Blood group may play small role in COVID-19 infection risk, Royal Society report says

A person’s blood group appears to modify their risk of infection and chances of developing COVID-19, according to a new report by the Royal Society’s SET-C (Science in Emergencies Tasking: COVID-19) group.

The ABO Blood Groups and COVID-19 report (PDF) concludes that blood group O individuals’ risk of being infected by the SARS-CoV-2 virus are around 25% lower than someone with a non-group O blood type. Blood group A individuals appear to have a higher risk of infection.

Blood group is genetically determined and its effect on COVID-19 risk is small, particularly when compared to other risk factors where protective measures can be taken.

A meta-analysis considered by the review also found the risks of needing intubation, or of dying from COVID-19, did not vary significantly by blood type.

Professor Charles Bangham, Chair of Immunology at Imperial College London and lead author of the SET-C report, said: “This sheds some light on another aspect of how the disease is caused, but it has more implications for understanding the mechanisms of infection and how we might treat it – than for prevention.”

“There is a small reduction in the risk of COVID-19 in people with blood group O, however, the protective effects of already recommended measures, especially social distancing, face coverings and hand-washing, are much more important for lowering our risk.”

The report considers possible mechanisms that could explain this effect and which should be studied further.

Almost half the UK population is blood group O, according to the NHS website, and the frequency of different blood groups varies internationally and by ethnic group.

There are other diseases where group O blood has been shown to be protective, most notably malaria, where it lowers the risk of severe forms of the disease.

The report provides a rapid review of published scientific evidence on the topic to support policy makers and has not been through formal peer review.

The Royal Society is grateful to the Leverhulme Trust for its support for the Society’s pandemic response work.

All reports published by the SET-C group can be found on the Royal Society webpage SET-C (Science in Emergencies Tasking – COVID).