The age and political views of parents may play a role in this choice. Individuals who are most likely to postpone or opt out of vaccines for their kids are Republicans, people who identify with President Trump’s Make America Healthy Again (MAHA) movement, adults under 35 years old, and parents who homeschool their kids, according to survey results reported by KFF, an independent health policy research organization.
Several factors contributing to vaccine hesitancy predate the current Trump administration, says Violeta Rodriguez, PhD, an assistant professor of psychology at the University of Illinois in Urbana-Champaign.
These include widespread misinformation on social media about vaccine safety and mistrust sown by shifting vaccine policies during the COVID-19 pandemic, she says.
“The MAHA movement has also amplified skepticism about vaccine schedules, which can reinforce doubts for parents who are already hesitant,” Dr. Rodriguez says.
Mistrust in Medical Institutions Has Contributed to Doubts About Vaccine Safety
For the survey, researchers interviewed more than 2,700 parents, including more than 1,000 parents with children younger than 6 who have had to make decisions about vaccines in a post-COVID era.
While the survey found few parents believe claims about vaccines that are unsupported by research, there are still many parents who are unsure what to think. With the MMR vaccine for measles, mumps, and rubella, for example, just 9 percent of parents believed the disproven claim that the shot causes autism — but 48 percent said they didn’t have enough information to assess whether this claim is true.
Many parents no longer trust the medical institutions that have traditionally been responsible for promoting vaccines as a safe and effective way to prevent deadly childhood diseases, says Carmel Shachar, MPH, an assistant professor and the faculty director of the Health Law and Policy Clinic at Harvard Law School in Boston.
“In general, trust in our institutions is at an all-time low, and trust in our medical institutions is no exception, especially after the intense experience that was the COVID-19 pandemic,” Shachar says. “MAHA is an expression of the very reasonable desire to have healthy kids and communities, along with the worry that we can’t rely on our institutions to meet that goal.”
Herd Immunity Is Declining in Many Communities
Among the states collecting data on how many children received the MMR vaccine, 67 percent of counties and jurisdictions now have immunization rates below 95 percent — the rate that doctors say is required to protect against an outbreak, called herd immunity, NBC reported.
St. Louis, Missouri, offers a window into how declining vaccination rates might put kids at risk. The percentage of kindergartners in the city who have received all the state-mandated vaccinations plunged from 91.6 percent in 2010 to 75.9 percent in the fall of 2024, per NBC.
This is a dangerously low level of community-wide vaccination that puts kids at risk of death from measles, says John Swartzberg, MD, a professor emeritus of public health at the University of California in Berkeley.
“Measles is the most contagious of all respiratory human pathogens,” Dr. Swartzberg says. “We need to have close to 95 percent of the community immune to prevent outbreaks. The sole reason for this year’s large measles outbreak and four deaths in unimmunized Americans is because community immunity in many parts of the United States has dropped well below this number.”
Low Vaccination Rates Will Lead to More Outbreaks and Preventable Deaths, Experts Say
Unless recent trends in vaccination rates reverse, it’s likely the United States will see more outbreaks of vaccine-preventable diseases like measles and whooping cough, as well as more cases of polio and chicken pox, Rodriguez says.
“Prior to the availability of vaccines, large outbreaks of vaccine-preventable diseases occurred every year with enormous numbers of hospitalized people and many, many deaths,” Swartzberg says. “These diseases also left some people disabled for the rest of their lives,” he says, with polio causing paralysis and measles, in rare cases, resulting in brain damage.
With current vaccination trends, hospitalizations and deaths are most likely among infants too young for shots, children who are immunocompromised, kids with chronic health conditions, families with limited access to medical care, and communities with especially low vaccination rates, Rodriguez says.
“Childhood vaccines are among the safest and most effective tools in medicine,” Rodriguez says. “They protect your child from severe complications such as pneumonia, brain swelling, and paralysis, while also protecting the broader community.”
When vaccines are delayed, children are left vulnerable for longer, especially in areas with low vaccination rates, Rodriguez adds. “Skipping vaccines creates clusters where outbreaks ignite,” Rodriguez says. “Parents who have concerns should speak with their pediatrician, ask every question, and review the strong evidence that vaccines save lives.”