CDC's FAQ on the delta variant mentions it "might cause more severe illness than previous variants in unvaccinated people."

Also quoted from CDC's FAQ:

> "In two different studies from Canada and Scotland, patients infected with the Delta variant were more likely to be hospitalized than patients infected with Alpha or the original virus that causes COVID-19."

https://www.cdc.gov/coronavirus/2019-ncov/variants/delta-var...

This summary from august points to a couple studies that support the general 2x hospitalization rate in unvaccinated delta patients.

Honestly I wasn’t aware that there was this much uncertainty at the time, I remember hearing that delta was affecting young people in India more strongly way back in early 2021

https://www.ucsf.edu/news/2021/08/421171/how-dangerous-delta...

It doesn't work like that. Delta and original existed at different times. Testing was way more advanced this year than last. So you would expect a larger denominator.

Ok. That wiki page cites this report from the UK on those stats (which seem to be derived from raw values in the tables maybe?) [0].

The thing is, it’s not straightforward to answer the question “was delta more severe/virulent than alpha or wild type” from directly comparing these raw statistics. The Delta wave in the UK (and US) was post vaccine rollout, so you can’t say from the raw numbers whether it’s the virus that changed, the demographics of people with infections, or vaccine rollout.

Analyses considering these confounding factors point to delta being more virulent, and towards the (thankfully!) lower fatality rate being mediated by vaccine efficacy and demographics.

This is the same situation we seem to possibly be in with omicron, but we still lack good data on how hard it hits the immunologically naive relative to previous variants

0: https://assets.publishing.service.gov.uk/government/uploads/...