Does Blood Type Affect Your Risk For Covid? Key Facts

Early in the pandemic, headlines claimed your blood type might determine your COVID-19 risk. The short answer is that blood type does appear to play a small role in COVID-19 susceptibility and severity, but it is far less important than factors like age, vaccination status, and underlying health conditions. Research has found that people with Type O blood may have a slightly lower risk of infection, while those with Type A might have a modestly higher risk of severe illness if infected. These differences are real but small — your blood type is not something you can change, and it should not guide your personal health decisions.

What Does the Research on Blood Type and COVID-19 Show?

Several large studies have looked at whether blood type affects COVID-19 risk. A 2020 study published in the New England Journal of Medicine found that people with Type O blood had about a 12% lower risk of testing positive for COVID-19 compared to other blood types. The same study found that Type A blood was linked to a 45% higher risk of severe illness requiring respiratory support.

A separate analysis from the COVID-19 Host Genetics Initiative, a global research consortium, confirmed these findings using data from hundreds of thousands of patients. They found that the ABO gene region — which determines your blood type — was among the genetic factors linked to COVID-19 susceptibility. However, the effect was modest. Your blood type explains only a tiny fraction of your overall risk.

The largest study on this topic, published in Blood Advances in 2022, analyzed data from over 100,000 people. It found that Type O blood was associated with a 14% lower chance of infection and a 13% lower chance of severe illness or death. Type A blood showed a 6% higher risk of infection and an 8% higher risk of severe outcomes. These numbers are consistent across multiple independent research groups, which strengthens the evidence.

How Does Blood Type Affect Your Immune Response to COVID-19?

The biological reasons behind these differences are not fully understood, but scientists have several working theories. Blood type antigens are not just on your red blood cells — they are also present on the surface of your respiratory tract cells. These are the same cells that the SARS-CoV-2 virus uses to enter your body.

One leading theory is that people with Type A blood produce more of a protein called ACE2, which acts as a receptor for the virus. More ACE2 receptors could mean the virus has an easier time infecting cells. Research from the University of Kentucky found that the spike protein of the virus binds more tightly to cells from people with Type A blood than to cells from Type O blood.

Another theory involves antibodies. People with Type O blood naturally produce anti-A and anti-B antibodies. Some researchers believe these antibodies may partially block the virus from entering cells. This is still a hypothesis — not a proven mechanism. The CDC has not issued any guidance based on blood type, which tells you how small the effect likely is.

Does Blood Type Affect Your Risk for Long COVID?

Evidence on blood type and long COVID is less clear. A 2023 study from the University of Exeter found that people with Type A blood were more likely to report persistent symptoms like fatigue and brain fog three months after infection. However, the study was small — only about 1,500 participants — and relied on self-reported symptoms, which can introduce bias.

Other research has found no link between blood type and long COVID. A large analysis from the UK Biobank, which tracks health data on 500,000 people, did not find a significant association between ABO blood type and the risk of developing long COVID symptoms. When studies disagree like this, it usually means the effect — if it exists — is very small.

One reason for the mixed results is that long COVID is not a single condition. It likely represents several different biological problems, including ongoing inflammation, tissue damage, and autoimmune responses. Blood type might influence one of these pathways but not others. As of 2026, no major health organization recommends considering blood type when assessing long COVID risk.

How Much Should You Worry About Your Blood Type?

Very little. The risk differences between blood types are small compared to other factors. The CDC states that the strongest predictors of severe COVID-19 are age — risk increases sharply after age 50 — and underlying medical conditions like obesity, diabetes, heart disease, and chronic lung problems. Vaccination status is also a major factor. Unvaccinated adults have a much higher risk of hospitalization than vaccinated adults, regardless of blood type.

To put the numbers in perspective: if your blood type is Type A, your risk of severe COVID-19 is about 8% higher than average. If you are over 65, your risk of severe COVID-19 is about 400% higher than someone under 40. Blood type is a rounding error compared to age.

Here is a quick comparison of the major risk factors for severe COVID-19:

Source data from CDC and NIH. These are approximate figures based on large population studies.

What Should You Actually Do Based on This Information?

Nothing. Your blood type is fixed from birth and cannot be changed. Unlike weight, blood pressure, or vaccination status, it is not something you can modify to reduce your risk. The practical takeaway is simple: do not let your blood type give you a false sense of safety or danger.

Some people with Type O blood might feel less motivated to get vaccinated or wear masks. That would be a mistake. The protection from being Type O is tiny compared to the protection from vaccination. Conversely, people with Type A blood should not panic. The increased risk is small, and you can offset it entirely by staying up to date on vaccines and following standard precautions.

Here are the actions that actually matter for reducing your COVID-19 risk, ranked by strength of evidence:

• Get vaccinated and boosted. This is by far the most effective step. Vaccines reduce severe illness risk by over 90% in most age groups.
• Wear a high-quality mask in crowded indoor spaces. N95 or KN95 masks filter out 95% of airborne particles.
• Improve indoor ventilation. Open windows, use HEPA air purifiers, or upgrade HVAC filters to MERV-13.
• Stay home when sick. Even mild symptoms can spread the virus to vulnerable people.
• Manage underlying conditions. Keeping blood pressure, blood sugar, and weight in healthy ranges reduces severe illness risk.

Common Misconceptions About Blood Type and COVID-19

One myth that circulated widely was that people with Type O blood are completely immune to COVID-19. This is false. The research shows a reduced risk, not zero risk. People with Type O blood have been infected, hospitalized, and died from COVID-19. The difference is about 12-14% lower risk, not 100% lower.

Another myth claimed that blood type determines how well vaccines work. There is no good evidence for this. A 2022 study in Clinical Infectious Diseases looked at antibody levels after vaccination across all blood types and found no meaningful differences. Everyone produces strong immune responses regardless of their ABO type.

A third misconception is that you can change your blood type through diet or supplements. This is not possible. Blood type is determined by genetics. No food, herb, or lifestyle intervention has ever been shown to alter your ABO blood type. Claims to the contrary are not supported by any credible evidence.

Some people also believe that the Rh factor — whether you are positive or negative — matters for COVID-19. The research here is even weaker than for ABO types. A few small studies suggested Rh-negative people might have slightly lower risk, but larger analyses have not confirmed this. As of 2026, the consensus is that Rh status is not a meaningful factor.