COVID-19 vaccine myths debunked

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Updated March 30, 2022

As the coronavirus disease 2019 (COVID-19) pandemic continues, you might have questions about COVID-19 vaccines. Find out about the different types of COVID-19 vaccines, how they work, the possible side effects, and the benefits for you and your family.

Let's set the record straight on some of the myths circulating about COVID-19 vaccines.

Myth: The COVID-19 vaccine is not safe because it was rapidly developed and tested.

Fact: Because there is an urgent need for COVID-19 vaccines and the Food and Drug Administration's (FDA's) vaccine approval process can take years, the FDA first gave emergency use authorization to COVID-19 vaccines based on less data than is typically required. The data must show that the vaccines are safe and effective before the FDA can give emergency use authorization or approval.

Vaccines with FDA emergency use authorization or approval include:

Pfizer-BioNTech COVID-19 vaccine

The FDA has approved the Pfizer-BioNTech COVID-19 vaccine, now called Comirnaty, to prevent COVID-19 in people age 16 and older. The FDA approved Comirnaty after data found the vaccine is safe and effective. The Pfizer-BioNTech COVID-19 vaccine is 91% effective in preventing the COVID-19 virus with symptoms in people age 16 and older.

The vaccine is still under an emergency use authorization for children ages 12–15. The vaccine is 100% effective in preventing COVID-19 in children ages 12–15. It requires two shots given 21 days apart. The second dose can be given up to six weeks after the first dose, if needed.

The vaccine is now also available under an emergency use authorization for children ages 5–11. This vaccine is about 91% effective in preventing COVID-19 in children ages 5–11. It requires two shots, given 21 days apart. It also contains a lower dose than the Pfizer-BioNTech COVID-19 vaccine used for people age 12 and older.

Moderna COVID-19 vaccine

The FDA has approved the Moderna COVID-19 vaccine, now called Spikevax, to prevent COVID-19 in people age 18 and older. The Moderna COVID-19 vaccine is 94% effective in preventing the COVID-19 virus with symptoms. It requires two shots given 28 days apart. The second dose can be given up to six weeks after the first dose, if needed.

Janssen/Johnson & Johnson COVID-19 vaccine

In clinical trials, this vaccine was 66% effective in preventing the COVID-19 virus with symptoms — as of 14 days after vaccination. The vaccine also was 85% effective at preventing severe disease with the COVID-19 virus — at least 28 days after vaccination. This vaccine is authorized for people age 18 and older. It requires one shot. If you are given this vaccine, learn about the possible risks and symptoms of a blood-clotting problem.

The Centers for Disease Control and Prevention (CDC) recommends getting a mRNA COVID-19 vaccine over getting the Janssen/Johnson & Johnson COVID-19 vaccine. But getting any COVID-19 vaccine is better than not getting a COVID-19 vaccine.

Myth: I already had COVID-19 and I have recovered, so I don't need to get a COVID-19 vaccine when it's available.

Fact: Getting COVID-19 might offer some natural protection or immunity from reinfection with the virus that causes COVID-19. It's estimated that getting COVID-19 and COVID-19 vaccination both result in a low risk of another infection with a similar variant for at least six months. But because reinfection is possible and COVID-19 can cause severe medical complications, it’s recommended that people who have already had COVID-19 get a COVID-19 vaccine. A recent study showed that unvaccinated people who already had COVID-19 are more than twice as likely as fully vaccinated people to be reinfected with COVID-19.

Recent research also suggests that people who got COVID-19 in 2020 and then received mRNA vaccines produce very high levels of antibodies that are likely effective against current and, possibly, future variants. Some scientists call this hybrid immunity. Further research is needed.

If you were treated for COVID-19 with monoclonal antibodies or convalescent plasma, there is no need to delay getting a COVID-19 vaccine.

Myth: There are severe side effects of the COVID-19 vaccines.

Fact: While many people do not have reactions after vaccination, it is normal if you do. It does not mean you have the COVID-19 infection. It is an indicator that your immune system is responding to the vaccine. If you have a reaction, take some time to rest and allow your body to recover.

A COVID-19 vaccine can cause mild side effects after the first or second dose, including:

Pain, redness or swelling where the shot was given
Fever
Fatigue
Headache
Muscle pain
Chills
Joint pain
Nausea and vomiting
Feeling unwell
Swollen lymph nodes

You'll be monitored for 15 minutes after getting a COVID-19 vaccine to see if you have an allergic reaction.

Most side effects go away in a few days. Side effects after the second dose might be more intense. Many people have no side effects. Side effects of booster shots appear to be similar to side effects experienced after the two-dose or single-dose primary shots. If the redness or tenderness where the shot was given gets worse after 24 hours or you are concerned about any side effects, contact your doctor.

Myth: The COVID-19 vaccines don't work because you can still get COVID after vaccination.

Fact: COVID-19 vaccination will protect most people from getting sick with COVID-19. But some fully vaccinated people will still get COVID-19. These are called vaccine breakthrough infections.

People with vaccine breakthrough infections can spread COVID-19 to others. However, fully vaccinated people with a breakthrough infection are less likely to have serious illness with COVID-19 than those who are unvaccinated. Even when vaccinated people develop symptoms, they tend to be less severe than those experienced by unvaccinated people.

Myth: The current COVID-19 vaccines don't protect against the COVID-19 variants.

Fact: Currently, the Centers for Disease Control and Prevention has identified two variants of the virus (SARS-CoV-2) that causes coronavirus disease 2019 (COVID-19) as variants of concern:

Delta (B.1.617.2). This variant is nearly twice as contagious as earlier variants and might cause more severe illness. The greatest risk of transmission is among unvaccinated people. People who are fully vaccinated can get vaccine breakthrough infections and spread the virus to others. However, it appears that fully vaccinated people spread COVID-19 for a shorter period than do unvaccinated people. While research suggests that COVID-19 vaccines are slightly less effective against the delta variant, the Pfizer-BioNTech, Moderna and Janssen/Johnson & Johnson COVID-19 vaccines still appear to provide protection against severe COVID-19.
Omicron (B.1.1.529) and BA lineages. The B.1.1.529 variant spreads more easily than the original virus that causes COVID-19 and the delta variant. However, omicron appears to cause less severe disease. People who are fully vaccinated can get breakthrough infections and spread the virus to others. But the COVID-19 vaccines are effective at preventing severe illness. This variant also reduces the effectiveness of some monoclonal antibody treatments. Omicron has a few major offshoots (sublineages), including BA.1, BA.2 and BA.3. BA.2 made up about 55% of COVID-19 infections that had genetic sequencing in the U.S. during a week in late March, according to the CDC.

Myth: Most people don’t need a COVID-19 booster shot.

Fact: An additional primary shot of a COVID-19 vaccine is recommended for people who are vaccinated and might not have had a strong enough immune response.

In contrast, a booster dose is recommended for people who are vaccinated and whose immune response weakened over time. Research suggests that getting a booster dose can decrease your risk of infection and severe illness with COVID-19.

People who have a moderately or severely weakened immune system should get an additional primary shot and a booster shot.

The CDC recommends additional primary shots and booster doses of COVID-19 vaccines in specific instances:

Additional dose
The CDC recommends an additional primary shot of an mRNA COVID-19 vaccine for some people with weakened immune systems, such as those who have had an organ transplant. People with weakened immune systems might not develop enough immunity after vaccination with two doses of an mRNA COVID-19 vaccine or one dose of the Janssen/Johnson & Johnson COVID-19 vaccine. An additional shot using an mRNA COVID-19 vaccine might improve their protection against COVID-19.
The additional primary shot should be given at least 28 days after a second dose of an mRNA COVID-19 vaccine or one dose of the Janssen/Johnson & Johnson COVID-19 vaccine
The additional primary shot should be the same brand as the other two mRNA COVID-19 vaccine doses that were given. If the brand given isn't known, either brand of mRNA COVID-19 vaccine can be given as a third dose.
Booster dose
A single booster dose is recommended for people age 12 and older after getting two doses of an mRNA COVID-19 vaccine or one dose of a Janssen/Johnson & Johnson COVID-19 vaccine. You can get a booster if you received:
- Pfizer
  Are age 12 and older and it's been at least five months after completing the primary series. The Pfizer or Moderna booster vaccines are preferred for most people ages 18 and older. Ages 12–17 may only get a Pfizer booster.
  Are age 5–11, it's been at least 28 days after completing the primary series, and you are moderately or severely immunocompromised
- Moderna
  Are age 18 and older and it's been at least five months after completing the primary series
- Johnson & Johnson
  Are age 18 and older and it's been at least two months after receiving the Johnson & Johnson vaccination
The Pfizer-BioNTech or Moderna COVID-19 vaccine boosters are preferred in most situations.

Pregnant women also can get a COVID-19 booster dose.

If you have a weakened immune system, had two doses of an mRNA COVID-19 vaccine and an additional primary shot, and it’s been at least three months since the additional shot, get a single booster dose. An mRNA COVID-19 vaccine is preferred.
Second booster dose
A second booster dose of an mRNA COVID-19 vaccine is recommended for certain people who have a weakened immune system and people age 50 or older. This second booster dose can be given to those eligible four months after a first booster dose of any authorized or approved COVID-19 vaccine.

Myth: People with existing health conditions should not get a COVID-19 vaccine.

Fact: COVID-19 vaccines are safe for people who have existing health conditions, including conditions that increase the risk of severe illness with COVID-19.
People who have a moderately or severely weakened immune system should get an additional primary shot and a booster shot.

Myth: Children can't get severely sick with COVID-19, so they don't need a COVID-19 vaccine.

Fact: A COVID-19 vaccine can prevent your child from getting COVID-19 and spreading it at home and in school.

If your child gets COVID-19, a COVID-19 vaccine could prevent severe illness. Getting a COVID-19 vaccine can also help keep your child in school and more safely have playdates and participate in sports and other group activities.

Myth: I won't need to wear a mask after I get vaccinated for COVID-19.

Fact: You are considered fully vaccinated two weeks after you get a second dose of an mRNA COVID-19 vaccine or two weeks after you get a single dose of the Janssen/Johnson & Johnson COVID-19 vaccine.

You are considered up to date with your vaccine if you gotten all recommended COVID-19 vaccines, including booster doses, when you be eligible.

After getting fully vaccinated, you can more safely return to doing activities that you might not have been able to do because of the pandemic.

However, if you are in an area with a high number of new COVID-19 cases, the CDC recommends wearing a mask indoors in public and outdoors in crowded areas or when you are in close contact with unvaccinated people. If you are fully vaccinated and have a condition or are taking medications that weaken your immune system, you may need to keep wearing a mask.

You also will still be required to wear a mask on planes, buses, trains and other public transportation traveling to, within, or out of the U.S., as well as in places such as airports and train stations.

If you are traveling in the U.S., you don't need to get tested before or after your trip or quarantine after you return. If you are traveling outside of the U.S., you don't need to get tested before you leave the U.S. unless your destination requires it. You still need to show a negative test result or proof that you've recovered from COVID-19 in the past three months before boarding an international flight to the U.S.

If you've gotten all recommended vaccine doses, including boosters and additional primary shots, and you've had close contact with someone who has the COVID-19 virus, get tested at least five days after the contact happens.

Myth: The COVID-19 vaccine was developed to control the general population either through microchip tracking or "nanotransducers" in our brains.

Fact: There is no vaccine microchip, and the vaccine will not track people or gather personal information into a database.

This myth started after comments made by Bill Gates from The Gates Foundation about a digital certificate of vaccine records. The technology he was referencing is not a microchip, has not been implemented in any manner and is not tied to the development, testing or distribution of COVID-19 vaccines.

Myth: COVID-19 vaccines will alter my DNA.

Fact: The first COVID-19 vaccines to reach the market were messenger RNA (mRNA) vaccines. According to the CDC, mRNA vaccines work by instructing cells in the body how to make a protein that triggers an immune response. Injecting mRNA into your body will not interact or do anything to the DNA of your cells. Human cells break down and get rid of the mRNA soon after they have finished using the instructions.

Myth: COVID-19 vaccines were manufactured using fetal tissue.

Fact: Neither the Pfizer/BioNTech nor Moderna vaccines for COVID-19 contain fetal cells, and fetal cells were not used in their development or production.

In two animal studies, researchers performed laboratory testing of the vaccines using historically harvested fetal cell lines. However, both animal studies were conducted after these vaccines were already in phase 3 clinical trials.

Myth: COVID-19 vaccines cause infertility or miscarriage.

Fact: It's recommended that you get a COVID-19 vaccine if you are pregnant or breastfeeding, trying to get pregnant or might become pregnant in the future. There is no evidence that any vaccines, including COVID-19 vaccines, cause fertility problems in men or women.

It's not clear if getting COVID-19 or a COVID-19 vaccine causes changes in menstruation. A new study of about 4,000 people suggest that getting a COVID-19 vaccine is linked with a less than one-day change in menstrual cycle length for each does.

Keep in mind that many things can affect menstrual cycles, including infections, stress, sleep problems and changes in diet or exercise.

Myth: Pregnant and breastfeeding women should not get the COVID-19 vaccine.

Fact: If you are pregnant or breastfeeding, it's recommended that you get a COVID-19 vaccine. The overall risk of COVID-19 to pregnant women is low. However, women who are pregnant or were recently pregnant are at increased risk of severe illness with COVID-19. Getting a COVID-19 vaccine can protect you from severe illness due to COVID-19. Vaccination can also help pregnant women build antibodies that might protect their babies.

COVID-19 vaccines don't cause infection with the COVID-19 virus, including in pregnant women or their babies. None of the COVID-19 vaccines contain the live virus that causes COVID-19. Also, keep in mind that mRNA COVID-19 vaccines don't alter your DNA.

Findings from a study of more than 40,000 women show that getting a COVID-19 vaccine during pregnancy poses no serious risks for pregnant women who were vaccinated or their babies. Most of the women in the study received an mRNA vaccine. (24) In addition, vaccines that use the same viral vector as the Janssen/Johnson & Johnson COVID-19 vaccine have been given to pregnant women in each trimester of pregnancy in clinical trials. No harmful effects were found.

Myth: I am allergic to eggs so I shouldn't get the COVID-19 vaccine

Fact: Neither the Pfizer/BioNTech COVID-19 vaccine nor the Moderna COVID-19 vaccines contain egg nor were eggs used the development or production of either vaccine. However, those with severe allergic reactions to eggs or any other substance (i.e., anaphylaxis) are encouraged to remain after vaccination for 30 minutes for observation.

Myth: COVID-19 vaccines must be stored at extremely low temperatures because of preservatives in the vaccines.

Fact: Pfizer/BioNTech and Moderna have reported that their vaccines contain no preservatives.

Different vaccines have different storage requirements. For instance, the Pfizer/BioNTech vaccine must be stored at minus 94 degrees Fahrenheit (minus 70 degrees Celsius), while Moderna has said that its vaccine needs to be stored at minus 4 degrees Fahrenheit (minus 20 degrees Celsius). Both of these vaccines use messenger RNA, or mRNA, to teach your cells how to make a protein that will trigger an immune response to COVID-19. However, messenger RNA is fragile and can break down easily. Storing messenger RNA vaccines, like these COVID-19 vaccines, in an ultracold environment keeps them stable and safe.

You should not worry about these temperatures. Vaccines are thawed before injection.

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Information in this post was accurate at the time of its posting. Due to the fluid nature of the COVID-19 pandemic, scientific understanding, along with guidelines and recommendations, may have changed since the original publication date.

For the safety of our patients, staff and visitors, Mayo Clinic has strict masking policies in place. Anyone shown without a mask was either recorded prior to COVID-19 or recorded in a non-patient care area where social distancing and other safety protocols were followed.