Patients with type O and rhesus negative (Rh) blood groups may have a lower risk of severe infection with the coronavirus 2 (SARS-CoV-2) with acute respiratory syndrome and severe coronavirus disease, according to a published study ( COVID-19) in the annals of internal medicine.
The researchers conducted a population-based, retrospective cohort study of 225,556 patients whose ABO blood type was examined between January 2007 and December 2019 and then tested for SARS-CoV-2 between January 15 and June 30, 2020. The mean age was 53.8 years and 29% were men. Frequent comorbidities were pre-existing heart disease (13-15%), chronic kidney disease (11%), anemia (21%), cancer (27-29%), dementia or frailty (33-38%), diabetes mellitus (21%) ), Asthma (18-21%) and chronic hypertension (39-41%).
The primary outcome of the study was SARS-CoV-2 infection. The secondary outcome was severe COVID-19 illness or death. Adjusted relative risks (aRRs) and absolute risk differentials (ARDs) were adjusted for demographic characteristics and comorbidities. For the primary result, the analyzes of patients under 70 years of age versus 70 years of age or older were stratified.
The O blood group had a 2.1% chance of SARS-CoV-2 infection (95% CI, 1.8-2.3%), the lowest unmatched probability of any blood group. The aRR for SARS-CoV-2 infection in the O blood group was 0.88 (95% CI, 0.84-0.92) versus all other blood groups, and the ARD was -3.9 per 1,000 (95% CI) % CI, -5.4 to -2.5). . By comparison, the highest unadjusted probability of SARS-CoV-2 infection was in the B + blood group (4.2%; 95% CI, 4.0-4.5%). The results also showed that the aRR for SARS-CoV-2 infection was higher in patients with AB blood type compared to type A.
Before SARS-CoV-2 infection, the Rh status appeared with an aRR of 0.79 (95% CI, 0.73-0.85) and an ARD of -6.8 per 1,000 (95% CI, – 8.9 to -4.7). The O blood group also appeared to be protective, with an aRR of 0.74 (95% CI, 0.66-0.83) and an ARD of -8.2 per 1000 (95% CI, -10.8 to -5.3). The relative protective effects of O, Rh and O blood groups were greatest in patients under 70 years of age.
The results of the secondary result showed that the type O blood group had an aRR of 0.87 (95% CI, 0.78-0.97) for severe COVID-19 illnesses and deaths compared to all other blood types and the Rh Status an aRR of 0.82 (95% CI, 0.68-0.96) compared to the Rh + status. The O blood group did not seem to protect against severe COVID-19 disease and death (aRR, 0.84; 95% CI, 0.64-1.07) compared to other blood groups.
“Studies on the accuracy of serological tests for anti-SARS-CoV-2 immunoglobulins can assess whether the antibody titers vary depending on the ABO and Rh status,” the authors stated. “Furthermore, in ongoing clinical studies on immunotherapy with convalescence plasma or with SARS-CoV-2 vaccines, the interaction between the participating blood groups and the therapeutic effectiveness could be measured.”
The researchers also suggested further research into how ABO status can mitigate the occurrence of venous thromboembolism, a known complication of COVID-19, as blood type O patients have been associated with a decreased risk of venous thromboembolism in previous studies.
Ray JG, Schull MJ, Vermuelen MJ, Park A. Association between ABO and Rh blood types and SARS-CoV-2 infection or severe COVID-19 disease. Ann Intern Med. Published online November 24, 2020. doi: 10.7326 / M20-4511
This article originally appeared on Infectious Disease Advisor