Fact Check: 8 Persistent 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, so after it delivers the instructions to your cells, it breaks down and disappears from the body (in about 72 hours). The mRNA never even goes into 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.

Back to top

Myth: The vaccine must not be that effective because you’re still supposed to wear a mask after getting vaccinated.

Truth: The vaccines work extremely well. The Pfizer-BioNTech vaccine was 95% effective in a study involving about 43,000 people. The Moderna vaccine was 94% effective in a study involving more than 30,000 people. The Johnson & Johnson/Janssen vaccine was 85% effective in preventing severe COVID-19 in a study involving more than 44,000 people. But no vaccine provides 100% protection against getting the virus or spreading it to others, which is why it’s very important to continue following safety guidelines such as social distancing, wearing masks, and regularly washing your hands. This is especially true right after you get the vaccine, because it takes time for your immune system to respond and offer protection.

COVID-19 Vaccines Are Safe and Effective; They Do Not Cause Cancer
Learn from MSK infectious disease specialist Elizabeth Robilotti what you need to know about the COVID-19 vaccines.
Back to top

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.

Back to top

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.

Back to top

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. Some people receiving the vaccines have reported 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.

Information for Patients and Caregivers
Learn about our response to COVID-19 and our updated policies to protect our patients and staff.
Back to top

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.

The CDC is carefully tracking all adverse reactions, and they have been rare. As of February 16, more than 55 million vaccine doses have been administered in the US and no concerns for serious adverse events have emerged.

There have been very few cases of a serious allergic reaction called anaphylaxis. It tended to happen in people who already had a history of severe allergies. The overall risk of having a severe allergic reaction is about the same compared to other common vaccines.

Back to top

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

Truth: The CDC notes that pregnant women are at increased risk for severe illness from COVID-19 and recommends this group be given the opportunity to be vaccinated after discussing the risks and benefits with their healthcare provider. None of these vaccines were tested in pregnant or breastfeeding women, although animal studies have demonstrated that the vaccine is safe. The FDA has asked drug makers to study the effects on pregnant or breastfeeding women.

As of February 16, there have been no safety problems reported in a registry of more than 30,000 pregnant women who have been vaccinated.

Back to top

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.

March 2, 2021

Additional Resources

Back to top