As parents shop for backpacks, No. 2 pencils and sneakers in preparation for the new school year, making sure children are up to date on their vaccinations is on many families’ back-to-class checklists.

This year, many health experts are worried that decisions about vaccination — how many shots to get and when to get them – may be unnecessarily complicated because of an executive order signed by President Donald Trump on Monday that seeks to pare down the number of routine immunizations given to American kids and, in some cases, reformulate them and space them out.

“The president wants to maximize parental choice choices over vaccinations for their children,” a White House official said Monday.

Doctors said the a la carte approach to vaccination spelled out in Trump’s executive order would harm families, rather than help.

“The only thing that I can see is going to happen as a result of the announcement from today is an injection of greater amounts of uncertainty and fear and confusion, where there doesn’t need to be any of that,” Dr. Andrew Racine, president of the American Academy of Pediatrics, said Monday.