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Vaccines are safe even for people with an allergy to eggs. Getty Images

Between the measles outbreaks and unpredictable flu season this year, it’s become clear that a small but growing population isn’t keeping up with vaccinations.

So clear, in fact, that the World Health Organization (WHO) has named vaccine hesitancy one of the top 10 global health threats to address in 2019.

While there are several factors that may cause someone to refuse a vaccine, health and safety concerns — including severe adverse and allergic reactions — are one of the main reasons people go unvaccinated, previous research suggests.

However, severe allergic reactions to vaccines or anaphylaxis are incredibly rare and shouldn’t be a source of vaccine hesitancy, according to a new paper published in the Canadian Medical Association Journal (CMAJ) on Monday.

In fact, you’re actually more likely to be struck by lightning this year than to have a severe allergic reaction to a vaccine.

The article features five facts about vaccine allergies and sheds light on the fact that most people probably aren’t allergic to vaccines. And even if they are allergic, there are ways an allergist can safely administer the vaccine.

“There’s a perception that allergy and potential anaphylaxis to vaccine is common, which is making people worried,” the article’s co-author Dr. Zainab Abdurrahman, a pediatric clinical immunologist and allergist at McMaster University, said in a CMAJ podcast that accompanied the article.

“I think these misconceptions may be fueling some of that vaccine hesitancy based on the lack of understanding of the fact that vaccine allergy is extremely rare,” she added.

The odds you’ll have a severe allergic reaction or anaphylaxis to a vaccine is about 1 in 760,000.

To put that into perspective, your chance of being struck by lightning this year is a little higher at 1 in 700,000.

Anaphylaxis, or severe allergic reactions, are unpredictable and occur within minutes of receiving a vaccination. Reactions are unlikely to occur after 30 to 60 minutes after being vaccinated, and are highly unlikely to occur after four hours.

“Hives, swelling — not at the injection site but distant areas like in the mouth, lips, eyelids — and wheezing all indicate a systemic reaction,” says Dr. Richard Rupp, a professor of pediatrics and director of the Sealy Institute for Vaccine Sciences at the University of Texas Medical Branch.

That being said, sometimes hives, rashes, and wheezing may be caused by some other event and may simply coincide with the vaccination, according to Rupp.

Some people may experience fever, chills, muscle aches, and a headache anywhere between 7 to 21 days after vaccination.

Although these side effects are often mistaken for an allergy, they don’t mean you’re having an allergic reaction. Rather, they indicate your body is building an immune response against the disease.

“Vaccines work by activating the immune system, and as a result the immune system becomes stimulated once it’s given. Fever, local pain, and swelling are signs that the immune system is reacting to the vaccination,” says Dr. Tania Mucci-Elliott, an allergist-immunologist with NYU Langone Health.

In the case of the flu, you can’t get the illness from the injected vaccine itself. If you do experience any of these side effects, doctors recommend drinking lots of fluids and taking a pain reliever.

In the past, individuals with severe egg allergies were cautioned to avoid vaccines with egg products.

However, most vaccines no longer contain egg products or have extremely small amounts.

“The amount of egg ovalbumin in vaccines is less than 1 microgram per dose, which should not cause a reaction in even the most severely egg allergic patients,” Dr. Kathleen Dass, an allergist-immunologist with the Michigan Allergy, Asthma & Immunology Center, explained.

The Centers for Disease Control and Prevention (CDC) recommends receiving the flu shot even if you have an egg allergy. There are also two types of influenza vaccines that are now manufactured without eggs that are available for patients 18 years and older, Dass said.

The one exception here is the yellow fever vaccine. This shot contains enough egg protein to trigger an allergic reaction, according to the Children’s Hospital of Philadelphia.

Some people may be allergic to the rubber stopper on the vial or syringe rather than the vaccine itself.

Most manufacturers have moved away from latex rubber stoppers and now use synthetic rubber-like materials, according to Dass. Still, if you have a latex allergy, it’s important to tell your physician. They can check the packaging label and use a latex-free syringe if need be.

Others could be allergic to the gelatin or yeast ingredients that are commonly used in vaccine. That being said, allergies to these components are very rare.

In most cases, an allergist can safely immunize those who have a vaccine allergy.

“If someone has suspected anaphylaxis to a vaccine, allergists will always start by seeing if we can identify the exact cause of the reaction, such as a vaccine component rather than the vaccine itself,” Dass explained.

This involves a skin prick or a blood test, which can help differentiate a true allergy versus a side effect.

If you have a vaccine allergy, the vaccine can be given as a graded dose — or a little bit at a time — under direct medical supervision.

If you experience signs of a severe reaction after getting vaccinated, visit an emergency room immediately. Use an EpiPen if you have one, and elevate your legs to stimulate blood flow to your heart, Mucci-Elliot advised.

If left untreated, anaphylaxis can be life threatening.

Lastly, all significant adverse and allergic reactions should be reported to the CDC’s Vaccine Adverse Event Reporting System to help track and monitor any safety issues with U.S. vaccines.

Vaccine allergy is so rare that you’re more likely to be struck by lightning this year than have an allergic reaction to a vaccine. Now, physicians hope that by debunking the myth that vaccine allergy is common, they can help people make smarter decisions about getting vaccinated.