The U.S. government paid around $10 billion in the early years of the pandemic to develop and purchase Moderna's COVID-19 vaccine as part of Operation Warp Speed. So far, any American who wants the shot has paid nothing out-of-pocket for it — the federal government has footed the bill.

But once it's time to switch to the next version of the vaccine (expected to be tailored to whatever strain of the virus is circulating later this year), individual patients will have to pay for the shot if their health insurance doesn't cover it. The proposed price: roughly $130 per dose.

Sen. Bernie Sanders, for one, is outraged.

"How is the CEO of this company thanking the taxpayers of this country who are responsible for making him and his colleagues incredibly rich?" Sanders asked rhetorically on the Senate floor recently. "He is thanking them by proposing to quadruple the price."

Sanders chairs the Senate Committee on Health, Education, Labor and Pensions, which has called Moderna CEO Stéphane Bancel in for questioning about the company's pricing plan on March 22.

The same day Bancel's appearance before the committee was announced, Moderna said it would provide the vaccine to uninsured or underinsured patients at no cost. This patient assistance program is set to begin in May.

Moderna's move is politically savvy, says Larry Levitt, executive vice president for health policy at the Kaiser Family Foundation.

"This gives Bancel a talking point when he appears before Bernie Sanders," Levitt says. "I think it blunts the criticism, but I think there will still be plenty of criticism."

Drug companies still keep prices high

Patient assistance programs have long been part of the drug industry playbook. They allow companies to maintain high prices while diffusing some of the criticism. The hitch is that patients have to jump through hoops to get these free or discounted pharmaceutical products.

Claire Hannan, executive director of the association of immunization managers, says paperwork and red tape can be a real problem.

"I think people are willing to push through that if they need to get a drug," she says. Patients who are taking expensive drugs for cancer treatment or chronic conditions may be facing hundreds or thousands of dollars in drug costs over time, so it's worth it to them to go through even a complicated application process.

If someone's not sick, the urgency just isn't the same, Hannan notes. "With the vaccine, you really have to make that accessible and convenient for people to get it."

"This is already a very hard to reach group"

If it's not easy to apply for Moderna's free vaccines, people could decide not to bother.

"We are having trouble getting people vaccinated and boosted" Levitt says, "and people who are uninsured are the least likely to be vaccinated. So this is already a very hard-to-reach group. And it's going to get harder — even with this patient assistance program."

NPR asked CVS and Walgreens whether they had plans to help patients navigate the Moderna patient assistance program — since a lot of people get vaccinated at pharmacies. CVS said it didn't have anything to share right now. Walgreens did not respond.

Hannan says for local clinics and health departments to be able to participate, there are two obstacles: buying the vaccine so it's there when patients ask for it and having staff to handle the paperwork.

"Purchasing that initial stock can be a challenge if they don't have vaccine," Hannan says. "So hopefully Moderna is willing to provide that."

It's not a surprise that the vaccine's price is about to go up.

"Basically it was like we had Medicare for All when it came to vaccines and now it's back to the way our health system normally works," says Levitt.

It's a little late to drive a hard bargain

Drug industry observers say the time for the government to drive a hard bargain on future pricing would have been in 2020 when Operation Warp Speed was negotiating vaccine development and purchase contracts with drugmakers including Moderna, Pfizer, Johnson and Johnson and others.

NPR reported on these contracts at the time, including a story about how Pfizer was behind on its initial delivery deadlines, but there was nothing the government could do about it.

Jamie Love, of Knowledge Ecology International, a nonprofit advocacy group focused on social justice issues, says the government didn't do a great job.

"It was all short term thinking," Love says. "It came out of a period when the government was also kind of reluctant to even say anything about prices."

And that's set the stage for the vaccine pricing we're seeing now, he says.

Pfizer executives told investors last fall that they planned similar commercial prices for their COVID-19 vaccine — in the range of $110 to $130 per dose. Pfizer tells NPR it also plans a "patient assistance" program to help defray that cost. The company opted out of the same level of federal support and involvement that Moderna received during the early days of vaccine development, but it still received some giant government contracts. Johnson & Johnson, the third Operation Warp Speed drugmaker whose vaccine was made available in the U.S., has not yet announced a commercial price for its vaccine.