Data from the Centers for Disease Control and Prevention show the current U.S. vaccine supply is the safest in history.

As children get ready to head back to school, the subject of vaccination is often front and center. In recent years, a growing number of parents have questioned the safety of vaccinations, however scientific research has debunked many of these concerns.

On Wednesday, the CDC reported that more than 100 cases of measles have been diagnosed this year in 21 states and the District of Columbia. The majority of cases affected people who were unvaccinated. The World Health Organization reports that measles is one of the most deadly of all childhood rash/fever illnesses, so why would parents choose to not vaccinate against it?

One concern raised by parents relates to autism spectrum disorder, for which about 1 in 68 U.S. children has been diagnosed. A 1998 study by British researchers involved only 12 children and made the claim that the measles-mumps-rubella, or MMR, vaccine caused autism, however countless studies since have found no evidence of a link.

A 2015 study published in the Journal of the American Medical Association found no harmful association between the MMR vaccine and autism spectrum disorder, even among children already at higher risk for the disorder.

“Although a substantial body of research over the last 15 years has found no link between the MMR vaccine and autism spectrum disorders, parents and others continue to associate the vaccine with ASD,” the report said. “Parents cite vaccinations, especially MMR, as a cause of ASD and have deferred or refused vaccinations for their children as a result. Lower vaccination levels threaten public health by reducing both individual and herd immunity and have been associated with several recent outbreaks of measles, with most cases occurring among unvaccinated individuals.”

Measles was declared eliminated from the United States in 2000, but some outbreaks in recent years have been attributed to communities with declining vaccination coverage. One CDC report of a 2017 outbreak in Minnesota cited “the challenge of combating misinformation about the MMR vaccine and the importance of creating long-term, trusted relationships with communities to disseminate scientific information in a culturally appropriate and effective manner.”

The U.S. Department of Health and Human Services cites polio as one of the great impacts that vaccines have had in the United States. Polio was once America’s most-feared disease, but thanks to vaccination, there are no reports of polio in the U.S.

Benefits outweigh minor risks

Vaccines are medicines, all of which can cause a reaction, but research shows reactions caused by vaccines are typically minor.

The CDC reports that some children can have more serious reactions, but serious reactions are extremely rare. Life-threatening allergic reactions to substances in vaccines, for example, occur once in every million vaccine doses, the CDC reports.

Before a vaccine is approved by the FDA, “results of studies on safety and effectiveness of the vaccine are evaluated by highly trained FDA scientists and doctors,” according to the CDC’s website. “FDA also inspects the sites where vaccines are made to make sure they follow strict manufacturing guidelines.”

When parents have access to accurate online clinical information about vaccines and to vaccine experts, their attitudes improve about vaccinating their children, according to a Kaiser Permanente study, published in May in the American Journal of Preventive Medicine.

“It is certainly understandable that some parents have concerns about vaccinating their children, because there is a lot of misinformation out there, especially on social media platforms. It is clear there is a need to address parents’ concerns in a convenient, user-friendly forum that they trust,” said Matthew F. Daley, MD, senior investigator at the Kaiser Permanente Colorado Institute for Health Research.

The study team created a website that presented easy-to-understand information about the risks and benefits of vaccination and recommended vaccination schedules, vaccine ingredients, and vaccine laws. A social media component also included an expert-moderated blog, discussion forum, chat room, and “Ask a Question” portal, where parents could ask experts about vaccines.

Parents who were hesitant about vaccinating their children had a significant reduction in concerns after accessing to these tools. If you’re worried about vaccination safety or want more information about vaccines, including vaccination schedules for your children, visit cdc.gov/vaccines/index.html.