Previous studies reported that the hepatitis C virus (HCV) could help disseminate the hepatitis D virus (HDV) in vivo through the unrelated hepatitis B virus (HBV), but with essentially inconclusive results. To try to shed light on this still-debated topic, 146 anti-HCV-positive subjects (of whom 91 HCV/HIV co-infected, and 43 with prior HCV eradication) were screened for anti-HDV antibodies (anti-HD), after careful selection for negativity to any serologic or virologic marker of current or past HBV infection. One single HCV/HIV co-infected patient (0.7%) tested highly positive for anti-HD, but with no positive HDV-RNA. Her husband, in turn, was a HCV/HIV co-infected subject with a previous contact with HBV. While conducting a thorough review of the relevant literature, the authors attempted to exhaustively describe the medical history of both the anti-HD-positive patient and her partner, believing it to be the key to dissecting the possible complex mechanisms of HDV transmission from one subject to another, and speculating that in the present case, it may have been HCV itself that behaved as an HDV helper virus. In conclusion, this preliminary research, while needing further validation in large prospective studies, provided some further evidence of a role of HCV in HDV dissemination in humans.

Some studies suggested a high incidence of human herpesvirus (HHV) reactivation in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. To evaluate the prevalence of HHV reactivations in a population with various severity degrees of coronavirus disease 2019 (COVID-19), we analyzed 102 individuals and compared them with 51 SARS-CoV-2-negative subjects admitted in the same period (January–July 2022) for acute respiratory failure. Positivity was found in 76% of subjects for at least one HHV, and in 46% for ≥2 HHV. These proportions were more prevalent in SARS-CoV-2-positive than in negative patients (83% vs. 61%; 56% vs. 27%, respectively). The most common HHV was HHV-7 both in the whole population (51%) and in SARS-CoV-2-positive and -negative subjects (57% and 39%, respectively); human cytomegalovirus, herpes simplex virus-1, Epstein–Barr virus, and HHV-6 were more represented in SARS-CoV-2-positive individuals. No single or combined HHV reactivation was associated with the 60-day mortality rate. However, cytomegalovirus reactivation was an independent predictor of COVID-19 severity and longer hospitalizations, while the occurrence of ≥3 any HHV reactivations was independently associated with the aforementioned outcomes and ventilatory support need. Taken together, our data suggest that in patients with moderate-to-severe COVID-19, the diagnosis of HHV coinfections can add useful prognostic information.