Parents across the country are waking up to a childhood vaccine schedule that looks very different from the one they have known for years. Federal health leaders have sharply reduced the number of shots they actively promote for every child and reorganized the rest into new categories that lean more on individual decisions with doctors.

An overhaul of US childhood immunisation guidelines has dropped the number of diseases children should be vaccinated against from 17 to 11.

In an unprecedented step, Deputy Secretary of Health and Human Services Jim O’Neill, acting as director of the CDC, updated parts of the national immunization schedule, including moving some vaccines ...