To date, lactoferrin’s effectiveness in improving COVID-19 clinical outcomes has been evaluated in several cohort studies in the adult general population with conflicting results: in early studies involving asymptomatic or mildly symptomatic patients, lactoferrin administration reduced the time to negativization and/or prevented the infection, while in recent studies, involving moderate and severe hospitalized patients, it failed to improve disease course. This evidence concerns the gene LTF and infection.