IFNG and COVID-19: Groups of participants vaccinated with one of the SARS-CoV-2 vaccines and participants without a history of SARS-CoV-2 infection or vaccination had a higher percentage of participants who were infected with SARS-CoV-2, while groups of participants with previous COVID-19 (before IFN-γ testing) and participants who had both the SARS-CoV-2 infection and vaccination history have a higher percentage of participants who did not have a SARS-CoV-2 reinfection.