Temple University is experiencing a mumps outbreak. As of last week, 11 people tested positive for the disease while 36 more showed symptoms. Temple has taken precautions, including requiring new students to get vaccinated. But questions remain: Why did this outbreak happen at Temple? And why would there be an outbreak of an illness for which we’ve had a vaccine since the 1960s? Dr. Paul Offit, director of the Vaccine Education Center at the Children’s Hospital of Philadelphia, joins us on this episode of The Why.