Your Blood Type Might Impact How Susceptible You Are To Norovirus—Here’s How

Here’s what you need to know about how norovirus plays favorites.

Meet the experts: Amesh Adalja, MD, is a senior scholar at Johns Hopkins Center for Health Security who studies emerging infectious diseases. Patricia Foster, PhD, is a Professor Emerita of Biology at Indiana University Bloomington. Mahesh Polavarapu, MD, is the medical director of emergency medicine at NewYork-Presbyterian Westchester Hospital.

Here’s why norovirus is so contagious.

Also known as “the perfect pathogen,” norovirus is pretty effective at getting people sick. Norovirus can be contracted through eating food that’s been contaminated with the virus, or through touching a surface that’s been infected—like a table, railing, or bathroom door handle—and then touching your mouth, says Patricia Foster, PhD, a professor emerita of biology at Indiana University Bloomington.

One of the ways that it spreads is through a common (and gross) symptom: projectile vomiting, which is one sure-fire way for the virus to spread out, says Foster. Bathrooms are often a big source of contamination, adds Mahesh Polavarapu, MD, the medical director of emergency medicine at NewYork-Presbyterian Westchester Hospital.

Beyond that, the virus can outlive alcohol-based cleaners (such as hand sanitizer) and can survive on surfaces for months, per the Mayo Clinic. Plus, it doesn’t take a high viral load—or, the amount of virus in your body—for you to get sick, says Dr. Polavarapu. Because the virus evolves so rapidly, having it once doesn’t provide much long-term immunity. And it also doesn’t help that there’s not a vaccine for norovirus yet.

People with Type O blood may be more susceptible to norovirus.

If you have type O blood, you may be more susceptible to current strains of norovirus than people with type A, B, and AB blood. Those with type O blood have receptors in their GI tract that are preferable to certain strains of the norovirus, making it easier for them to catch the bug. “[For] patients that have type O blood, it’s just easier for the norovirus pathogen to cling on to areas where it can infect them, such as their gut,” says Dr. Polavarapu. (BTW, a whopping 43 percent of Americans have type O blood, meaning it’s the most common blood type in the country, according to the Red Cross.)

The first study to establish this connection between type O blood and norovirus susceptibility was published in The Journal of Infectious Diseases in 2002, and studies published since then have confirmed the link. (Sorry, type O readers.) Meanwhile, one review in Viruses in 2019, found that people with type B blood have a lower susceptibility to norovirus, but the jury is still out on whether that’s accurate. A subsequent 2020 review in Infection, Genetics, and Evolution found that between A, AB and B blood types, no type in particular had an edge when it came to protection.

One thing these studies all have in common? That people with type O blood were constantly the most at risk, says Dr. Polavarapu.

O-typers, don’t freak out just yet: Keep in mind that these trends could change based on the strain of the virus. “When we say that O [is] more susceptible, that’s based on the prevalent strains that are circulating now, or have been for several years. But there are certain strains where that propensity to infect O people more commonly may not hold,” says Dr. Adalja.

Plus, having type O blood also doesn’t automatically mean you’re going to get norovirus; after all, it’s a contagious virus and pretty much everyone is at risk of getting it, says Dr. Polavarapu. Whether or not you come down with the illness is based upon a whole myriad of factors, including your amount of exposure, preexisting health conditions, and age.

A genetic mutation also impacts your susceptibility.

Some good news: The mutation of one specific gene, called FUT2, can help protect a lucky minority of the population from norovirus. And, you can have the mutation even if you have type O blood.

This gene controls the secretion of the H antigen, which the norovirus often binds to when infecting someone, says Dr. Adalja. Those without a functioning FUT2 gene—which is an estimated 15 to 20 percent of people, often called “non-secretors”—are historically less susceptible to norovirus than those with a functioning FUT2 gene, per a 2019 review in Viruses.

But, unlike blood type, secretor status is probably not something you know about yourself. You’d need to do genetic testing (think: 23andMe) to figure out if you’re a non-secretor or not. Foster notes that there are no bad consequences to having this gene—it’s pretty much a win-win.

Still, remember that this gene mutation doesn’t make anyone immune to getting norovirus, and the trend could change as different strains of the illness emerge. “Blood group and secretor status have some influence, but they’re not the complete controlling factor,” says Dr. Adalja.

How To Protect Yourself From Norovirus—No Matter Your Blood Type Or Genetics

No one is built to sidestep norovirus infections completely. Avoiding the illness often comes down to good hygiene practices, like washing your hands with warm water for at least 20 seconds and disinfecting surfaces with a chlorine solution. It’s also important to stay away from people who are sick and avoid sharing bathrooms with infected people if you can.

If you do come down with the virus, make sure you stay hydrated, and let whatever needs to leave your body…leave your body. Though it isn’t glamorous, this is what’s going to decrease your viral load and help you feel better, says Dr. Polavarapu. If you’re feeling very dehydrated or you have persistent high fevers, it’s important to seek medical attention.