Health Secretary Robert F. Kennedy Jr. is spearheading a massive, behind-the-scenes research initiative into vaccine safety despite publicly toning down his criticism at White House request. The sprawling effort across multiple health agencies could cost an estimated $40-50 million just through the CDC, diverting significant resources from other public health priorities.

Working with biostatistician Martin Kulldorff, Kennedy's team is examining whether vaccines contribute to chronic diseases, autism, and other conditions. The initiative includes controversial studies comparing vaccinated and unvaccinated children, despite methodological concerns about such research from the scientific community.

The inquiry raises alarms among public health experts who accuse Kennedy of cherry-picking data to support preconceived conclusions. Critics worry the expensive research will erode public confidence in vaccines, which the WHO credits with saving 154 million lives over five decades, while potentially delaying answers to more pressing health questions.