A pair of recent studies found that people with Type A blood are no more at risk of getting the virus or falling dangerously ill than others, contradicting preliminary evidence based on a relatively small sample of people.

Over the past few months, after looking at thousands of additional patients with Covid-19, scientists are reporting a much weaker link to blood type.

Two studies — one at the Massachusetts General Hospital and the other at Columbia Presbyterian Hospital in New York — did not find that Type A blood increases the odds that people will be infected.

The new reports do find evidence that people with Type O blood may be slightly less likely to be infected. But the effect is so small that people shouldn’t count on it. “No one should think they’re protected,” said Nicholas Tatonetti, a data scientist at Columbia University.

Even if blood types don’t matter much for treating people with Covid-19, they could reveal something important about the basic nature of the disease.

That’s because blood type influences how your immune system fights against infections. People with Type A blood do not make the same kind of antibodies as people with Type B blood, for example. It is conceivable that these molecular differences in the immune system explain the purported link between blood type and coronavirus infections.

BLOOD TYPESNew studies show there is not a connection between a person’s blood type and vulnerability to the virus.