AstraZeneca Plc and Johnson & Johnson together would provide 150 million to 200 million shots in the first quarter, said Moncef Slaoui, chief scientific officer of Operation Warp Speed. This could immunize 110 million to 150 million people, if the doses are evenly split between J&J’s single-dose vaccine and Astra’s two-dose regimen.

That’s on top of vaccines from Pfizer Inc. and Moderna Inc., from whom the U.S. has ordered enough doses for 100 million people combined.

Slaoui detailed the plan in response to criticism that the U.S. left itself exposed by declining to order more doses from New York-based Pfizer, whose vaccine is likely to be authorized for emergency use in the coming days. At the White House’s vaccine summit Tuesday, Slaoui defended the strategy of spreading bets among vaccine makers relying on different technologies. The goal: Ensure the plan wasn’t hindered by any individual clinical failure, manufacturing delay, or poor execution by management, he said.

“Already with this portfolio, I feel confident that we can cover the U.S. population within the first half of 2021,” Slaoui said at the Milken Institute’s Future of Health summit. Later at the White House meeting, Slaoui specified that every person who wanted a vaccine would get access by June.

The U.S. has an agreement for 100 million doses of the Pfizer-BioNTech SE two-dose vaccine regimen, enough for 50 million people. Both shots are needed to provide full immunity. The New York Times and the Washington Post reported Monday that Pfizer had offered an additional 100 million doses to the U.S., which declined.

Scott Gottlieb, the former Food and Drug Administration chief who now sits on Pfizer’s board, said Tuesday on CNBC that the offer remained on the table even after Pfizer released data showing the vaccine was highly effective in a clinical trial. Eventually, other countries took their place in line ahead of the U.S., and now Pfizer’s home nation would have to wait until late summer to get more doses.

Without more Pfizer vaccines for the time being, estimates for when the U.S. can reach herd immunity could be at risk unless the U.S. can get more doses elsewhere, Morgan Stanley analyst Matthew Harrison said in a research note. Harrison had been modeling vaccinations reaching a tipping point by mid-2021.

Earlier Talks

In earlier negotiations with the U.S., Pfizer didn’t guarantee that it would be able to deliver an additional 100 million doses in a specified time frame, according to a White House official who asked not to be identified discussing private information.

The parties remain in talks about the U.S. exercising an option to purchase additional doses, the official said. Pfizer declined to comment on negotiations with the government.

During the White House summit on Tuesday, President Donald Trump raised the specter of invoking the Defense Production Act — which allows the president to require companies to prioritize contracts deemed essential for national security — if the U.S. struggles to obtain the vaccine for its citizens.

However, with more Pfizer doses unavailable for the short run, based on current agreements, the U.S. needs AstraZeneca and J&J to present data to the FDA that shows their vaccines are effective and safe.

J&J Trial

Currently, J&J has recruited more than 35,000 healthy participants to a late-stage clinical trial, for which it hopes to enroll 60,000 people.

Slaoui expects interim data from the trial to read out in early January, though J&J executives have said they expect to report such data toward the end of the month. Warp Speed’s chief scientist added at the White House event that he anticipates J&J’s shot will get a green-light from U.S. regulators in late January or early February.

The U.S. has thus far secured enough doses for 100 million people.

Meanwhile, AstraZeneca and the University of Oxford’s U.S.-based clinical trial has recruited 17,000 participants out of its 40,000-person target, and won’t read out until late-January or early-February, with the potential for an emergency-use authorization coming toward the end of February or early March, according to Slaoui.

Outside the U.S.

Astra and Oxford have a separate trial underway outside the U.S., which has reported more moderate efficacy than the shots from Pfizer and Moderna. The U.S. has reached a deal for 300 million doses of the Astra-Oxford vaccine, which also requires a shot-plus-booster regimen.

Because they use a different technology, AstraZeneca and J&J could scale up manufacturing much more quickly than Pfizer and Moderna, Slaoui said.

A third group of vaccines, one by Novavax Inc. and the other by Sanofi and GlaxoSmithKline Plc, could be authorized in the spring for use in April or May, he said. “Those can also produce hundreds of millions of doses,” Slaoui said.

Moderna Agreement

If all of those candidates somehow fall short, the U.S. still has an an additional option for supply from Moderna, whose vaccine is awaiting authorization from the FDA later this month.

Moderna’s original supply agreement with the U.S. for 100 million doses allows for the government to order 400 million more, according to Moderna spokesman Ray Jordan. A price of $16.50 per dose has already been agreed upon and no new negotiation is required.

Specific opt-in and delivery dates for the option agreements — which can be reached in four 100 million-dose tranches — haven’t been disclosed, said Jordan.

Any additional Moderna shot orders from the U.S. would be fulfilled by plants in New Hampshire and Massachusetts, and the U.S. would be get priority from output from those plants, Jordan said. A separate plant in Switzerland is being used to supply doses for Europe, he said.

Given the timing of the manufacturing scale-up, most of any additional U.S. supply wouldn’t be delivered before the second quarter of 2021.

However, in a note to clients on Tuesday, Morgan Stanley’s Harrison said that the U.S. government’s opt-in period would begin after the Moderna vaccine gains emergency clearance.

“We believe the U.S. government can move quickly,” he wrote. And that if the U.S. does exercise its options, Moderna “could provide the vast majority of doses to the U.S.”

One potential hurdle would be whether Moderna could secure enough raw materials to make all those vaccines, he said. Slaoui said at the Milken Institute event that Operation Warp Speed had anticipated that hurdle, and was currently aiding the various vaccine-makers in acquiring such materials.