A new research study published in The New England Journal of Medicine has found an intriguing pattern among those with severe cases of COVID-19.

The relatively limited study, in which approximately 2,000 European patients with severe cases of the disease were compared to people infected with the SARS-CoV-2 coronavirus who presented mild or no symptoms, appears to demonstrate that one's blood type can impact the way one experiences the disease.

Patients with type A blood were more prone to having severe COVID-19; those with type O were less so. Blood types are grouped according to the antigens on the surface of red blood cells; one hypothesis among researchers is that the proteins on type O blood are relatively more effective at "identifying" protein patterns on certain viruses.

Coronavirus.

Image source: Getty Images.

This study is not the first of its kind. A similar one conducted in China and published in March came to broadly the same conclusions. Although neither proves a link between blood groups and COVID-19 severity, the findings provide a promising avenue for future research. So far, there are no proven cures and no approved vaccines for COVID-19.

Many of the world's top pharmaceutical companies and biotechs are working to change that. Just now, the most promising drugs on the treatment front are the antiviral remdesivir from Gilead Science (NASDAQ: GILD), and the steroid dexamethasone, which has been in use medically since the 1950s and is widely available as a generic drug. On the vaccine side, Novavax's (NASDAQ: NVAX) NVX-CoV2372 currently seems to have momentum. Its speedy development also being bolstered by millions of dollars in public and private funding raised by the company.

Neither Gilead nor Novavax has yet commented on this latest published research into the connection between blood type and COVID-19 severity.

In pre-market hours on Friday, Novavax shares were up sharply (by 7.3%) while Gilead's had risen a more modest 0.2%; the former was outpacing futures trading on the top equity indexes, the latter attempting to catch up.

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