Fact Check: 7 Myths about COVID-19 Vaccines

Anesthesiologist Anoushka Afonso receiving a COVID-19 vaccine.

MSK anesthesiologist Anoushka Afonso receives a COVID-19 vaccine from clinical nurse Janine Guerra.

Myth: The mRNA vaccines change your DNA and could cause cancer.

Truth: None of the vaccines interact with or alter your DNA in any way, and therefore cannot cause cancer.

Messenger RNA (mRNA) is not the same as DNA and cannot be combined with DNA to change your genetic code. Here’s now mRNA vaccines actually work:

The mRNA vaccines use a tiny piece of the coronavirus’ genetic code to teach your immune system how to make a protein that will trigger an immune response if you get infected. The mRNA is fragile and it delivers the instructions to your cells to make antibodies against SARS-CoV-2. The mRNA does not enter the nucleus of the cell — the part that contains your DNA.

Therefore, there is no truth to the myth that somehow the mRNA vaccine could inactivate the genes that suppress tumors.

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Myth: If I’m not at risk for severe COVID-19 complications, I don’t need the vaccine.

Truth: Healthy people can develop severe COVID-19 infection. Even though they are at a lower risk for severe COVID-19 complications, they can contract and spread the virus. Getting vaccinated protects you as well as your community.

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Myth: The vaccines were developed too quickly. We can’t be sure they are safe.

Truth: COVID-19 vaccines were developed rapidly compared with earlier vaccines because scientists, doctors, and government agencies all over the world invested massive resources to cut red tape and publish results as soon as they were available.

As of December 9, 2021, more than 200 million Americans have been fully vaccinated and the CDC continues to track all adverse reactions.

COVID-19 Vaccine Safety and Effectiveness

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Myth: Getting immunity naturally is safer than getting it from a vaccine.

Truth: The amount of natural immunity a person gets after an infection varies from person to person. Early evidence suggests that natural immunity may not last very long, according to the Centers for Disease Control and Prevention (CDC). Developing immunity from the vaccine is less risky than developing immunity naturally because there’s no way to predict the severity of your symptoms if you get COVID-19.

We expect that when 70% of the population has either received the vaccine or been infected, we will reach what is called “herd immunity,” meaning the chances of the virus still circulating are very low. Waiting until this number is reached naturally — without vaccinating the public — will keep COVID-19 around for much longer.

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Myth: Getting vaccinated will make me sick.

Truth: The vaccine does not contain any live or inactive portion of the COVID-19 virus. It will not cause you to test positive on a test that looks for active COVID-19 infection. You may experience mild to moderate side effects, including pain at the injection site, fatigue (feeling tired), headache, and muscle pain. Not everyone gets side effects. But if you do, they are normal and a sign your body is building up its defenses against the virus.

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Myth: The vaccines aren’t safe for people who are pregnant or are trying to get pregnant.

Truth: There is strong evidence that the vaccines are safe and effective for pregnant women. An August 2021 study showed no increased risk for miscarriage for people who received the mRNA vaccine during the first 20 weeks of gestation.

A study in June 2021 in the New England Journal of Medicine found no safety concerns among more than 35,000 pregnant people who received the Pfizer-BioNTech COVID-19 vaccine (Comirnaty®) or Moderna COVID-19 vaccine (Spikevax™).

The American College of Obstetricians and Gynecologists issued a statement emphasizing that “all eligible persons […] including pregnant and lactating individuals, receive a COVID-19 vaccine or vaccine series.” The Society for Maternal Fetal Medicine also encourages people who are pregnant or breastfeeding to get vaccinated.

COVID-19 Vaccines Are Safe and Effective for People Who Are Pregnant or Breastfeeding

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Myth: The death toll from COVID-19 is exaggerated. It includes people who were already sick with other conditions.

Truth: In a report from the CDC on deaths due to COVID-19, researchers found COVID-19 can directly and indirectly lead to mortality. People with underlying conditions like diabetes or obesity are at higher risk for contracting COVID-19 than those without preexisting conditions. It is true that a person’s preexisting condition may have contributed to their death from COVID-19. However, if the person had not contracted the virus, it is unlikely their preexisting condition would have led to their death. The death toll from COVID-19, in fact, is likely higher than what current numbers indicate. People who die from COVID-19 without being tested, for example, may not be included in current counts.


December 9, 2021


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