SYN1 and COVID-19: In the present study we assessed the transcriptional levels of (1) type I, II, and III IFNs and/or of their ISGs, (2) TRIM28 and SETDB1, and (3) HERV sequences of env genes of SYN1, SYN2, MSRV, and of pol genes of HERV-H, -K, -W, the three retroviral families most widely studied, in children with mild/moderate or severe clinical manifestations of COVID-19 and in uninfected control children.