It’s not just your habits or pre-existing conditions that determine how you’d respond to the novel coronavirus if you were to contract it.

The makeup of your molecular building blocks has a major effect on how severe your illness could be—and research has shown that your blood type could be one of these key genetic indicators.

Recently, a new study confirmed earlier reports that having type A blood puts you at a higher risk of developing severe COVID.

Read on to find out what blood type could protect you from the virus, and for more on how to tell you’re already sick.

The findings come on the heels of continued research from the GenOMICC Consortium, an international association of scientists that study the connections between severe illnesses and genes.

These scientists compared the genes of more than 2,000 COVID-19 patients in Great Britain with those of healthy people, The Washington Post reports.

Initial research from the same team, published in the journal Nature in October, pointed to those with type A blood being more likely to develop serious illness when infected with SARS-CoV-2, while those with type O blood were offered some form of effective protection from the disease.

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“Our genetic data confirm that blood group O is associated with a risk of acquiring COVID-19 that was lower than that in non-O blood groups, whereas blood group A was associated with a higher risk than non-A blood groups,” the authors wrote.

The original study also found a location on chromosome 3 that was linked to respiratory failure and now, other genetic markers that point to how specific people handle infections are becoming clear.

For example, a gene named IFNAR2, which allows cells to build a protein receptor for an immune molecule, can be a measure of how bad one’s COVID battle will be. A weak response could allow the virus to quickly infect and take over a patient’s body.

Despite the potential for major therapies to be developed as a result of the findings, the study’s authors still caution that there’s likely much more to the picture than meets the eye. “A chunk of the answer is in our genes [but] it’s unlikely that a single element is fully responsible for the development of severe COVID-19,” Sara Clohisey, PhD, study author and a researcher at the University of Edinburgh, told The Post. “It’s more likely to be a combination of factors.”

The study authors note that genes likely play in tandem with other known health complications that raise the risk of severe COVID in patients.

Read on to see which conditions increase the likelihood of a serious bout with COVID, and for more on pre-existing conditions that could have the opposite effect on you.

1

Obesity

Person weighing themselves on scale because of weight loss
Person weighing themselves on scale because of weight loss

The Centers for Disease Control and Prevention (CDC) says that obesity is a high-risk factor for severe COVID-19. Research has found that people who are considered obese—which means they have a body mass index, or BMI, of 30 or higher—are more likely to be hospitalized after being infected with the coronavirus than those who are not. And for more symptoms that could mean you’re coming down with COVID.

2

Age

Senior man in home quarantine wearing a mask and looking through the window, during coronavirus COVID-19 epidemic.
Senior man in home quarantine wearing a mask and looking through the window, during coronavirus COVID-19 epidemic.

Although the CDC adjusted its recommendations to broaden its stance on how age plays into your risk of severe COVID-19, the agency maintains that it is still very much a factor. “CDC now warns that among adults, risk increases steadily as you age, and it’s not just those over the age of 65 who are at increased risk for severe illness,” their site says.

3

Diabetes

Man with diabetes pricking finger
Man with diabetes pricking finger

According to the CDC and medical experts around the world, people with type-2 diabetes have been considered among the highest risk for severe cases of COVID-19 since early in the pandemic. In fact, a recent French study highlighted the level of severity individuals with the condition face when infected with coronavirus, finding that 10 percent of patients with diabetes who were hospitalized for severe COVID-19 died within a week of being admitted.

4

Heart disease

Man holding heart while wife helps
Man holding heart while wife helps

The CDC warns that any type of preexisting heart condition may put you at a higher risk of severe COVID-19. But the agency points out that of all conditions, heart failure, coronary artery disease, cardiomyopathies, and pulmonary hypertension are the most concerning.