A person’s blood group has an influence on their chances of becoming severely ill when infected by the coronavirus, according to an international study carried out on nearly 4,000 people in two countries.
The study shows that patients with blood type A have 45% more than average chance of developing severe symptoms of the disease Covid-19 caused by the virus. The majority of fatal cases involve serious respiratory failure requiring respirator support in intensive care.
The study looked at 835 patients and 1,255 control subjects in Italy, and 775 patients and 950 control subject in Spain – two of Europe’s earliest and most affected countries.
They then looked to see if there was evidence that genetic factors could be linked to the likelihood of developing serious symptoms of Covid-19.
And indeed, they discovered a link between blood type A and the development of severe symptoms.
Despite what the Belgian Red Cross has described as a “particularly high-quality” study, the organisation said there was no reason to panic.
“It is not because you have blood type A that you will end up in hospital with serious breathing problems once you become infected with the coronavirus,” said Nena Testelmans, a science journalist who works for the Red Cross in Flanders.
“It is not yet even sure that your blood type has an impact on the course of the disease when you are infected. and there are also many other factors that determine that course.”
Among those unrelated risk factors are high-risk conditions such as obesity, diabetes and high blood pressure, and most of all age. More than half of all confirmed cases were over the age of 60, with 40% over the age of 70.
More than half of all deaths were people aged over 75, according to figures from federal health institute Sciensano.
The Red Cross stressed – following the basic scientific principle that correlation is not causation – that the connection, however respectable the study, requires more work to determine the exact link, and the mechanism by which blood type affects health outcomes.