Sean O’Leary, M.D., M.P.H., who leads Colorado Chooses Vaccines, responded to the recent announcement by Health and Human Services Secretary Robert F. Kennedy Jr. regarding proposed changes to the U.S. childhood vaccine schedule. The federal plan would shift recommendations to align with Denmark’s schedule, reducing the number of vaccines advised for children.
O’Leary expressed concern about this move, stating: “Today, Health and Human Services Secretary Robert F. Kennedy Jr. announced plans to alter the U.S. childhood vaccine schedule to align with Denmark’s. This will result in fewer recommended vaccines and other changes that will expose more U.S. children to risks from vaccine-preventable diseases.”
He emphasized that there is no evidence supporting benefits from skipping or delaying certain vaccines in the United States, nor any scientific reason to consider Denmark’s approach safer. “There is no evidence that skipping or delaying certain vaccines would benefit U.S. children, and no scientific reason to believe Denmark’s recommendations are safer. When a child goes without recommended immunizations, they are vulnerable to preventable diseases — some of which can be severe, life-threatening, or have lifelong consequences. Measles, whooping cough, and influenza outbreaks demonstrate the risks,” O’Leary said.
O’Leary also noted differences between countries in terms of disease risk, health systems, available vaccines, and timing of childhood health visits: “U.S. parents shouldn’t wholesale follow another country’s immunization recommendations. Different countries face different disease risks, have different health systems, offer different vaccines, and have varying schedules for childhood health visits. Those differences matter because vaccine schedules are designed not in isolation, but as part of a broader system of care. You can’t copy/paste public health.”
He explained that Danish experts base their decisions on local data and conditions just as U.S.-based groups do: “The expert groups that make recommendations in Denmark do so based on their country’s data, disease patterns, and health infrastructure — just as we do here in the U.S. If changes to our schedule are needed — and over the years, we have made updates when the evidence supported it — they should come from careful scientific review. That process is deliberate by design, because the stakes for children’s health are high.”
O’Leary defended the current U.S. vaccine program as effective at preventing serious illness among children: “The U.S. childhood vaccine schedule protects children from serious and sometimes deadly diseases. Every vaccine, and every recommended dose, is timed to work best with a child’s developing immune system and to provide protection when children are most at risk.” He added that vaccination has prevented millions of illnesses and associated burdens for families.
Addressing concerns about misinformation around vaccination policy debates he stated: “Parents are hearing a lot of information right now — much of it confusing and misleading. Our role as physicians is to cut through that noise and share what the science actually shows, so families can make informed decisions with confidence.” He called for discussions about changes in vaccination policy to be grounded in scientific evidence rather than international comparisons.
Finally O’Leary referenced guidance from pediatric experts: “The American Academy of Pediatrics has published its recommended vaccine schedule for many years, and it remains the trusted standard for keeping children healthy. Following the schedule on time remains the best way to ensure children receive the strongest possible protection.” He affirmed ongoing collaboration within medicine and public health sectors so parents continue receiving credible advice.
