23andMe finds evidence that blood type plays a role in COVID-19 

Preliminary data from 23andMe’s ongoing genetic study of COVID-19 appears to lend more evidence for the importance of a person’s blood type — determined by the ABO gene — in differences in the susceptibility to the virus.

23andMe is still recruiting for its massive study, most recently seeking 10,000 participants outside of 23andMe who have been hospitalized and diagnosed with COVID-19. 23andMe researchers have yet to finish looking at what the genetic data indicate.

But a first blush look at the information from the more than 750,000 participants in the study shows the following: 

  • The preliminary data suggest that O blood type appears to be protective against the virus when compared to all other blood types. 
  • Individuals with O blood type are between 9-18% percent less likely than individuals with other blood types to have tested positive for COVID-19, according to the data. 
  • There appeared to be little differences in susceptibility among the other blood types. 
  • These findings hold when adjusted for age, sex, body mass index, ethnicity, and co-morbidities.
  • Although one study found the blood group O only to be protective across rhesus positive blood types, differences in rhesus factor (blood type + or -) were not significant in 23andMe data. Nor was this a factor in susceptibility or severity in cases.
  • Among those exposed to the virus — healthcare and other front line workers — 23andMe found that blood type O is similarly protective, but the proportion of cases within strata is higher.
Preliminary Genetic Association

While it is still very early in the study, 23andMe’s preliminary investigation into genetics seems to support these findings. Comparing the research participants who reported that they tested positive for COVID-19 to those who tested negative, our researchers identified a variant in the ABO gene associated with a lower risk. (The single nucleotide polymorphism in the ABO gene is rs505922, a T at that location is associated with lower risk. The P-value for the association is 1.4e-8, OR = 0.88).

Both the data on blood type and the preliminary genetic findings also appear to support at least two recently published pre-print studies — one by researchers in China and the most recent one by researchers in Italy and Spain — that look at the ABO gene’s role in COVID-19. The study in China looked at susceptibility, while the Italian and Spanish study found an association with blood type and severity of the illness.  

Numerous other studies have reported that the ABO blood group plays a role in both susceptibility and severity for COVID-19 (refs: 1, 2, 3). And we know from other studies that the ABO blood group can play a direct role in other types of infections by serving as receptors, or coreceptors for microorganisms, parasites, and viruses. The preliminary findings from 23andMe’s data are also notable because of the link between COVID-19 blood clotting, and cardiovascular disease

Comparing Blood Types

23andMe researchers wanted to investigate this link with blood type, so we estimated the contribution to risk by comparing each blood group against each of the others. Because the differences are quite small, an extremely large sample size is needed to explore differences across groups. For 23andMe’s study, which now includes more than 750,000 individuals, we investigated the cumulative incidence of self-reported COVID-19 by blood type, hospitalization by blood type, and proportion of those infected after known exposure by blood type. 

Here is what we found.

23andMe Blog

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