Stanford scientists say that vaccine hesitancy has continued to grow amid Robert F. Kennedy Jr’s appointment as secretary of the U.S. Department of Health and Human Services (HHS), with potential negative effects on public health.
While vaccine hesitancy isn’t a new hurdle for healthcare officials, the COVID-19 pandemic and skepticism surrounding COVID vaccines have heightened the problem. The rise of medical misinformation during the pandemic has driven political polarization over vaccines and the broader healthcare world, which persists today.
Kennedy, who was confirmed to lead HHS on Feb. 13, previously led the Children’s Health Defense from 2015 to 2023, which has become a prominent voice in the anti-vaccine movement and a source of false information about vaccines, specifically regarding debunked links to autism.
David Vu, a clinical professor and pediatrics infectious disease specialist, said that political voices have begun to affect how individuals view matters of public health.
“Anything that is health-related, any vaccines, any kind of intervention, has the potential to become a polarizing topic in this political environment,” Vu said.
According to professor of pediatrics infectious disease Yvonne Maldonado, the COVID pandemic has affected how people view vaccines, fueling mistrust and fear toward them. Vu said that during the roll-out of COVID-19 vaccines, a mass of conflicting messages opened the door for medical misinterpretation.
“As a healthcare provider, one of the things that I have to acknowledge is that I think that our messaging has not been optimal,” Vu said. “I think we’ve allowed for mixed messages from a variety of political entities to affect public health.”
However, many healthcare professionals felt threatened to remain silent during the pandemic. Hayley Gans, a clinical professor of pediatrics infectious diseases, said that Stanford Children’s Health faced threats and insults at the height of the pandemic.
“The scientific community was pretty silenced by fears for their safety, and so you kind of saw a void of the scientific voice and evidence,” Gans said. “Yet the other side of things, the misinformation side, actually was loud and clear to people.”
As the COVID pandemic enters the past, many people have already solidified their views on vaccines and their effects, whether positive or negative, affecting public health.
“We have not figured out a way to recover our message,” Gans said.
Loud voices perpetuating misinformation have already begun to affect nationwide vaccination rates. Measles vaccination rates across the nation have dropped, leading to a rise in outbreaks.
Last year saw the largest number of measles cases since the 2019 outbreak, with 285 reports nationwide, 15 of which occurred in California.
Herd immunity against infectious diseases helps prevent larger outbreaks, like a measles outbreak, Maldonado said. Herd immunity against measles generally forms when 95% of a population is vaccinated. However, the rise in measles cases has been coupled with falling vaccination rates.
Measles, mumps and rubella (MMR) vaccination rates in kindergartens have continued to drop nationwide from 95.2% in the 2019-2020 school year to 92.7% in 2023-2024. In the Bay Area, high vaccination rates against MMR have continued.
Gans said that populations in the Bay where percentages are lower are often correlated with homeschooling, independent study or private school programs.
The California Department of Public Health (CDPH) reported that in the 2023-24 school year, immunization requirements were not required for admission at eight public schools with kindergarten and five with seventh-grade across Santa Clara County.
In addition, over 10% of immunization requirements in these schools were overdue, meaning that students missed the recommended timeline to receive a specific vaccine. Of the kindergarten classes, 50% had MMR immunization rates below 95%, with some reaching as low as 80%.
During his welcome ceremony on Feb. 18, Kennedy vowed to investigate the current childhood vaccine schedule. This came after U.S. Senator Bill Cassidy voted to send Kennedy’s nomination to the Senate floor based on the commitment that Kennedy would not alter the federal vaccine schedule.
“We’re yet to see what’s going to happen, but the potential is huge,” Gans said about Kennedy’s recent confirmation.