We epidemiologists are always mindful of what’s known as herd immunity (often called community protection) threshold — calculated as the proportion of individuals who need to be immune to prevent outbreaks. In mid-adolescence, when children have had multiple years to catch up on vaccines they didn’t get earlier, immunization levels are still dangerously close to dropping under the herd immunity threshold for measles. Similar findings have been subsequently reported by other researchers, highlighting the need for interventions to improve measles vaccination rates.

While the risk of a national measles resurgence or a large multi-state outbreak is real, it is not guaranteed. But if we want to prevent it, we need a coherent response to vaccine hesitancy. Fortunately, an evidence-based blueprint exists in the form of recommendations published in 2015 by the National Vaccine Advisory Committee, an independent committee charged with the advising the Department of Health and Human Services. These recommendations focus on evidence-based strategies for increasing confidence in vaccines. Unfortunately, these recommendations have not been fully implemented.