Polymorphisms in MBL and FcγRII have been associated with susceptibility to or severity of some infectious diseases, such SARS-CoV or influenza (Fricke-Galindo and Falfán-Valencia, 2021; Mehrbod et al, 2021; Yuan et al, 2005) as well as COVID-19 (López-Martínez et al, 2022; Malaquias et al, 2021; Medetalibeyoglu et al, 2021; Stravalaci et al, 2022), but whether these affect the complement activation and negative feedback mechanism remains to be investigated. The gene discussed is MBL2; the disease is COVID-19.