Delta had equal or higher severity per infection than alpha which in turn had higher severity than the original variant. It just had lower mortality than the fi

Delta had equal or higher severity per infection than alpha which in turn had higher severity than the original variant. It just had lower mortality than the first wave because people had higher preexisting immunity, treatment had improved, and some of the most vulnerable had already been culled from the herd. You have to compare between two variants at the same time, not against previous waves. Omicron is the first major variant to actually be less severe on this metric.