Two medical studies have suggested that people with blood type O may be at lower risk of contracting COVID-19.

A Danish study, conducted by 11 researchers based on the information of 473,654 individuals tested for COVID-19, found that those in blood group O were associated with a decreased risk of coronavirus infection.

"We demonstrate that blood group O is significantly associated with reduced susceptibility to SARS-CoV-2 infection," said the study published Wednesday on Blood Advances, a peer-reviewed medical journal of the American Society of Hematology.

The research indicated that individuals with blood types A, B and AB were also at higher risk of exhibiting thrombosis – the clotting of blood inside a blood vessel – and cardiovascular diseases, which are significant co-occurring conditions among hospitalized COVID-19 patients.

Similar results were found by a Canadian medical study conducted by 14 researchers based on data collected from intensive care unit patients in six metropolitan Vancouver hospitals.

"COVID-19 patients with blood group A or AB appear to exhibit a greater disease severity than patients with blood group O or B," found the study, which was published in the same journal, adding that individuals with blood group O were reported to be "less susceptible to SARS-CoV-2 infection."

The study also noted that COVID-19 patients of blood group A or AB had a higher risk of requiring mechanical ventilation and longer duration in intensive care, compared to those with blood group O or B.

While 84% of patients with blood groups A or AB required mechanical ventilation in SARS-CoV-2 infection, that level was 61% for patients with blood types O or B, according to the research.

The median length of stay in intensive care units was 13.5 days for patients with A or AB blood types, while it was only nine days for patients with O or B blood types, the study found.

Previously, a research carried out by the DNA genetic testing company, 23andMe, on over 750,000 participants, suggested the same results. According to the study, those who had Type O blood, which included high-risk front-line health care workers, were about 13% to 26% less likely to contract the virus after being exposed to it – less than any other blood group. The same group was also 9% to 18% less likely to test positive for COVID-19 if they did get infected.

The number of COVID-19 cases in the world stood around 38.5 million and deaths close to 1.1 million on Thursday, according to Johns Hopkins University data.