Exemptions from immunization requirements among kindergartners hit their highest level on record this past school year.

Dr. Noel Brewer, a former ACIP member removed by Kennedy and a professor in the department of health behavior at the University of North Carolina Gillings School of Global Public Health, told ABC News that since the upheaval of the ACIP, vaccination has changed in the U.S. in a "fundamental" way and that the committee has "lost credibility."

All 17 experts from the Advisory Committee for Immunization Practices who were replaced last month by Robert F. Kennedy Jr. called the health secretary's new picks "inexperienced and biased."