The circulation of SARS-CoV-2 Delta (i.e., B.1.617.2) variants challenges the pandemic control. Our analysis showed that in the United Kingdom, case fatality ratio (CFR) decreased from May to July 2021 for non-Delta variant, whereas the decreasing trend of the CFR of Delta variant was weak and insignificant. The association between vaccine coverage and CFR appears stratified by different circulating variants. Due to the limitation of ecological study design, the interpretation of our results should be treated with caution.
Differences in the case fatality risks associated with SARS-CoV-2 Delta and non-Delta variants in relation to vaccine coverage: An early ecological study in the United Kingdom