TIGIT and nosocomial infection: Herein, we performed immunophenotyping of TIGIT+ and TIGIT- Treg subsets in blood samples collected from unvaccinated patients with COVID-19 at their hospital admission from May 29th to August 6th, 2020, in an attempt to identify whether increased levels of TIGIT+Tregs could imply mechanical ventilation requirement and increased susceptibility to nosocomial infection during hospitalization.