Blood Type O has been implicated as a risk factor by one study reported early on from patients studied in Wuhan itself.
https://www.newsweek.com/blood-type-coronavirus-covid-19-1492890
I don’t think this study has been replicated or the conclusion confirmed elsewhere in the world, so whether it is generally correct and/or applies to non-Chinese populations, is anybodies guess....
oops. Sorry-my typo there— it is said that “blood group A had a significantly higher risk for COVID-19”, NOT group O.....