SARS-CoV-2 virulence evolution: Avirulence theory, immunity and trade-offs

Abstract

The COVID-19 pandemic has led to a resurgence of the debate on whether host–parasite interactions should evolve towards avirulence. In this review, we first show that SARS-CoV-2 virulence is evolving, before explaining why some expect the mortality caused by the epidemic to converge towards that of human seasonal alphacoronaviruses. Leaning on existing theory, we then include viral evolution into the picture and discuss hypotheses explaining why the virulence has increased since the beginning of the pandemic. Finally, we mention some potential scenarios for the future.