This tweet has this nice graph, made with data pulled from the Public Health England Variants of Concern Technical Briefing 22.
This preprint from Denmark says that people who were not fully vaccinated were 2.8x times as likely to get hospitalized for Delta as for Alpha. (For people who were fully vaccinated, there wasn’t much difference.) They caution, however, that this might be due to different testing patterns, age distributions, or social behaviour.
In the study described in this preprint, they pitted antibodies from the blood of people vaxxed with Pfizer and people who had gotten had been sick with COVID-19 against different VOCs: Alpha, Beta, and Gamma. They found that the antibodies didn’t work nearly as well against those VOCs than they did against COVID Classic, especially against Beta. People who had had COVID-19 disease but had not been hospitalized had particularly crummy antibodies.
This might be moot, given how Delta waaay out-competes Alpha, Beta, and Gamma.
There has been concern that Delta is unusually dangerous for kids. This report from the US CDC says that the proportion of sick kids isn’t much different with Delta as in the past.
(Yes, there have been a lot of articles about pediatric wards in the US filling up, but that’s partly because ALL the wards in the US are filling up and because there’s a lot of kids sick with RSV right now.)
This preprint found four markers in the blood which correlate highly (75%) with Long COVID. This is good, it not only could lead to a test for Long COVID (useful for convincing doctors that it is not all in the head) but also give clues to why it is happening and therefore how to treat it.
This is another great article about the “are vaxxes losing effectiveness” debate, talking about all the reasons why it is hard to tell.