Vaccine Concerns: Safety and Myth Busting

Vaccines are one of the most important tools in public health for preventing deaths and severe illness. Since 2000, it’s estimated that vaccines have prevented more than 37 million deaths in low- and middle-income countries.¹ Information from the World Health Organization (WHO) estimates that vaccines continue to prevent up to 5 million deaths every year.²

Despite this, the WHO also lists vaccine hesitancy — reluctance to get vaccinated — as one of the top 10 threats to global health. Fears about vaccine safety are a key reason for people choosing not to vaccinate.³

Misinformation and myths can spread rapidly on the internet. This article will address some of the most common myths about vaccines.

Are Vaccines Safe?

In the United States, the Food and Drug Administration (FDA) tests and evaluates each vaccine before it is available to the public. The FDA is a government organization responsible for protecting the public’s health by making sure that all drugs are both safe and effective.⁵

Vaccines go through several steps before they can be approved for use. The first step is laboratory testing, which can take several years. The FDA evaluates the results of laboratory testing before it can move on to the next step — clinical trials in people.⁵

Clinical trials for a vaccine usually start small, with fewer than 100 volunteers. If initial trials find that the vaccine is safe and effective, new clinical trials can begin that include thousands of people. Throughout the process, the FDA works closely with the company developing the vaccine to evaluate the vaccine’s safety and efficacy.⁵

Even after a new vaccine is approved by the FDA, vaccine safety is continually tracked and monitored through regular manufacturing facility inspections and national vaccine monitoring. In the US, there are several systems for tracking vaccine safety, including:⁵

• Vaccine Adverse Events Reporting System (VAERS) — where patients, healthcare providers, and vaccine companies can report serious vaccine side effects
• The Vaccine Safety Datalink (VSD) — where the Centers for Disease Control and Prevention (CDC) uses medical records to track vaccine safety in large populations
• Post-licensure Rapid Immunization Safety Monitoring System (PRISM) — where the FDA uses health insurance claims to find possible vaccine safety issues

Do Vaccines Cause Autism?

Autism is a developmental disorder that affects social communication and interaction. Although researchers don’t know the exact cause of autism, it’s likely caused by a number of different genetic and environmental factors.⁵ Multiple studies have not been able to find a link between vaccines and developing autism.⁶

The myth that vaccines cause autism was started in the 1990s when a doctor named Andrew Wakefield published an article claiming that the measles virus is responsible for autism. He proposed that the measles virus triggered inflammation in the colon. This inflammation allowed toxic proteins to enter the bloodstream from the colon and travel to the brain and cause autism. The article was retracted in 2005 for research misconduct and possibly using false data.⁷

Concerns over vaccine safety were encouraged by the media, who interviewed parents of typically developing children who started developing autism after receiving the measles, mumps, rubella (MMR) vaccine.⁷

This myth has been debunked by several clinical studies. A 2013 study by the CDC found that increased exposure to the immune-stimulating ingredients of vaccines (antigens) in the first two years of life didn’t increase the risk of developing autism.⁸

There have also been concerns over vaccine ingredients being linked to autism. Several studies have investigated a possible link between vaccine ingredients, like the preservative thimerosal and others. No study has found a link between any vaccine ingredient and autism.⁶

Can Vaccines Give You the Disease They Are Supposed to Protect You from?

You may have heard people say that getting the flu shot gives them the flu, but this isn’t possible. Vaccines use weakened or killed versions of disease-causing germs that can’t cause disease, which stimulates an immune response.⁹

However, some of the side effects of vaccines might feel similar to the disease they are protecting against, such as the flu.¹⁰ Usually, these side effects are much milder than the disease and go away after a few days. Side effects are not symptoms of a disease but the result of your body’s immune response to the vaccine.¹¹

Some of the vaccine side effects that might be similar to the disease they are protecting against include:¹²

• Fever
• Headache
• Muscle aches
• Joint pain
• Swollen glands
• Chills
• Nausea
• Tiredness
• Rash

However, in people with weakened immune systems, it may be possible to develop a life-threatening infection after getting a vaccine that uses a weakened version of the germ (called a live vaccine) to stimulate an immune response. Examples of this type of vaccine include:¹³

• MMR vaccine
• Rotavirus vaccine
• Smallpox / monkeypox vaccine
• Chickenpox vaccine
• Yellow fever vaccine
• Polio vaccine

Because of this, it’s generally not recommended to receive a live vaccine if you have a weakened immune system.¹³

Are Vaccine Ingredients Dangerous?

Vaccines use only the ingredients that are needed to make it safe and effective. (Read more about how vaccines are made.) Ingredients in vaccines might include:¹⁴

• Stabilizers — like sugar or gelatin, used to keep the vaccine active
• Adjuvants — like aluminum salts, to boost your body’s response to the vaccine
• Leftover inactivating ingredients — like formaldehyde, used to kill viruses
• Leftover products from cell culture — like egg protein, used to grow the germ to make the vaccine
• Leftover antibiotics — used to prevent bacteria growth during manufacturing
• Preservatives — like thimerosal, are only used in some flu vaccines

You may have negative feelings about some vaccine ingredients, such as mercury or formaldehyde, but extensive testing has found that these ingredients are safe in the amounts used in vaccines.¹⁴

Rumors that some vaccines, like the COVID-19 vaccine, contain microchips or ingredients that can make you magnetic are false. COVID-19 vaccines don’t have any metals or other ingredients that could track your movements.¹⁵

Can Too Many Vaccines Overload Your Immune System?

The CDC recommends vaccinations for 14 different infectious diseases before the age of two. Vaccinating children early ensures that they have some protection from diseases before they’re exposed to them.¹⁶

Multiple clinical studies over the years have found that this schedule is safe and effective for children. While getting multiple vaccines at once may cause some side effects, like fever, it hasn’t been shown to cause any long-term health problems. Additionally, getting more than one vaccine at a time is more convenient because it means fewer office visits.¹⁶

Is Natural Immunity Better Than Immunization?

You may have heard of “chickenpox parties” where parents expose children who have never had chickenpox to a child who is currently infected, with the hope that their child will catch the disease and build immunity while they’re young. This type of immunity is called natural immunity.¹⁷

While it’s true that natural immunity for some diseases may be stronger than the immunity you get from a vaccine, it’s not worth the risk.¹⁸ Even chickenpox, which is usually a mild disease in childhood, carries significant risks with a natural infection, such as:¹⁹

• Bacterial infections
• Pneumonia
• Brain swelling
• Bloodstream infections
• Dehydration
• Death

Serious side effects from any vaccines are very rare — around 1 or 2 people per 1 million doses of vaccine.²⁰ In contrast, the risk of death in children under 14 years old from catching chickenpox is 1 in 100,000.²¹

Other diseases can be even more deadly. Without medical care, 100 percent of people who catch tetanus die. However, just six doses of the tetanus vaccine can give you lifelong protection from this deadly disease.²²

Some vaccines can even be more effective than natural infection, such as:²³

• Human papillomavirus (HPV) vaccine
• Haemophilus influenzae type B (Hib) vaccine
• Pneumococcal vaccine

If Everyone Around Me Is Vaccinated, Do I Need to Be?

It’s true that when most of a population is vaccinated against a disease, even people who are not vaccinated are protected — this is called herd immunity. Herd immunity can help protect the most vulnerable people in a population who may not be able to get a vaccine, including people who are:²⁴

• Too young
• Immunocompromised (have a weakened immune system)
• Pregnant

The percentage of the population that needs to have immunity to a disease to achieve herd immunity differs depending on how easily the disease spreads. A disease like measles, which spreads very easily, needs a larger portion of the population to be immune to reach herd immunity. This also means that smaller decreases in vaccination rates can have a larger effect. Decreases in measles vaccination resulted in a 30% increase in measles cases worldwide in 2019.³

Can Vaccines Alter Your DNA?

New types of vaccines, like messenger RNA (mRNA) and viral vector vaccines, work by giving your cells instructions on how to protect you from the disease. The instructions are contained inside genetic material.¹⁵

However, after your cells get the instructions, the genetic material from the vaccine is quickly broken down and isn’t integrated into your cell’s own genetic material.¹⁵

What if You Still Have Questions?

Talk to your healthcare provider if you still have any questions about vaccine safety or which vaccines you or your child should get. They can answer questions about the potential risks and benefits of each vaccine based on your medical history.