COVID-19 Resource Center

COVID-19 Resource Center

Disclosures: The authors report no relevant financial disclosures.
November 24, 2020
2 min read
Save

Type O, Rh– blood may be linked to lower COVID-19 risks

Disclosures: The authors report no relevant financial disclosures.
You've successfully added to your alerts. You will receive an email when new content is published.

Click Here to Manage Email Alerts

We were unable to process your request. Please try again later. If you continue to have this issue please contact customerservice@slackinc.com.

Having O and rhesus-negative, or Rh–, blood was associated with a slightly lower risk for COVID-19 infection and severe illness or death, according to research published in Annals of Internal Medicine.

The study provides more evidence that blood type may affect risks related to COVID-19 infection and severity.

Photo of blood test tubes
Having O and rhesus-negative, or Rh–, blood was associated with a slightly lower risk for COVID-19 infection and severe illness or death, according to research published in Annals of Internal Medicine. Source: Adobe Stock.

“The uncertainty around ABO or Rh blood groups and SARS-CoV-2 infection persists,” Joel G. Ray, MD, MSc, professor in the department of medicine at the University of Toronto, and colleagues wrote. “Accordingly, this population-based study was done to evaluate SARS-CoV-2 infection and severe COVID- illness in relation to ABO and Rh status.”

Ray and colleagues conducted a population-based, retrospective cohort study of adults and children in Ontario, Canada, who had their blood group assessed from 2007 through 2019 and who were later tested for SARS-CoV-2 using viral RNA polymerase chain reaction testing from mid-January through June.

They used national databases to collect information on SARS-CoV-2 tests, hospitalizations, ED visits, preexisting conditions, demographic information and income.

A total of 225,556 people who had an ABO blood group test and a SARS-CoV-2 laboratory test were included in the study. Of those, 36.3% had type A blood, 4.5% had type AB blood, 14.9% had type B blood and 44.3% had type O blood. Of participants, 13.1% had Rh– status.

Ray and colleagues determined that adjusted relative risk (aRR) for SARS-CoV-2 infection in those with type O blood was 0.88 (95% CI, 0.84-0.92; ARD = 3.9 per 1000; 95% CI, 5.4 to 2.5) compared with A, AB and B blood type.

Additionally, they found that Rh– blood types were protective against COVID-19 infection (aRR = 0.79; CI, 0.73 to 0.85; ARD = 6.8 per 1000; 95% CI, 8.9 to 4.7), with a particularly strong protection in those with O– blood (aRR = 0.74; 95% CI, 0.66-0.83; ARD = 8.2 per 1000; 95% CI, 10.8 to 5.3).

According to the researchers, those with type O blood had a lower risk for severe COVID-19 or death compared with all other blood types (aRR = 0.87; 95% CI, 0.78-0.97; ARD = 0.8 per 1000; 95% CI, 1.4 to 0.2). Compared with those who had Rh-positive blood, those with Rh– blood were also found to have a lower risk for severe COVID-19 or death (aRR = 0.82; 95% CI, 0.68-0.96; ARD = 1.1 per 1000; 95% CI, 2.0 to 0.2).

Based on the findings, Ray and colleagues concluded that type O blood may be linked to a lower risk COVID-19 infection, severe illness or death.

“At most, a small proportion of SARS-CoV-2 infection or related illness in the entire population could be prevented by some undetermined property conferred by O blood type and, perhaps, further enhanced by Rh status,” Ray and colleagues wrote. “Whether this information can influence COVID-19 prevention or treatment strategies remains to be determined.”