Moderna Inc.’s chief executive officer said the company doesn’t plan to invest in new late-stage vaccine trials because of growing opposition to immunizations from US officials.

“You cannot make a return on investment if you don’t have access to the US market,” Stéphane Bancel said in an interview with Bloomberg TV from the World Economic Forum in Davos, Switzerland. Regulatory delays and lack of support from US health officials are making the potential market size “much smaller,” he said.

Bancel’s comments are some of his strongest yet about the difficulties that vaccine makers face in the Trump administration. He joins a chorus of other pharmaceutical executives who have started to vent their frustrations with the government’s assault on immunizations.

“It’s sad for us to see that vaccines that have been proven for decades helping people around the world are not recommended anymore,” Bancel said.

Under the leadership of Health Secretary Robert F. Kennedy Jr., a vaccine critic, US officials have narrowed the population of people who are eligible for Covid vaccines, created confusion over how to get them and raised questions over their safety. That’s made things even harder for Moderna, which was already struggling from a post-pandemic decline in its Covid business.

Moderna is trying to transition from a company largely focused on Covid shots to one that makes personalized cancer treatments. The company has said it’s seeking outside funding to run late-stage trials of its other vaccines that protect against viruses that can lay dormant and undetected in the body after an infection, like Epstein-Barr virus and herpes simplex virus.

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