Breathing more breadth into COVID-19 T cell responses.

Innate and adaptive heterologous immunity confers resistance to pathogens. However, its impact on resistance and the course of human infection have remained largely elusive, hampering the use of this phenomenon to enhance vaccine efficacy. In this issue of Med, Mysore et al. show that T cell responses elicited by SARS-CoV-2 infection or vaccination correlate with those induced by MMR and Tdap immunization, revealing the transcriptomic basis of these correlations and find that heterologous adaptive immunity contributes to a better prognosis of COVID-19 disease.1.