American Academy of Allergy, Asthma & Immunology
https://www.aaaai.org/tools-for-the-public/conditions-library/allergies/vaccine-myth-fact
Myth: Vaccines contain many harmful ingredients.
Fact: Vaccines contain ingredients that enable safe administration.
Thimerosal: No US vaccines contain thimerosal or mercury.
Thimerosal was used in influenza vaccines as a preservative in the past. There is no evidence that the compound causes any harm, but the additive has been discontinued as of 2025.
Formaldehyde is present in some vaccines as an inactivating agent, but in much lower amounts than you are exposed to in daily life when you use household products, cough drops, mouthwash, or antihistamines. You also come in contact with formaldehyde in carpets, furnishings, felt-tipped markers, paint, and cosmetics.
Aluminum: added to boost and strengthen immunity to the vaccine. Not all vaccines contain aluminum, but those that do typically contain aluminum in amounts much less than what the average person consumes in a day from foods, drinking water, and medicines.
Myth: Vaccines cause autism and sudden infant death syndrome (SIDS).
Fact: Vaccines are very safe, and reactions to vaccines are infrequent. Most vaccine reactions are usually temporary and minor, such as a fever or sore arm. You are far more likely to be seriously injured by a vaccine-preventable disease than by a vaccine. For example, polio can cause paralysis, measles can cause encephalitis (inflammation of the brain) and blindness, and some vaccine-preventable diseases can even result in death. The benefits of vaccination greatly outweigh the risks, and without vaccines, many more injuries and deaths would occur.
Science has not yet determined the cause of autism and SIDS. These diagnoses are made, though, within the same age range in which children receive their routine immunizations. The 1998 study that raised concerns about a possible link between measles-mumps-rubella (MMR) vaccine and autism was retracted by the journal that published it because it was significantly flawed by bad science. There is no evidence to link vaccines to the cause of autism or SIDS.
Myth: Vaccine-preventable diseases are just part of childhood. It is better to have the disease than become immune through vaccines.
Fact: Vaccine-preventable diseases have many serious complications that can be avoided through immunization.
For example:
Influenza: more than 226,000 people are hospitalized each year with influenza-related complications, including 20,000 children.
Pertussis (Whooping Cough): There have been over 25,000 cases this year in the U.S., with some childhood deaths. Pertussis is becoming drug-resistant.
Measles: There have been almost 2000 cases of measles in the U.S. in 2025, and some children have died. This is a big increase from what we used to see when almost all kids were vaccinated.
COVID: Thousands of children are hospitalized for COVID each year.
Polio: Was almost eliminated worldwide, but is making a comeback. Before there were vaccines, there were up to 3000 deaths each year from polio, and 15,000 people became crippled each year in the U.S.
Myth: I don’t need to vaccinate my child because all the other children around them are already immune.
Fact: Herd immunity occurs when a large portion (95%) of a community is immunized against a contagious disease, reducing the chance of an outbreak. Infants, pregnant women, and immunocompromised people who cannot receive vaccines depend on this type of protection. However, if too many people rely on herd immunity to prevent infection by vaccine-preventable diseases, herd immunity will soon disappear.
Herd immunity for measles has not been achieved in the U.S., and only 73% of children in New Mexico are up to date on the measles vaccine (which also covers mumps and rubella). The number of children vaccinated for whooping cough in NM is even lower.
Myth: A child can actually get the disease from a vaccine.
Fact: A vaccine causing complete disease would be extremely unlikely. Most vaccines are inactivated (killed) vaccines, which makes it impossible to contract the disease from the vaccine. A few vaccines contain live organisms, and when vaccinated with live vaccines, it could lead to a mild case of the disease. Chickenpox vaccine, for example, could cause a child to develop a mild rash. This isn’t harmful and can actually show that the vaccine is working.
Myth: You can get COVID-19 from the vaccine.
Fact: All of the current COVID-19 vaccines approved for use in the United States do not contain the live virus, which means you cannot contract COVID-19 from these vaccines. Like the flu vaccine, a person may contract the disease after being vaccinated if exposed to the virus. These two vaccines are not quite as effective as vaccines like measles, mumps, rubella, whooping cough, tetanus, and hepatitis B (all nearly 100% effective), but still save lives because vaccinated people usually get a milder form of the disease.
Myth: There are microchips in the COVID-19 vaccine.
Fact: There are no microchips in the COVID-19 vaccines currently on the market or under investigation. The vaccines are not tracking people or gathering their information in any way, shape or form.
Myth: The COVID-19 vaccines were not tested before approval. (This is the unedited answer that appears in the article. I can simplify if we decide to use this one)
Fact: There are basically two aspects to vaccine testing. The first test is whether or not the vaccine is safe. The second test is how effective the vaccine is at preventing disease or preventing a severe course of the disease. Many people were surprised and suspicious about how quickly vaccines for COVID-19 were developed. However, the scientific community has many years of experience in designing and testing vaccines, including those for previous coronaviruses similar to the one that causes COVID-19. Therefore, scientists had a very good idea where to begin in developing the various COVID-19 vaccines currently available and those still undergoing testing. The relatively rapid development of vaccines was no surprise to the experts in the field. All COVID-19 vaccines currently available in the United States have been thoroughly tested for safety and effectiveness in preventing disease.
Testing the safety of a vaccine is a complicated process, much of which happens well before the first person is injected. It is first tested in laboratories in tissue culture and animals (in a very humane way). Once the vaccine has been proven safe in animals, researchers begin vaccinating human beings. During this stage, the researchers examine how effective the vaccine is at preventing the disease. The participants are also closely monitored for any side effects- this includes ANYTHING that happens to them, from allergic reactions to tripping on a rug. Human trials are done in 3 phases. During phase 3, thousands of volunteers are tested. Once the vaccine is proven to be effective in preventing the disease and associated with none or only minor side effects, it is then approved for vaccinating larger groups of people. Side effects are monitored throughout all phases of testing and even after vaccine approval is obtained. You can obtain additional information on the vaccine development process here.
Myth: Since I already had COVID-19 and recovered, I do not need to be vaccinated.
Fact: Natural immunity after being ill with COVID may not last long. The combination of natural and vaccine immunity, called hybrid immunity, provides a much stronger defense when exposed to the virus later, and vaccinated people are much less likely to end up in the hospital. Keep in mind that the COVID-19 virus mutates constantly, so the vaccines are updated regularly.
