And, of course, it worked—incredibly well. For Pfizer’s role in developing one of the globe’s most effective weapons against COVID-19, Bourla now finds himself getting impromptu standing ovations at restaurants; his employees, recognized by grateful members of the public, sometimes have their groceries paid for. It’s likely that a few weeks from now, Pfizer will be the first vaccine authorized for children between the ages of 5 and 12 in the U.S. For maybe the first time ever, the world has warm feelings for Pfizer, which has also in short order become a household name. It’s no wonder employee engagement is through the roof; 96% of its 60,000 employees said in the company’s most recent annual survey they are very proud to work at Pfizer.

Meanwhile, the company’s revenues and stock price have been at all-time highs; Pfizer, which manufactured 200 million vaccines per year before the pandemic, will make more than 3 billion of them in 2021, for more than $30 billion in sales. “In all metrics, Pfizer is right now at the peak of its entire history of 173 years,” Bourla told Fortune’s Maria Aspan, at a virtual Fortune Connect event on Wed. Oct. 20. That’s all great, but the question that has been nagging at Bourla is: How do we sustain this?

“When you are at the top, you can’t stay there,” Bourla told Aspan. “Either you go higher, or you go down. That’s what’s in my mind right now.”

Bourla’s plan for even greater heights starts with not taking that position for granted. “I think we need to earn it everyday, with everything we do,” he said, while acknowledging the company’s pandemic achievement has created a precious resource that can’t be squandered: an energized corporate culture.

“We have the entire organization living day in and day out our efforts to develop something that no one thought possible. And we’ve proven to all, including ourselves, that nothing is impossible,” said Bourla. “That’s the biggest asset Pfizer has right now,” he added, noting that all divisions of the company want to replicate the success of the COVID vaccine effort.

The importance of culture

During the pandemic, Bourla also took care to ensure employees, whether they worked on the vaccine or not, shared in that accomplishment and felt a part of the company culture. The company increased its internal communications, relaying frequent updates on the progress of the COVID work: “People were really focusing and following the efforts to develop our vaccine, as now they are on the development…of our oral pill treatment that could treat COVID. It was an extremely big part of the pride employees feel.”

Pfizer kept everyone on payroll during the pandemic, whether they were able to do their jobs or not—a decision that came easily for Bourla and his leadership team: “There are moments of how you treat your people that stay with them forever. It was very clear to us that when this story is over we want to find ourselves on the right part of history.”

The CEO is now focused on harnessing that motivated and unified organization to develop more life-changing, breakthrough medications. Bourla, who compares aspects of his job to running “the world’s largest casino,” has more than $10 billion dollars in R&D budget to invest in that cause every year, and he considers risk management—assessing and weighing the likelihood of success of certain projects, against available capital—a key part of his job. (With betting on a COVID vaccine, he noted the calculation was different, and much less rigorous: “This wasn’t about the future of the company, or of me, but the future of the world.”) Pfizer is now doubling down on additional mRNA vaccines and therapeutics, which Bourla expects will yield rewards as early as next year. He hopes to see a successful mRNA cancer vaccine—the technology can be used to attack tumors—in three years.

Love at first sight

Bourla does not see Pfizer getting there on its own, but though strong partnerships—like the one it shares with mRNA collaborator BioNTech (“It was love at first sight,” he said)—which he believes are vital for a thriving pharma industry. As he sees it, in today’s landscape, his company is only as good as it is perceived by potential partners.

“Science will not happen, like 30 years ago, in the labs of some Ivy League university or very big pharma. That’s where things were happening; there were 10 players that could do it. Now there are 10,000 players because there are many different startups and biotechs. The only way you can be successful with this is if you are a very trusted part of a big biotech ecosystem,” he noted. “This is how I want to position Pfizer.”

Beyond making medicines

Bourla understands his job leading Pfizer today goes beyond making medicines and managing his workforce. “We are a corporation, and in the modern world, businesses started to have an opinion about social issues, and there is a role we have to play, and there is an expectation,” he said. Bourla, who has spoken publicly and felt the positive impact of sharing his family’s history and his parents’ experience as Holocaust survivors, added: “I think we need to be very vocal in terms of what are the values that we represent as a major corporation and speak about them.”