Why do some people infected with the coronavirus suffer only mild symptoms, while others become deathly ill? A new study by European scientists is the first to document a strong statistical link between genetic variations and Covid-19.

Variations at two spots in the human genome are associated with an increased risk of respiratory failure in patients with Covid-19 – one of these spots includes the gene that determines blood types. Having Type A blood was linked to a 50% increase in the likelihood that a patient would need to get oxygen or to go on a ventilator, according to the new study.

Learn more about what researchers found in the study here, which has not yet been through peer-review.