Answers to FAQs about Vaccines

How are Vaccines Tested and Monitored for Safety?

Since vaccines are administered to otherwise healthy people, they are among the most rigorously tested and safest medical products on the market. Did you know it can take 10 or more years and millions of dollars to thoroughly test a new vaccine before it is licensed and made available to the public?

Before being approved for administration, vaccines undergo thorough testing by their manufacturers, the U.S. Food and Drug Administration (FDA), and the FDA’s Center for Biologics Evaluation and Research. Clinical trials are performed before the vaccine is made available, to confirm the vaccine’s safety and efficacy – both as an individual vaccine and when it is given with other vaccines according to the recommended vaccine schedule. Even after the vaccine receives FDA-approval, post-licensure studies are conducted on an ongoing basis to continually monitor the vaccine’s safety and to detect and respond to any rare adverse events.

The CDC and FDA also monitor and evaluate the safety of vaccines through the Vaccine Adverse Event Reporting System (VAERS), the Vaccine Safety Datalink (VSD), and the Clinical Immunization Safety Assessment (CISA) Project. VAERS is a national vaccine safety surveillance program that invites healthcare providers, along with anyone who believes that they or someone they know experienced a vaccine side effect, to file a report. VAERS collects and analyzes these reports, thereby helping scientists identify any new vaccine safety concerns and ensuring that the benefits of vaccines continue to be far greater than the risks. The VSD is a collaboration between CDC and nine healthcare organization. When new vaccines are recommended in the U.S. or if there are changes in how a vaccine is recommended, the VSD helps to monitor the safety of these vaccines. The VSD also conducts studies based on questions or concerns about vaccine safety raised from the medical literature and VAERS reports. And finally, CISA is a national network of vaccine safety experts that help to address any unmet vaccine safety clinical research needs of the U.S.

Today, because of the great efforts that go into ensuring the safety and efficacy of approved and recommended vaccines, the United States has the safest, most effective vaccine supply in its history.

View the Journey of Your Child’s Vaccine Infographic.

Do Vaccines Have Side Effects?

As is the case with any medication, vaccines can have side effects. However, the majority of vaccine side effects are mild, such as soreness where the vaccine was given or a low-grade fever, and go away within a few days. Serious side effects following vaccination – like a severe allergic reaction – are very rare.

In general, parents should pay extra attention to their children’s health for a few days after vaccination. If you notice something that concerns you, call your child’s doctor. But when deciding whether to vaccinate, remember that the diseases from which your child is being protected are very dangerous to their health and while a fever and fussiness is never easy for your baby, it means that the vaccine is working by tricking the body into creating an immune response that may last a lifetime.

What are the Ingredients in Vaccines?

Vaccines are made up of antigens, which are small amounts of the bacteria or virus against which your child is being vaccinated. Antigens are the parts of the vaccine that encourage your child’s immune system to create antibodies that will help prevent future infections. It’s important to note that the antigens in vaccines are from bacteria or viruses that are weakened or killed, so they cannot cause serious illness.

Like many of the foods we eat and drink, small amounts of other ingredients may be added to the vaccine to improve its effectiveness and to keep it sterile. Sometimes a child may be sensitive to one of the components of a vaccine, and an allergic reaction may result. For this reason, you should discuss any allergies your child may have with your healthcare provider.

While a series of accusations have been made over the years regarding the ingredients used in some vaccines, these claims are misinformed and are often taken out of context, or are plainly incorrect. To learn more about some of the ingredients found in vaccines and their purpose, click here.

Why Does My Child Need So Many Vaccines at Once?

The Centers for Disease Control and Prevention’s (CDC) recommended immunization schedule for children is specific, and with good reason. Vaccines are recommended for very young children because this is when they are most vulnerable to serious, life-threatening diseases. The recommended schedule is designed to protect children by providing immunity early in life, before they are exposed to these diseases.

Delaying children’s vaccinations only increases the time that children are susceptible to vaccine-preventable diseases. If a baby is not too young to get the disease, he or she is not too young to get the vaccine.

Did you know that although children are vaccinated against more diseases now than ever before, the number of antigens in vaccines has decreased significantly? (Antigens are parts of bacteria or viruses that cause the body’s immune system to start working.) Thirty years ago, children were only vaccinated against eight diseases, and the total number of antigens was a little more than 3,000. Today, children receive vaccines that protect against 14 diseases, but the total number of antigens in these vaccines is only about 150. Vaccines contain just enough of the “antigens” that help your child’s immune system recognize the virus or bacteria so her body can respond if it ever comes in contact.

In fact, the amount of antigens that children fight every day (2,000-6,000) is much more than the antigens in the whole vaccination schedule (150). So children’s immune systems are not overwhelmed by vaccines.

How Can I Be Confident that Vaccines Do Not Cause Autism?

Vaccines do not cause autism. Nearly a dozen studies conducted worldwide over the last decade have failed to find a connection between autism and childhood vaccines. In fact, the original, singular study that claimed to find a connection has been officially retracted by the publication when it was found the lead author, Dr. Andrew Wakefield, lied about his findings. He has since lost his license to practice medicine.

Both the medical and public health communities that monitor vaccine safety have heard the claims of a vaccine-autism link, researched them extensively, and repeatedly disproved them. We encourage you to look at the body of evidence yourself.

Where Can I Read the Research?

Read more about the science behind the safety and efficacy of vaccines here.

Are My Child’s Vaccines Covered Under My Insurance?

No child should miss immunizations due to an inability to pay for the vaccines. There are several programs available to families who can’t afford to pay for vaccines. These include the Vaccines for Children Program (VFC), the Children’s Health Insurance Program (CHIP) and the Affordable Care Act (ACA). In fact, immunizations are one of the only medical interventions specifically covered under the ACA. Due to their tremendous cost-saving attributes, all vaccines recommended by the CDC’s Advisory Committee on Immunization Practices (ACIP) are covered under the Act. Therefore, a person with health insurance should be able to receive an ACIP-recommended vaccine without having to pay a co-pay or deductible.

Learn more about the VFC and ACA on the Every Child By Two website.

Additional Resources

Fact or Fiction: Addressing Parents’ Top Vaccination Questions

Immunization Resources for Parents and Parents-to-Be (2017 edition) booklet

Recursos de vacunación para las mujeres embarazadas y los padres (Edición 2017)

What is Herd Immunity?

Too Many Vaccines? What You Should Know (CHOP)

Vaccine Ingredients: What You Should Know (CHOP)

Common Vaccine Safety Concerns (CDC)

Vaccine Safety: The Facts (AAP)

How Do Vaccines Work? (AAP)

Vaccines for Children Program: Information for Parents from CDC

Preventive Care Benefits for Children (ACA)