Some parents in Colorado are uncertain about the safety and necessity of vaccines given to their children. They also question how the vaccines are timed.

I am a sociologist who has spent nearly two decades studying how parents make vaccine decisions for themselves and their families.

I have interviewed dozens of Colorado parents, as well as pediatricians, researchers and policymakers, and observed vaccine clinics, educational events for parents and providers, and meetings of groups that distrust vaccines. I have delved into the complex and often contradictory information parents get from online discussions, media coverage and official documents.

Rather than objecting to all vaccines in all circumstances, parents in Colorado have told me they value independence. They feel they know their children better than physicians or the experts who create vaccine schedules. They insist their decisions reflect the unique needs of their own child, leading them to space vaccines or opt out of the ones they don’t feel comfortable with.

President Donald Trump seemed to have these kind of parents in mind when he signed an Aug. 10, 2026, executive order on vaccines, which includes a call for the components of the combined measles, mumps and rubella vaccine, commonly known as the MMR vaccine, to be given separately rather in combination.

While it sounds as if the executive order offers more flexibility, it may actually make it harder for parents to exercise choice and customize vaccines.

Limits of executive orders

At the signing, Trump made the unsubstantiated claim that MMR vaccines given in combination could be “quite lethal.” He said giving children each component of the vaccine separately would be “not at all lethal but just very effective.”

The executive order offers a symbolic gesture, not an implementable policy. But it speaks to parents’ long-standing fears about vaccines, even though the idea that giving vaccines one at a time is safer lacks a strong scientific basis.

The CDC recommends children get one dose of MMR at 12-15 months of age and a second dose at........

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