Asymptomatic SARS-CoV-2 people with blood group AB at the highest risk

The COVID-19 pandemic has led to several waves of infections in many countries around the world. The significant differences in mortality rates between different geographic regions suggest that human susceptibility to the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) varies significantly.

Scientists around the world are doing extensive research to understand the nature of the virus, its kinetics of transmission, etc. They found a strong correlation between the ABO blood group and SARS-CoV-2 in terms of its morbidity and mortality.

Previous research

Previous studies have shown the relationship between the ABO blood type and several viral diseases. Researchers have reported that among the people who live in the Indian Gangetic Plain, those with blood type O are the most susceptible to cholera and Helicobacter pylori infections. Even so, it has been reported that this blood type is less susceptible to dengue and Severe Acute Respiratory Syndrome (SARS) viruses.

blood type

The ABO blood group is determined by the ABO gene present on chromosome 9. Several research has shown that this gene, directly or indirectly, mitigates an individual’s sensitivity to COVID-19. Further research has indicated that some of the variants of this gene could play an important role affecting the morbidity and mortality of many diseases, including COVID-19. For example, the ABO gene affects the physiology of red blood cells, type 2 diabetes, venous thromboembolism, heart-related functions, ischemic stroke, and coronary artery disease. Scientists believe that understanding how ABO blood type affects SARS-CoV-2 infection is important as it can help determine the factors that make a person susceptible to SARS-CoV-2.

The study

New research results are now being published on the medRxiv * preprint server that focus on the association between a person with blood group ABO and asymptomatic COVID-19 positive. This is the first report to look at the association between blood type and the incidence of asymptomatic COVID-19 infection.

This study used random serosurveillance and blood type tests from street vendors in northern India. The data were collected from 509 people from three districts of the eastern Uttar Pradesh region. Researchers have reported that the seroprevalence of all districts included in this study was greater than 0.4. This increased seroprevalence indicates that the majority of SARS-CoV-2 infections are due to asymptomatic infections. Although seroprevalence is not consistent in all Indian districts, many independent regions reported high seroprevalence. It is found that the seroprevalence is sporadic rather than uniform.

Current research found a frequency distribution for blood groups A, B, O and AB of 0.204, 0.354, 0.279 and 0.163, respectively, among 509 samples. Scientists reported that blood type B is the most common type in the eastern region of Uttar Pradesh, followed by blood type O and the least common type was AB. To verify that these data represent the true blood type distribution of the region, the scientists obtained published data from the same region and performed regression analysis. The adjusted R-squared value (96.7% + 2.7%) showed a high degree of correlation between the data (current study) and the previously published data. This result showed that the data considered for the current study actually represented the regional distribution of blood groups.

The blood type of SARS-CoV-2 infected people was estimated and grouped. Scientists have reported that the ABO blood group distribution of 215 seropositive individuals had a frequency of 0.223, 0.312, 0.107 and 0.358 of the A, B, O and AB blood types. In this study, a significant inconsistency in the relative blood group distribution was found, particularly between O and AB. In the seropositive group, blood group AB was significantly higher, while blood group O was significantly lower. This result is similar to the previously published data on seropositive individuals. Current research has found a strong association of blood groups O and AB with susceptibility to COVID-19.

When assessing which blood type is at higher risk of COVID-19 infection, scientists found that people with blood type AB are at a much higher risk of COVID-19 infection than people with blood type O. This study developed a risk scale indicating that people with blood type AB are most susceptible or at highest risk of being infected with SARS-CoV-2, followed by blood type A and B. However, blood type O is at the bottom end on this risk scale, which indicates that this blood group has a significantly lower risk of infection. Previous research showed that the rh-negative blood group plays a protective role against SARS-CoV-2. This study found no association between the Rh factor and COVID-19. It must be mentioned, however, that there were a limited number of Rh negative samples.

One of the limitations of this study is that it did not include data on people severely infected with SARS-CoV-2. The relationship between blood group and COVID-19 severity is not projected. However, an interesting finding from the research is that while the AB blood type is most susceptible to COVID-19 infection, it may not have a high risk of severity. Larger data would help draw more determined conclusions.

* Important NOTE

medRxiv publishes preliminary scientific reports that are not peer-reviewed and therefore should not be considered conclusive, guide clinical practice / health-related behavior, or treated as established information.

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