Increased Transmissibility and Lowered Lethality of the Delta Variant: Is Covid-19 Becoming More Like Flu?

In this study, we used data from the UK and the US to compare the case fatality of the Delta variant of concern (VOC) with previous ones and found a 10-fold difference between Delta VOC and previous SARS-Cov-2 trains, which cannot be explained by vaccination. The weakened pathogenicity in predominant strains in an epidemic is highly anticipated over time according to the evolution theory.