WASHINGTON — Outgoing GOP Sen. Bill Cassidy laced into President Trump’s executive order last week requiring measles, mumps and rubella (MMR) vaccines to be administered to children separately.

Cassidy (R-La.), a doctor who chairs the Senate Committee on Health, Education, Labor and Pensions (HELP), warned Trump’s executive order will have severe repercussions for children.

“If it wasn’t so potentially tragic, it would break out laughing at a comment like that,” Cassidy told CNN’s “State of the Union” Sunday about Trump’s remark that “nothing bad” can come from his executive order.

“From the perspective of the parent, now, instead of going to the doctor twice to get their child vaccinated, they have to go six times,” he went on before later adding: “There’s a lot of bad things that will come out of this.”

“This has the potential to decrease the protection that a child would receive against diseases which can be deadly.”

The physician, who set up a program to help vaccinate school kids in his native Louisiana, raised concerns that by potentially increasing the number of visits parents have to make to the doctor to get their children vaccinated, costs will rise and the burden of taking more time out of work could mean fewer children get the jabs.

Cassidy, a trained gastroenterologist, has long been at odds with Health and Human Services Secretary Robert F. Kennedy Jr. on vaccines, particularly over the scion’s concerns about possible links to autism, which many medical experts have long disputed.

While signing the executive order, Trump claimed that MMR vaccines — the three-in-one shots against measles, mumps, and rubella — could be “quite lethal” and “sort of like a nuclear weapon.”

The president further bizarrely stated that the vaccine was “the size of a bottle of soda poured into a little child’s body, and bad things happen in many too many cases.”

“Yeah, that’s a crazy, stupid thing,” Cassidy bluntly said of Trump’s remarks on the vaccine.

“The child is going to get more jabs; the parents are going to lose money,” the senator added.

“This is why the president’s poll numbers are going down, because people don’t perceive that he knows the reality of their life.”

Cassidy stressed that the prior system in place was intended to prevent the spread of diseases and maximize convenience for the parents.

The two-shot MMR vaccine — which inoculates children against three preventable childhood viruses — has been the recommended standard in the US since 1989.

Most developed countries, including the UK, Canada and Australia, recommend that young children get a similar two-dose three-vaccine shot.

When asked about whether he regrets voting for Kennedy to be the HHS boss, a decision he agonized over at the time, Cassidy argued that dwelling on that vote is a distraction from what needs to be done now.

Cassidy lost his primary for reelection in May against Trump-endorsed Rep. Julia Letlow (R-La.) The president had been irked by Cassidy’s support for his second impeachment.