Is it true that type O blood is not easy to be infected with COVID-19's disease?

According to the latest research results released by China south university of science and technology of china, Shanghai Jiaotong University, Wuhan Zhongnan Hospital and Wuhan Jinyintan Hospital, COVID-19 susceptibility is related to blood type. The latest research in COVID-19 shows that patients with type A blood are more susceptible to infection, and the relative risk of type O blood is lower. Specifically, type O blood is not particularly favored by COVID-19, and it is relatively difficult to infect COVID-19; On the other hand, type A blood is not so lucky, and the risk of COVID-19 virus infection is relatively high.

In the paper "Relationship between ABO Blood Group and Susceptibility to Coronavirus Pneumonia-19", the research group collected ABO blood samples from patients in Jinyintan Hospital 1775, People's Hospital of Wuhan University13 and 285 patients with COVID-19 infection in Shenzhen Third People's Hospital.

Then the blood group distribution data of 3694 people in Wuhan and 23386 normal people in Shenzhen were compared respectively.

(The proportion of type O blood in normal people in Wuhan is 33.84%, while that in patients in Jinyintan Hospital is only 25.80%).

Finally, the conclusion of the paper is that the risk of COVID-19 virus infection in people with type A blood is higher than that in people with non-type A blood, and the risk of COVID-19 virus infection in people with type O blood is lower than other people.

Due to the small sample size, the research team also pointed out that the correlation of this set of data did not reach statistical significance. Even so, this study still has certain clinical guiding significance. So what is the relationship between blood type and infectious diseases? How does blood type determine the risk of human disease? Do people with type O blood have a natural advantage in the face of infectious diseases?

Let's talk about how blood types are classified first.

The blood type of human body is determined by the specific antigen in the body. Antigen is a kind of sugar attached to the surface of red blood cells, which is closely related to clinic, mainly including type A and type B. If you only have type A antigen in your body, then you are type A blood; If you only have type B antigen, then you are type B blood; If you have both, you are AB blood; If you have neither, you are type O.

Why do different blood types have different risks of infectious diseases?

The key point is that the antigen that determines blood type interacts with pathogens, viruses and even human immune system in vivo, so that human immunity to some infectious diseases can be enhanced or weakened. Because this study discussed the relationship between ABO blood group and susceptibility to coronavirus pneumonia-19 by statistical method, it did not explain why O blood group was relatively less susceptible to infection. Next, we will take malaria (compared with other blood types, blood type O is less susceptible to infection) as an example to reveal how antigens interact with pathogens, thus leading to differences in susceptibility.

In the face of malaria, people with type O blood have a natural advantage.

Malaria causes death because red blood cells parasitized by plasmodium will express an adhesion molecule on the cell membrane, which will combine with blood group antigens on uninfected red blood cells to form a blood clot like a rose. This rosette is attached to vascular endothelial cells, which leads to vascular occlusion and serious diseases. The number of rosettes is directly proportional to the severity of infection.

Studies have shown that this adhesion molecule has strong affinity for blood group A antigen and weak affinity for B antigen. Therefore, after being infected with malaria, people with type A blood can form more rosettes than people with type B blood and type O blood.

At present, the above research results can also be inferred from the global population distribution of type O and type A blood. In tropical areas, such as Central America and South America, malaria is very prevalent, and now most indigenous people have O blood. Malaria is less prevalent in cold regions, such as Scandinavia, Greenland and the Arctic Circle in Europe and North America. Blood type A is the blood type with the highest occurrence rate. These data prove from another angle that type O blood is beneficial to anti-malaria, while type A blood is not. In addition, some studies have pointed out that there are more people with type A blood in Europe, which may also be the reason for the spread of smallpox.

Of course, type O blood is not always dominant.

People with type O blood are more likely to escape malaria, but in the face of cholera, the probability of being infected is greater than that of people with other blood types. A large number of studies have shown that people with type O blood are more prone to serious infection than those without type O blood. The Ganges Delta in Bangladesh is a high incidence area of cholera, and almost all cholera epidemics in modern times spread from this area. It is considered that the small number of O-type blood and the large number of B-type blood in this area in modern times are directly related to the early cholera selection pressure.

Similarly, a gastrointestinal infection caused by Escherichia coli O 157 broke out in Scotland in 1996, and 87.5% of the dead were O-type blood, which means that people with O-type blood may be more sensitive to this bacteria.

The reason is that A and B antigens can help the human body to prevent these bacteria from combining with some cells in the body, and this protection mechanism does not occur in the blood, but in the intestine, which is the workplace of cholera bacteria and Escherichia coli. Although cholera toxin can still bind to human cells with A and B antigens in the body, it will bind more strongly to O blood, so people with O blood have a higher risk of cholera.

Blood types also show different sensitivities to SARS virus.

Previously, for other types of coronavirus, there were also blood group-related studies, and the conclusion was similar to that of COVID-19. For example, previous studies by Chen Yufeng and others of the Chinese University of Hong Kong show that Hong Kong's susceptibility to SARS-CoV virus can be distinguished by ABO blood group system. The study found that compared with non-O-blood medical staff, O-blood medical staff are less susceptible to infection. However, in COVID-19, the mechanism between blood type and SARS-CoV virus susceptibility also needs further research to clarify.

Many studies have confirmed that there is indeed a relationship between blood type and infectious diseases, but there is no difference between blood types. Understanding the relationship between blood type and infectious diseases is also for better prevention and control. Let's look forward to more research on COVID-19!