By Mark Waghorn
COVID-19 is like a vampire with a taste for people with blood type A, according to new research.
A spike protein that enables it to invade hosts latches onto carriers with a relish similar to Dracula.
The fanged Count has been said to be a metaphor for viruses, reflecting late-19th Century fear of contagion.
Now a study has shed fresh light on why the Coronavirus is deadly for some while others are not even aware they have had it.
Experiments showed SARS-CoV-2, the virus that causes COVID-19, is better at infecting individuals with blood group A than those with B, AB or O.
The discovery provides a direct link with COVID-19 and higher rates of infection. Identifying risk factors opens the door to developing potential therapies.
Lead author Dr. Sean Stowell, of Harvard Medical School, said: “We show the part of the SARS-CoV-2 spike protein that’s key to enabling the virus to invade cells displays affinity for blood group A cells.
“The virus in turn also shows a preferential ability to infect blood group A cells.”
Most of us don’t know what our blood type is. It only becomes an issue if we need a transfusion.
The study in the journal Blood adds to evidence A carriers – who number about a third of the population – are most susceptible to COVID-19.
Nearly four-in-10 have group O. Previous research has suggested they are least vulnerable. Their risk of organ failure – and even death – is also reduced.
The US team has now identified a smoking gun- a mechanism that might explain the phenomenon.
In the lab, Stowell and colleagues added a protein that stopped SARS-CoV-2 from recognizing blood antigens, substances that cause an immune response.
It blocked the virus’ preference for infecting blood group A cells, but had no effect on blood group O.
The addition of a different protein that didn’t block the recognition of blood group antigens had no infection-inhibiting effects on either A or O cells.
Stowell said: “Blood group A cells were more likely to be infected with SARS-CoV-2 when compared with blood group O cells.”
Further tests showed the Omicron strain of COVID-19 had an even stronger preference for blood group A cells than the original virus.
But the findings do not mean people with blood group O have no need to take precautions against infection.
Stowell said: “Among a group of several thousand people, some studies suggest that those with blood group A may be 20 per cent more likely to be infected after exposure to SARS-CoV-2 compared with those who have blood group O.
“But people with blood group O can still contract the virus and may transmit it to others.
“Moreover, factors such as age and chronic conditions like heart disease rank higher than blood type in determining individuals’ risk for severe SARS-CoV-2 infection.”
He added: “Blood group is one of many variables that influence one’s likelihood of becoming infected following exposure to SARS-CoV-2.
“Regardless of their blood group, individuals should be fully vaccinated against Covid-19 and should continue to take other preventive measures appropriate to their risk level.”
It has been claimed Bram Stoker’s 1897 novel was influenced by Victorian notions of infectious disease.
Vampirism could spread through a population like smallpox, cholera, and a host of other illnesses.
Future studies will be needed to uncover features ultimately responsible for engaging blood group A with implications for the emergence of new variants.
Produced in association with SWNS Talker
Edited by Jessi Rexroad Shull and Kyana Jeanin Rubinfeld