A genetic study indicates that your blood type may influence how unwell you get from COVID-19

COVID-19 has a number of identified risk factors, the most prominent of which are age and immunocompromised status. Now, it appears that one's blood type may influence the severity of COVID-19 symptoms, adding an unanticipated wrinkle to our understanding of SARS-CoV-2, the virus that causes COVID-19.

Those with Type A blood are more likely to become extremely ill from COVID-19, according to a study published this week in the journal PLOS Genetics. Scientists tested over 3,000 blood proteins in the study to see which ones were responsible for positive or negative COVID-19 outcomes. In this case, "severity" was defined as a COVID-19 case that required hospitalization and/or respiratory help — or even resulted in the patient's death. The scientists had down the list of likely protein suspects to just over a dozen by the time they were finished, and one of them happens to be a protein that defines your blood type. 

"Our study does not link precise blood group with risk of severe COVID-19," said Christopher Hübel of King's College London, "but since previous research has found that the proportion of people who are group A is higher in COVID-19 positive individuals, this suggests that blood group A is a more likely candidate for follow-up studies."

This isn't to say that persons with Type A blood should be concerned. Obesity, age, and pre-existing immunological illnesses are all factors that are significantly more likely to put a person prone to serious illness than blood type. Even so, clinicians should be aware that a patient's blood type has an impact on their prognosis. Furthermore, there are implications to the findings that go beyond the immediate blood type issue.

"What we've done with our study is present a shortlist for the next step of research," said Gerome Breen of King's College London, the report's co-last author. "We whittled it down to about 14 blood proteins that have some form of causal connection to the risk of severe COVID-19 and present a potentially important avenue for further research to better understand the mechanisms behind COVID-19 with the ultimate goal of developing new treatments but also potentially preventative therapies," says the researcher.