The contemporary 21^st century has witnessed three important afflictions through coronaviruses. The primary epidemic occurred in 2002 in China by severe acute respiratory syndrome coronavirus (SARS- COV) infection that later became a threat around the globe. Secondly, the middle East respiration Syndrome coronavirus (MERS- CoV), in the Arabian Gulf region ¹. In December 2019, the brand new coronavirus contamination COVID-19 that emerged from Wuhan has posed a high quality hazard to international health ².

COVID- 19 affects people in different ways. The disease spreads substantially through person to person through the upper respiratory tract or lower respiratory tract. It has plethora of symptoms like high fever, dry cough, breathlessness, muscle pain, anosmia, fatigue, sore throat, agnosia, and anaemia. Neurological symptoms include difficulty in thinking or concentrating, headache, sleep problems and dizziness. Heart symptoms reported were chest pain and palpitation.  These COVID- 19 symptoms may get severe in elderly with comorbidities similar to cardiovascular complaints, pulmonary complaints, and diabetes ³. The pathogenesis is that it attaches to the angiotensin converting enzyme - 2 receptors present on the epithelia of the lung and small intestine with the spike protein and infects the cells which beget covid. The infection has an incubation period of 1 – 14 days, but generally, it takes 3 – 7 days to present symptoms ⁴.

Landsteiner has described the ABO carbohydrate moieties that are genetically inherited and previous studies have suggested a relationship between ABO blood groups with some diseases and microbial infections 5. COVID-19, Plasmodium falciparum, Helicobacter pylori, Norwalk virus, viral hepatitis virus, and Neisseria gonorrhoeae infections have been found to interact with these blood group antigens ^{6, 7}. The molecular mechanisms show that O blood group contains both antibodies A and antibodies B that can inhibit the binding of the virus spike (S) protein to the cell. So it is found that blood group antigen types have an indirect impact to the host susceptibility to infection. Studies have found that individuals with blood group A or B had more incidence of cardiovascular disease or increased chance of a blood clot ⁸. Likewise, recent studies show some association between ABO blood types and the severity of covid illness ^{9, 10}.

The objectives of the study are to determine the prevalence of ABO blood group type in COVID 19 infected patients admitted in the Institute hospital in the mentioned period and find any association among the different ABO blood types and severity of the disease.

It is a retrospective and observational cross-sectional study done at the Department of Transfusion Medicine, from January 2021 to December 2021. All healthy donors blood groups in the specified time period were noted. Blood groups of covid patients admitted were retrieved from the separately maintained registry. Informed consent from patients was obtained and the study was approved by Institutional Ethics Committee (IHEC -I/0623/22,25.01.2022).

All patients admitted to the hospital for covid treatment in the specified period with available blood group report and laboratory parameters.

Only patients with COVID 19 confirmed by nasopharyngeal swab RT-PCR positive were included.

Infection with COVID-19 was found in 527 out of the total patients admitted between 2021 January and 2021 December. Due to the lack of clinical and/or laboratory data, a total of 504 participants were included in the research.

A total of 2318 donors gave blood at the hospital at the specified period, of whom 536 belonged to the O blood group, 434 to the B blood group, 356 to the A blood group, and 102 to the AB blood group.

We evaluated association between blood group types and outcomes using four comparisons (Age, genders, severity and susceptibility).

In the present study we found that prevalence of blood group O was higher than non O blood groups. However there was no association between ABO blood group and severity of the disease.

Zhao et al. were among the first to suggest a possible connection between ABO blood types and SARS-CoV-2 susceptibility in 2020 ¹¹. Since then, several researches have been done in this discipline producing a variety of outcomes, but the majority have found that blood group A individuals have higher predisposition to the infection ^{12, 13}. A meta-analysis pointed that the risk of infection connected to blood types was categorised as follows: A > O > B > AB ¹⁴.

In recent studies of COVID-19 infection in China and the United States, it has been found that ABO blood types have an impact on the infection severity and death, suggesting that the infection is more likely to occur in people with blood group A than in blood group O ^{15, 16}.

These results are consistent with research from the USA that patients with firstly O blood group blood (45.5%) followed by type A blood (34.2%) had greater COVID-19 prevalence ¹⁷; Research from Asia revealed that blood group O (62.4%) patients are more susceptible to COVID-19 ¹⁸. In one another study, Saudi citizens were more likely to have type O blood (62%), compared to those with type A blood (27.6%), type B blood (8.7%), or type AB blood (9%). (1.7%) ^19.

Dzik et al. pointed out that prevalence may reflect the general distribution of the blood group in that region. As in our study, blood group O was predominant in the healthy donor distribution for the selected time period, though statistically not significant. The distribution in a given region varies from time to time and screening of the whole community alone will reflect the region blood group distribution ²⁰.

However, studies from Turkey and China, type A blood had higher prevalence of COVID-19 infection. In Iran, people with the blood type AB are more likely than those with other blood types to get infected with COVID-19 ⁹. No connection was found between blood type and the clinical severity of COVID-19 in a comparable manner 21. The frequency and prevalence of blood groups may have contributed to this difference ²². Blood group A is more susceptible to thromboembolic events. Some studies claim that anti A antibodies in blood group O prevented invasion of S protein thus causing less infection of the covid virus ²³.

In terms of demographic characteristics, another predictor for COVID-19 is gender, and among the 500 patients who tested positive, more men than women (308 men against 196 women, or 61.1% to 38.9% each) were present. In previous studies, male cases outnumbered female cases, developing serious illness.  Although the cause of the COVID-19 prevalence in men was unknown, it has recently been shown that certain comorbidities, such as hypertension, diabetes mellitus, and cardiovascular disease, might indirectly raise the risk of sickness or mortality in men24. However, the COVID-19 incident mortality rate is greater for women than for males in several nations, including Slovenia, Nepal, and Vietnam25.

In order to investigate the connection between blood group and infection severity, we compared the blood group distributions between the entire COVID-19 sample and those who required ICU hospitalisation. Of the 500 COVID-19 patients, 88 patients, or 17.5 %, were admitted to the intensive care unit. From this study, more patients with blood type O had COVID-19 infection admitted to ICU, whilst blood type AB patients had the lowest incidence. Therefore, it highlights that there is no link between blood type and susceptibility to a more serious COVID-19 infection.

The disagreement across research may result from varying sample numbers, ABO variability between people or regions, genetic background variation26. The variability of COVID -19 clinical manifestations may be impacted by variation in blood group characteristics between nation and various genotypes27.

It is difficult to draw a conclusion about a link between blood type and COVID-19 based on the results of the study and the few papers in this sector, which indicate a range of findings. However many suggest that some unidentified underly component, not necessarily the blood group, may be what is creating the connection.

The prevalence of O group Rh positive was higher than other blood groups compared in Covid patients admitted. We also observed that blood group had no association with the outcome of the patient recovery and intubation. Further studies with larger sample size and other Institutional collaborations are needed to establish ABO as a prognostic indicator in COVID 19 infection.

Nil

Nil