Before becoming a California state senator, Richard Pan (MD ’91), a pediatrician, was on the faculty at the UC Davis Children’s Hospital and helped establish organizations to build healthier communities. (One of those organizations resulted in 65,000 Sacramento-area children gaining access to health, vision, and dental care.) Two years ago, TIME called Pan, 51, a hero after he authored Senate Bill 277, which eliminated the personal belief exemption that many parents had used to prevent getting their children vaccinated. This spring, Pan gives the commencement address to the University of Pittsburgh School of Medicine’s Class of 2017.

Why was your vaccine legislation important? 

[People were] worried that [their kids were] going to catch a deadly disease at school because some other parents decided not to vaccinate their children. Their schools were unsafe. And so, SB277 is about [restoring] community immunity to neighborhoods in California.

What problems will Pitt med graduates face? 

In the late 1800s, early 1900s, . . . there were very few truly effective drugs, a handful. So a lot of physicians became leaders in the community—creating hospitals and so forth—because they realized that that’s where they could make the most difference; because what they had in their black bags back then was pretty limited. After World War II, we made tremendous strides in developing the kind of science and technology to be able to help individual patients. We developed new medications, new techniques, new procedures, devices. . . .

But we also realized that the problems facing [many of] our patients, like obesity, addiction, behavioral issues, are not ones we can solve [by] going to the pharmacy or the O.R. We need to understand the social determinants of health. [Doctors] were more integrated in [community wellness 100 years ago]. We sort of became dis-integrated [as we acquired] more tools, . . . and public health became more of a government function. Somewhere, we’ve got to bring those two [roles] back together again. And I think that’s the challenge. Even when we think about health care costs—we spend 70, 80 percent of a health care dollar on managing chronic diseases. That’s where all the money is going.