The DNA testing company 23 and Me has been using their massive data sets to assist scientists with analysis in how COVID-19 spreads and if genetic factors play a role in determining how likely someone is to get infected and how severe the infection will be.

While not definitive, some of their early data seems to confirm that blood type may be a factor in transmission and immunity.

“In percentages, in the entire population, individuals with blood group O were 9-18% less likely to test positive when compared to other groups. “Exposed” individuals with blood group O were 13-26% less likely to test positive.”

Read more: Large Study Suggests Blood Type O May Be a Protective Factor Against COVID-19