• Health and Human Services Secretary Alex Azar said Thursday he'd like "more visibility" into Pfizer's Covid vaccine manufacturing, adding Pfizer has kept the federal government at "arm's length."
• Unlike other drugmakers, Pfizer did not accept federal funding to help develop or manufacture its vaccine.
• But Azar said he would like to see that relationship change. "We're working with Pfizer. We're very optimistic that we'll secure additional quantities in the second quarter, but they're going to need help from us on their manufacturing."

Health and Human Services Secretary Alex Azar said Thursday that he'd like "more visibility" into the manufacturing of Pfizer's coronavirus vaccine, adding the U.S. drugmaker has kept the federal government at "arm's length" throughout the process.

Unlike other drugmakers, Pfizer did not accept federal funding to help develop or manufacture its vaccine. Pfizer has a deal with the U.S. to supply 100 million doses of its vaccine as part of Operation Warp Speed, enough to inoculate 50 million Americans since the vaccine requires two doses three weeks apart. Pfizer is also negotiating with the U.S. for an additional 100 million doses.

"They are part of Operation Warp Speed, but ... it's a different relationship" from the government's deals with Moderna and other pharmaceutical companies that took federal funding, Azar told CNBC's "Squawk Box" during an interview Thursday. "We contract, give [Pfizer] a guaranteed purchase, that allows them to make capital investments, have a predictable purchaser, but we don't have complete visibility into their manufacturing because they have kept that a bit more arm's length."

But Azar said he would like to see the federal government's relationship with Pfizer change.

"We're working with Pfizer. We're very optimistic that we'll secure additional quantities in the second quarter, but they're going to need help from us on their manufacturing," he said. Azar also noted that Pfizer originally said it would produce 100 million doses by the end of the year, but "had to cut that in half to 50 million."

Later Thursday, Pfizer issued a statement, saying that the company "is not having any production issues with our COVID-19 vaccine, and no shipments containing the vaccine are on hold or delayed."

It said that the company has also "continuously shared" information in weekly meetings with HHS and Operation Warp Speed through on "every aspect of our production and distribution capabilities."

"They have visited our facilities, walked the production lines and been updated on our production planning as information has become available," Pfizer said.

Its vaccine was authorized by the Food and Drug Administration for emergency use on Friday. The first doses of Pfizer's vaccine began shipping across the U.S. over the weekend, and Americans began receiving shots on Monday.

Initial doses of Pfizer's vaccine are limited as manufacturing ramps up, with officials predicting it will take months to immunize everyone in the U.S. who wants to be vaccinated. The U.S. shipped 2.9 million doses of the vaccine this week, with an additional 2 million expected next week, Army Gen. Gustave Perna, who oversees logistics for Operation Warp Speed, told reporters on Wednesday. The U.S. hopes to vaccinate 20 million people by the end of the year.

Earlier this month, The Wall Street Journal reported that Pfizer's vaccine rollout target of 50 million doses worldwide by the end of the year was only half of what it originally planned. In a statement, Pfizer said there were several factors that affected the number of doses estimated, including scaling up a vaccine at an "unprecedented" pace.

When asked Thursday why Pfizer isn't able to produce more doses, Azar said the U.S. would offer to help "them get a higher yield if they're willing to take our help."

He said the issue was not a matter of cost, adding, "We're working with them."

"It's very productive discussions," he said. "We'll use the full power of the U.S. government to assist, maximize production as we always have been willing to do. I'm very optimistic we'll get to a good place there."