6 Myths About Vaccines — and the Truths Behind Them

For starters, do they make you sick?
vaccine bottles

As a primary care physician, I get a lot of questions about vaccines.

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As important as vaccines have been in medicine — from virtually eradicating certain diseases to boosting our yearly immunity from the flu — people still have a lot of misconceptions about them. Below, I’ve set out to clear up the biggest ones I hear from patients.

Myth 1: Once you’re an adult, you don’t need vaccines anymore

Truth: Although many vaccines come during childhood, others are important for adults.  For example, some vaccines — such as tetanus, diphtheria and pertussis — require boosters over time to remain effective. Others, including the flu vaccine, come as frequently as every year. No matter your age, be sure to ask your doctor during your annual well-check about which vaccines you have received in the past and which ones you might need. For example, the Centers for Disease Control and Prevention might recommend specific immunizations if you’re traveling abroad.

“If we stop vaccinating children, we put them and future generations at risk for the same catastrophic diseases our ancestors suffered from.”

Kathryn Teng

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Kathryn Teng, MD

Center for Personalized Healthcare

Myth 2:  If you receive a vaccine, you’re automatically immune

Truth: Vaccines are highly effective — but that doesn’t mean they’re 100 percent effective for everyone. According to the U.S. Department of Health and Human Services, most vaccines are about 90 percent to 100 percent effective in creating immunity. But keep in mind everyone’s immune system is different. Some people may not achieve full immunity.

Myth 3: Getting a vaccine will make me sick

Truth: Vaccines work by boosting your immune system in case you face a certain disease or infection. During this process, they may cause mild symptoms or pain, but they do not cause the actual illness from which they are protecting you. However, vaccines can cause serious allergic reactions in some people, although it is very rare. For most patients, the benefits — and even mild discomfort — of vaccination outweigh the harms of developing the diseases themselves.

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Myth 4: New vaccines are dangerous

Truth: Before a vaccine becomes available to patients, it goes through rigorous research and testing to make sure it is safe and effective. Vaccines, like medications, are highly regulated in the United States and must go through clinical trials before they become available to the general public. Regulation is not foolproof and can’t prevent unforeseen events, but clinical trials are the best assurance we have that a vaccine is safe.

Myth 5: You can’t get any vaccines while pregnant

Truth: It’s true that if you’re planning to get pregnant, it’s a good idea to make sure your vaccines are up-to-date beforehand. However, some vaccines are indeed safe during pregnancy, including tDap (for tetanus, diphtheria and pertussis) and the flu vaccine, which are actually recommended during pregnancy. But pregnant women should not receive the MMR or varicella vaccines. Be sure to talk to your doctor about vaccinations if you are pregnant or planning to be.

Myth 6: If a disease has been eradicated, your children don’t need to be vaccinated against it

Truth: Because of vaccines, certain diseases, including measles, have been eliminated in many locations — but not everywhere. Some of these diseases may still exist in other areas.  Therefore, if people, especially children, are not vaccinated, we start to see these diseases popping up again. Vaccines work because of “herd immunity.” If most people are immune to a disease, then those who are either too young or unable to be vaccinated for various reasons still get some protection because the people around them are immune. If we stop vaccinating children, we put them and future generations at risk for the same catastrophic diseases our ancestors suffered from.

The only exception to this is smallpox. Smallpox has been eradicated worldwide, so children in the U.S. no longer need to receive the vaccination. 

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