People having blood group of A, B and those with Rh factor positive are more susceptible to COVID-19 infection compared to those having O or AB group and Rh negative, according to a new study conducted by doctors at a Delhi hospital.

In a statement issued on Tuesday, Sir Ganga Ram Hospital (SGRH) said the research was conducted on a total of 2,586 Covid-positive patients, tested through real-time PCR (RT-PCR), who were admitted at the facility from April 8 to October 4 in 2020.

The study by the Department of Research and Department of Blood Transfusion Medicine at the SGRH has found that (those having) blood groups A, B and Rh+ are more susceptible to COVID-19 infection whereas (those with) O, AB and Rh- are at lower risk of COVID-19 infection, the statement said.

The researchers have also claimed that there is no association between blood groups, and susceptibility to severity of disease as well as mortality.

Resus factor or Rh factor is a protein that may be present on the surface of red blood cells (RBCs).

The positive or negative sign next to the blood groups is known as the Rh factor. If the blood type is positive, then the blood cells have the Rh protein, and they lack the Rh protein, if negative.

The study has been published in November 21 edition of 'Frontiers in Cellular and Infection Microbiology', the statement said.

Dr. Rashmi Rana, Consultant, Department of Research, SGRH, said, Severe acute respiratory syndrome coronavirus 2 is a new virus, and it is unclear whether blood groups have any impact on COVID-19 risk or progression. Therefore, we investigated the association of ABO and Rh blood group with COVID-19 susceptibility, prognosis, recovery time, and mortality in this study".

During the study of admitted patients, follow-up was also taken up till their last date of admission as either discharged or deceased, hospital authorities said.

According to Dr. Vivek Ranjan, co-author and Chairperson, Department of Blood Transfusion, SGRH, "We also found that male patients of blood group B are more prone to COVID-19 than the female patients with blood group B, and blood group AB was observed to be more susceptible to infection in patients with age group of over 60 years.

The study also claimed that blood group A and Rh + types are associated with a decrease in recovery period, whereas blood group O and Rh- are associated with increase in recovery period, according to the statement.

However, the ABO and/or Rh blood groups may not be responsible for this association, as these may indicate an unexplored underlying factor like co-morbidity. Therefore, larger, multicentre and prospective studies are needed to ascertain the relationship between blood groups and SARS-CoV-2," it added.