The US president announced that his administration will recommend a new vaccination schedule for children: certain vaccines split into five smaller, separate injections, given at six-month intervals. The justification is that this would dramatically reduce the number of autism cases.

Science has had a clear answer to that for twenty years. No serious study has found a link between vaccines and autism.

Dr Paul Offit, director of the Vaccine Education Center at Children's Hospital of Philadelphia, dismissed the proposal briefly. Cutting the dose while increasing the number of injections, he explained, does not make a vaccine safer - it makes it ineffective. "What he is proposing would not work," Offit said. "Essentially he wants vaccines given in a way that offers no protection at all."

He also rejected the claim that vaccines overload a child's immune system. A child's daily immune response, he pointed out, is far greater than anything a single vaccine carries. The idea that vaccines overwhelm immunity and cause chronic illness, he concluded, is a fabrication.

This is not the first time

In August an executive order with a similar intent was signed, and at that point splitting the measles, mumps and rubella vaccine into three injections was proposed - again with no scientific basis. The standard dose of that vaccine is 0.5 millilitres, roughly a tenth of a teaspoon.

Standing beside the president at the event was Health Secretary Robert F. Kennedy Jr. The day before, Kennedy had been greeted with applause at a conference of an anti-vaccine organisation, where he told the audience they had "a strong and unwavering friend" in the White House.

That is the part worth remembering. This is not an error in reading data - it is a policy with the backing of the man who decides public health for 340 million people.

And decisions like this do not stay in one country. Vaccine scepticism travels faster than any vaccine, and it usually settles only after the return of some disease we thought we had long forgotten. How many new excuses will parents who were already wavering now get?