US Secretary of Health and Human Services Robert F. Kennedy Jr. (R) looks on as President Donald Trump speaks before signing an executive order calling for more research and flexibility on vaccines, in the Oval Office of the White House in Washington, DC, on August 10, 2026.

The World Health Organisation warned Wednesday that US President Donald Trump’s bid to overhaul child vaccination in the United States went against “decades of evidence.”

Trump signed an order on Monday pushing for a rethink of school vaccine mandates and repeating calls for the measles, mumps and rubella vaccine to be separated into three separate shots.

His Health Secretary Robert F. Kennedy Jr founded an anti-vaccine group and has long promoted a disproven link between the MMR shot and autism.

But WHO Director-General Tedros Ghebreyesus said the science is “unequivocal: vaccines — including the MMR vaccine — are safe and do not cause autism.”

“Vaccination policy should be guided by rigorous, independent and transparent review of the best available science, not by political influence,” he warned in a post on X.

He said that the WHO is “concerned that recent changes to US immunisation policy are not aligned with decades of evidence.”

Tedros said that “vaccines provide the strongest protection, how many doses are needed, and which vaccines can be given together safely.

“That evidence is reviewed continuously as new data emerge from across the globe.”

– Major measles outbreak –

The WHO chief also warned that “delaying vaccines or separating doses unnecessarily does not make vaccination safer and can leave children unprotected.”

Trump’s vaccine order came as the US is suffering its worst measles outbreak in 35 years with children across the country readying to return to school, which is likely to further spread infections.

The president said he was pulling the US out of the WHO after 77 years on his first day back in office in 2025.

Medical research has never established any link between autism and vaccination, but sceptics including Kennedy continue to suggest that there might be one.

Kennedy has launched a major review of vaccines, including some that have been in use for decades, overhauled the child vaccination schedule, and cut funding for the development of new vaccines — measures that have been strongly condemned by the medical and scientific community.

Tedros reassured parents on X that “vaccines are among the most powerful tools” to keep children safe, making deadly diseases preventable.”

US courts earlier this year suspended a shake-up of vaccination policy he had initiated.

AFP