Three hospitals in China provinces, Wuhan and Shenzhen , compared the data of patients (2173)  infected with the novel Coronavirus strain 2019 and tried to find a correlation between the blood group type and vulnerability to nCoV-2019 disease. The performed ANOVA tests and statistical analyses with mathematics models based on random effects, the investigators concluded that the risk for infection with nCoV-2019 (a.k.a SARS-CoV-2) is significantly higher for people with blood group A in comparison with those with non-A blood groups. The risk for O-group people is lowest according to the analysis.
The exact mechanism behind this correlation is yet to be determined and it might give entirely new perspective on both the nature of the infection and the possible treatments and prevention of nCoV-2019.

blood group types relation to coronavirus infection
Schematic overview of the A, B, AB and O blood group types
nCoV-2019