Vas Narasimhan was drawn to work in public health. He pursued degrees in medicine, worked to combat disease in India and Africa and studied with Paul Farmer, the renowned physician.

But after a brief stint at the World Health Organization, he became disillusioned with public-sector bureaucracy. “I found there to be a dearth of real leaders,” Mr. Narasimhan said. “There wasn’t a mind-set of: How do you create great leaders and how do you lead large organizations?”

Instead, Mr. Narasimhan went into the private sector. He worked at McKinsey for a short time, then joined Novartis, the giant drugmaker, in 2005. He has held various roles since then: head of U.S. vaccines, head of the company’s Sandoz biopharmaceuticals development unit and head of global drug development and chief medical officer. When he became chief executive last year, he was just 41.

Mr. Narasimhan is on a relentless quest for self-improvement, working with an executive coach, using meditation apps, exercising daily and practicing intermittent fasting. At the same time, he is hoping to improve the damaged reputation of the pharmaceuticals business.

This interview, which was condensed and edited for clarity, was conducted in New York.

What was your childhood like?

My grandparents were from villages in India. Both of my grandmothers only had first- or second-grade educations. Both married as young teenagers. My grandfather was the first person in his family to leave the village and go to college. Then my parents, similarly, were the first in our family to come to the United States.

My father is a physical chemist who moved into the business world and was the head of research and development for a chemicals company. My mother is a nuclear engineer. It was really kind of an immigrant childhood. I learned to speak Tamil before I learned to speak English. My parents started a temple in Pittsburgh, which is still there to this day. And despite living in the United States, I really spent my time growing up trying to recreate kind of the Indian atmosphere.

What did you study in school?

I went to the University of Chicago and did pre-med. Then for my junior year of college I went to Gambia where I worked with the Red Cross in malaria control. That was my first exposure to public health.

I came back and decided to study the great books program. So I read Aristotle’s “Ethics,” Plato’s “The Republic.” I took a whole course just reading one book, Tolstoy’s “War and Peace.” I was sort of a closet philosopher, I guess. Then I decided to go to medical school, and I got into Harvard.

Did you have any sense of what you wanted to do in the field of health?

I wanted to be in public health. I went to Calcutta, India, after my first year of medical school, and then I went to Africa a few other times. And I really began to think about how to impact public health on a large scale. Somewhere in the journey, I decided that I did not want to impact health by working with individual patients. I wanted to have a bigger impact on populations. The question was: Do you do that through public health? Do you do that through private business?

So you decided to join McKinsey. What happened?

I promptly got put on M&A projects. That’s what happens. And I had an aptitude for translating medicine into valuation models. It was a skill set that I still use today. Frankly, the fact that I can build my own model is something useful in a job like this. I don’t want to criticize McKinsey. It’s often portrayed that I was at McKinsey for an extended period of time. I was there for about 18 months.

You’ve had a variety of roles at Novartis. Which were the most formative?

The real trial by fire for me was leading our response to the H1N1 pandemic in 2009. Novartis had become the largest supplier of H1N1 vaccines to the U.S. government. We were behind, as were all companies, because we were trying to develop these vaccines in, like, six months, something that usually takes about six years. We were far enough behind that I was on calls with Kathleen Sebelius, the health secretary, and the White House, under huge amounts of pressure to figure out how to make this all happen.

It became clear that the only way to get the organization to deliver 150 million doses of vaccines was to inspire people. It was such an audacious thing to try to get all of this done. And in the end we did pretty well. We were only a couple of months later that we needed to be to get the full supply in.