Table I.
Main characteristics and results of the studies on the association between ABO blood groups and COVID-19
| Author, year | Country | Study design | Sample1 (n) | Mean age (years) | Gender (M/F) | ABO blood group prevalence (O vs non-O) | Main results |
|---|---|---|---|---|---|---|---|
| Abdollahi, 202023 | Iran | Case-control | Cases: 397 Controls: 500 |
Cases: 58.8 Controls: 48.5 |
Cases: 252/145 Controls: 231/269 |
Cases: 28 vs 72%1 Controls: 38 vs 62% |
Group O subjects have a reduced vulnerability to COVID-19. No association between ABO blood types and COVID-19 severity was observed. |
| Boudin, 202024 | France | Cross-sectional cohort, retrospective | Cases: 1,279 Controls: 409 |
Cases: 282 Controls: 272 |
Cases: 1,112/167 Controls: 354/55 |
Cases: 43.2 vs 56.8% Controls: 46.2 vs 53.8% |
In a large population confined to an aircraft carrier, ABO blood groups were not associated with increase/decrease in risk of SARS-CoV-2. |
| Dzik, 202025 | USA | Case-control | Cases: 957 Controls: 5,840 |
Cases: NR Controls: NR |
Cases: NR Controls: NR |
Cases: 48.6 vs 51.4% Controls: 46.6 vs 53.4% |
No association between ABO distribution and SARS-CoV-2 infection or mortality was observed. |
| Ellinghaus, 202022 | Italy, Spain | Case-control | Cases: 1,610 Controls: 2,205 |
Cases: NR Controls: NR |
Cases: 1,126/484 Controls: NR |
Cases: 37.5 vs 62.5% Controls: 47.8 vs 52.2% |
A protective effect in blood group O as compared with other blood groups was observed. |
| Fan, 202026 | China | Case-control | Cases: 105 Controls: 103 |
Cases: 56.8 Controls: 54.0 |
Cases: 55/50 Controls: 56/47 |
Cases: 21.9 vs 78.1% Controls: 29.1 vs 70.9% |
Females with blood type A were more susceptible to COVID-19. |
| Franchini, 202027 | Italy | Case-control | Cases: 447 Controls: 16,911 |
Cases: 47.7 Controls: 47.1 |
Cases: 385/62 Controls:10,321/6,590 |
Cases: 36.2 vs 63.8% Controls: 43.6 vs 56.4% |
The prevalence of O blood type in convalescent plasma donors recovered from COVID-19 was significantly lower than that observed in healthy blood donors. |
| Gallian, 202028 | France | Cross-sectional cohort, prospective | Cases: 27 Controls: 971 |
Cases: NR Controls: NR |
Cases: NR Controls: NR |
Cases: 22.2 vs 78.2% Controls: 46.1 vs 53.9% |
A lower prevalence of anti-SARS-CoV-2 neutralising antibodies was found in French group O blood donors. |
| Göker 202029 | Turkey | Case-control | Cases: 186 Controls: 1,881 |
Cases: 42 Controls: NR |
Cases: 100/86 Controls: NR |
Cases: 24.8 vs 75.2% Controls: 37.2 vs 62.8% |
The frequency of O blood group was significantly lower in COVID-19 patients compared to controls. Blood group types did not affect clinical outcomes. |
| Latz 202030 | USA | Cross-sectional cohort, retrospective | Cases: 1,289 Controls: 6,359 |
Cases: NR Controls: NR |
Cases: 427/862 Controls: NR |
Cases: 45.5 vs 54.5% Controls: 48.3 vs 51.7% |
ABO blood type was not associated with disease severity. O blood group subjects were less likely to test positive for COVID-19 than AB and B groups. |
| Leaf, 202031 | USA | Case-control | Cases: 2,033 Controls: 3.1 m |
Cases: 622 Controls: NR |
Cases: 1,297/736 Controls: NR |
Cases: 46.7 vs 53.3% Controls: NR |
O blood type was a protective risk factor for severe COVID-19 in white race individuals. No association was found with the risk of death. |
| Li, 202032 | China | Case-control | Cases: 2,153 Controls: 3,694 |
Cases: NR Controls: NR |
Cases: NR Controls: NR |
Cases: 25.7 vs 74.3% Controls: 33.8 vs 66.2% |
People with blood group O had a significantly lower risk of SARS-CoV-2 infection. |
| Wu, 202033 | China | Case-control | Cases: 187 Controls: 1,991 |
Cases: NR Controls: NR |
Cases: NR Controls: NR |
Cases: 21.9 vs 78.1% Controls: 30.2 vs 69.8% |
Individuals with group O had a lower risk of COVID-19 than non-O blood group subjects. |
| Yaylaci, 202034 | Turkey | Cross-sectional cohort, prospective | Cases: 397 Controls: NR |
Cases: 47.2 Controls: NR |
Cases: 176/221 Controls: NR |
Cases: 27.5 vs 72.5% Controls: NR |
No relationship was found between blood groups and mortality or ICU admission. |
| Zhang, 202035 | China | Cross-sectional cohort, retrospective | Cases: 134 Controls: 3,694 |
Cases: 60.8 Controls: NR |
Cases: 87/47 Controls: NR |
Cases: 19.2 vs 71.8% Controls: 33.8 vs 66.2% |
A lower infection rate was observed among group O subjects. There was no significant difference in ABO blood type distribution between survivors and non-survivors. |
| Zhao, 202036 | China | Case-control | Cases: 1,775 Controls: 3,694 |
Cases: NR Controls: NR |
Cases: NR Controls: NR |
Cases: 25.8 vs 74.2% Controls: 32.2 vs 67.8% |
Individuals with group O had a higher risk and those with group A a lower risk for SARS-CoV-2 infection. |
| Ray, 202038 | Canada | Population-based cohort, retrospective | Cases: 225,556 Controls: NR |
Cases: NR Controls: NR |
Cases: 65,566/159,820 Controls: NR |
Cases: NR Controls: NR |
The O and Rh- blood groups may be associated with a slightly lower risk for SARS-CoV-2 infection and severe COVID-19 illness. |
| Ziezt, 202039 | USA | Cross-sectional cohort, retrospective | Cases: 2,394 Controls: 10,657 |
Cases: NR Controls: NR |
Cases: NR Controls: NR |
Cases: NR Controls: NR |
A slightly increased infection prevalence among non-O types was found. Risk of intubation was decreased among A and increased among AB and B types, compared with type O. |
| Muniz-Diaz, 202041 | Spain | Case-control | Cases: 854 Controls:75,870 |
Cases: 452 Controls: 452 |
Cases: 338/516 Controls:39,014/36,856 |
Cases: 41.5 vs 48.5% Controls: 47.3 vs 42.7% |
ABO blood group is associated with susceptibility to acquire SARS-CoV-2 infection and with COVID-19 severity and mortality. |
| May, 202040 | USA | Cohort, retrospective | Cases: 165 Controls: NR |
Cases: 57 Controls: NR |
Cases: 61%/39% Controls: NR |
Cases: 43 vs 57% Controls: NR |
ABO blood group did not influence outcomes of patients with COVID-19. |
| Levi, 202037 | Brail | Cross-sectional cohort, retrospective | Cases: 2,037 Controls:1,813,237 |
Cases: NR Controls: NR |
Cases: NR Controls: NR |
Cases: 44.8 vs 55.2% Controls: 46.5 vs 53.5% |
ABO blood group types did not significantly impact the risk for SARS-CoV-2 infection. |
| Barnkob, 202042 | Denmark | Cohort, retrospective | Cases: 7,422 Controls:466,232 |
Cases: 522 Controls: 502 |
Cases: 32.9% men Controls: 32% men |
Cases: 38.4 vs 61.6% Controls: 41.7 vs 58.3% |
ABO blood group is a risk factor for SARS-CoV-2 infection but not for hospitalisation or death from COVID-19 |