On Monday, Donald Trump signed an executive order containing new recommendations on vaccines, calling for spacing out their administration to children, and he repeatedly mentioned autism while presenting the text.

Medical research has never established a link between autism and vaccinations, but the US president and his Secretary of Health, Robert F. Kennedy Jr., continue to suggest that there might be one.

"Decades ago, children received only a small fraction of the vaccines required today. At the time, people were much healthier and of course, the high rate of autism that we see today did not exist," Donald Trump said, for example, in the Oval Office, where he mentioned this neurodevelopmental disorder several times.

"We don't know" what causes autism, he admitted.

The American president spoke of injections "the size of a soda bottle" that would be administered to children in the United States, without providing any details on this incredible comparison.

The text also recommends separating, in particular, the vaccines against measles, rubella and mumps, instead of administering them in one injection, Donald Trump said.

His decree also recommends waiting until adolescence for the hepatitis B vaccine.

The federal government, not having the authority to make direct decisions on vaccines, is also content to advise US states to review mandatory vaccines for attending schools, according to the Washington Post, which was able to consult the decree before it was signed.