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10 Vaccine Myths You Can Safely Ignore

Don't buy into the rumors. Get the vaccine facts from medical experts who debunk the most common misconceptions about childhood and adult vaccines

Cut through vaccine confusion

The modern vaccine got its start back in the late 1700s when Edward Jenner created one for smallpox, and they are generally considered one of the greatest public health inventions of all time. Eventually, scientists developed vaccines for everything from polio to measles, saving millions of lives. Even though this technology has a long history, there still seems to be some confusion and unrelenting myths about vaccines. Read on as experts set the record straight.

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Myth: Vaccines could cause horrible side effects

Fact: Vaccines go through rigorous testing before they become available. While there’s a chance you could have mild side effects like bruising or a day of feeling sniffly, a serious side effect is extremely rare, says Jennifer Lighter Fisher, MD, pediatric hospital epidemiologist at NYU Langone Medical Center. “Vaccines are tested in more children over a longer period of time than any other drug before they’re approved by the FDA,” she says. Anything on the market has been shown to have benefits that should far outweigh any risks. (Don’t skip the human papillomavirus vaccine either—here are HPV myths you shouldn’t believe.)

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Myth: Some diseases are so rare that there’s no point in vaccination

Fact: Diseases like polio and diphtheria might be rare in the United States (because of, yes, vaccination), but they still exist in other parts of the world. “It just takes one unimmunized traveler to bring a disease home from another country,” says Eileen Yamada, MD, public health medical officer with the California Department of Public Health Immunization Branch. “If immunization levels drop, the rare cases we have in America could very quickly multiply, putting our children in danger.” When too many people skip vaccines, it can lead to outbreaks of dangerous and once-rare infections like whooping cough and measles. In 2019, there were nearly 1,300 measles cases in the U.S., the largest number of cases since 1992. The majority of cases were in unvaccinated individuals in an outbreak in New York state, although cases were seen in 31 states. Plus, some people, such as cancer patients and newborns, can’t get vaccines, so getting yourself immunized protects not only you but others in your community, Dr. Fisher says.

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Myth: I shouldn’t bother getting a flu shot because there are so many different strains

Fact: Even if you do pick up a different flu strain from the one in your vaccination, you’ll end up less sick if you got the shot than if you skipped it. “Because there are so many different strains that circulate each year, the efficacy of the flu vaccine is often based on if it’s a good match between the strains of the vaccine and what’s circulating in the local community that year,” Dr. Fisher says. “Even so, getting the flu vaccine will most likely, if you do end up getting the actual virus, it will be more likely to be much less severe because of the vaccine.” Find out mistakes that may be messing with your flu vaccine.


Myth: Children’s immune systems can’t handle more than one vaccine at a time

Fact: Getting several different vaccines at the same time won’t cause any lasting health problems. “Children are exposed to hundreds of viruses and bacteria during normal activities like eating and playing,” says Dr. Yamada. “Getting vaccines is no extra burden on the immune system, even for babies.” Some studies even suggest that the immune system might actually get stronger with a combination of vaccines than getting one at a time, likely because they call for different arms of the immune system that then work together, Dr. Fisher says.

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Myth: You’re more likely to get sick from a vaccine than from the environment

Fact: Vaccines come from killed or weakened germs, or just specific proteins from them, which won’t cause serious illness. To help the body recognize and fight the disease in the future, the immune system will have the same response it would to a real infection, Dr. Yamada says, but the most you’ll get is a minor symptom like a brief fever that’s way less dangerous than anything you’d pick up from your environment. Even if you do feel a bit sick, your sniffles are probably totally unrelated to your shot, Dr. Fisher says. “Often when people get the flu shot, it happens to be in the season when respiratory viruses are starting to circulate in the community,” she says. “So if they get a flu shot and then one of the other common respiratory viruses, they presume it’s from the shot when they probably got a different virus.” (Traveling? Don’t miss the vaccinations and medications you need to know about before you travel.)

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Myth: Vaccines can cause autism

Fact: “That’s absolutely ridiculous,” Dr. Fisher says. The rumor stems from a small, flawed 1998 study that only examined 12 children and didn’t include a control group to pinpoint the cause of their symptoms. An investigation by British medical journal BMJ found that the lead author had altered the kids’ medical histories. The study was later formally retracted by 10 of its 13 original authors, and numerous studies have since found no link between vaccines and autism.

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Myth: Disease rates are dropping because of better sanitation, not vaccines

Fact: Even within the past several decades, the incidence of specific diseases have dropped after vaccines have been introduced, according to the World Health Organization (WHO). No matter how diligent you are about washing your hands, you’re wiping off the germs after exposure, not building immunity. “Although good hygiene is very important to help prevent the spread of disease, the germs that cause disease can continue to make people sick as long as they still exist,” Dr. Yamada says.

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Myth: I have a cold, so I shouldn’t get a vaccine right now

Fact: Vaccines won’t make mild illness any worse. “The immune system is much stronger than people realize,” Dr. Fisher says. Even kids with a low fever, cough, runny nose, ear infection, or mild diarrhea can safely get vaccinated without making their symptoms worse, according to the Centers for Disease Control and Prevention. A chronic health condition or serious disease is a different story, so talk to your doctor if you or your child has a severe health problem.

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Myth: Vaccines will 100 percent guarantee you won’t get sick

Fact: Vaccines aren’t 100 percent effective, but they can be pretty darn close. The childhood vaccines on the CDC’s recommended schedule will protect more than 95 percent of kids who are vaccinated, Dr. Fisher says. For the 1 to 5 percent who doesn’t develop immunity, a second dose will boost the protection to almost 100 percent, she says. If there’s a concern (like if chicken pox is going around in your kids’ school), a doctor can test the antibody response to look into the slight chance it didn’t work. Experts rely on herd immunity to boost protection too. That means that the more people who are vaccinated in the community, the less likely a germ can circulate and make people—both vaccinated and unvaccinated—sick. Check out the reasons why parents––not just children––need to be up-to-date on their vaccines, too.


Myth: Vaccines contain mercury—that’s dangerous!

Fact: Some vaccines do use a preservative called thimerosal, which contains ethylmercury, but there’s been no evidence showing it can cause harm in the low doses you’d find in an immunization. A bigger concern is methylmercury, the poisonous quicksilver that can damage the central nervous system, which is not found in vaccines. The body gets rid of ethylmercury way faster than methylmercury, making it less likely to do damage. Even so, ethylmercury was taken out of childhood vaccines in 2001 to ease any concerns and there are thimerosal-free versions of vaccines for adolescents and adults.

Medically reviewed by Tia Jackson-Bey, MD, on April 23, 2020

Marissa Laliberte
Marissa Laliberte-Simonian is a London-based associate editor with the global promotions team at WebMD’s and was previously a staff writer for Reader's Digest. Her work has also appeared in Business Insider, Parents magazine, CreakyJoints, and the Baltimore Sun. You can find her on Instagram @marissasimonian.