+, CD3+HLA-DR+, CD3- CD16+CD56+ and CD20+) on a flow cytometer using monoclonal antibodies. Results and conclusion. The clinical pattern of the combined course of herpesvirus infection and SARS-CoV-2 differs little from monoinfections. Only at the first encounter with the Epstein-Barr virus, lymphoproliferative syndrome and hepatomegaly were more often recorded (p<0.05). Comparing the nature of the cellular immune response in patients with COVID-19 and herpesvirus infection, we observed pronounced differences. In patients with primary herpesvirus infection, the T-cell immune response was an order of magnitude higher than in acute COVID-19, herpesvirus reactivation, and co-infection, and this was true for all studied lymphocyte subpopulations. With SARS-CoV-2, a decrease in the total number of T-lymphocytes, T-helpers, and cytotoxic lymphocytes was observed. This condition, of course, cannot be called immunosuppression, but some parallel is clearly traced. And even with the combined course of SARS-CoV-2 and herpesvirus infection, the absolute values of T-cell immunity indicators do not reach the same indicators in patients without COVID-19. It is likely that this reason underlies the phenomenon of reactivation of persistent herpesviruses in patients infected with SARS-CoV-2.