Vaccination rates for several diseases including measles, diphtheria and polio, decreased among U.S. kindergartners in the 2024-25 school year from the year before, according to federal data posted on Thursday.

The U.S. Centres for Disease Control and Prevention released the new figures at a time when the country faces a growing measles outbreak, with confirmed cases this month reaching the highest level since the disease was declared eliminated from the country in 2000.

Secretary of Health and Human Services Robert F. Kennedy Jr. has long questioned the safety of vaccines, contrary to scientific evidence, and he has also suggested a link between vaccines and autism.

The CDC data show vaccination rates have steadily trended down since the COVID-19 pandemic. For the measles, mumps and rubella vaccine, coverage went from 95.2% in the 2019-2020 school year to 92.7% last year, before landing at 92.5% in 2024-2025. In Texas, the epicentre of the recent outbreak, MMR coverage has fallen to 93.2% from 96.9% in 2019.

Most people are protected from measles through herd immunity when more than 95% of people in the community are vaccinated, the CDC website says.

An HHS spokesperson said the data released on Thursday showed a “majority” of children continue to get routine childhood immunisations, and that vaccination remains the most effective way to protect children from measles and whooping cough.

“The decision to vaccinate is a personal one,” the spokesperson said. “Parents should consult their healthcare providers on options for their families.”

In addition, exemptions from one or more vaccines increased to 3.6% in 2024-2025 from 3.3% the year before, the CDC website said. Exemptions, which can be granted on medical or religious grounds, increased in 36 states and DC, with 17 states reporting exemptions exceeding 5 per cent, it said.