Kennedy's acknowledgement of the value of the measles vaccine comes as the outbreak that began in Texas continues to grow. So far, nearly 150 cases and one death—the first U.S. fatality from the disease in more than 10 years—have been confirmed. It's the largest measles outbreak in the U.S. in decades.

Forensic pathologist Dr. Michael Baden shared his theory on the "unusual" circumstances that may have led to the deaths of Gene Hackman, his wife Betsy Arakawa and their dog.

Health Secretary Robert F. Kennedy Jr. publicly backed the measles vaccine Sunday amid an outbreak of the disease in Texas that has already killed one child.