Pfizer Inc. will be able to supply the U.S. with 200 million COVID-19 vaccine doses by the end of May, two months sooner than previously expected, according to its top executive.

Chief Executive Officer Albert Bourla said today that the drugmaker and its partner, BioNTech SE, will be able to deliver the doses to the U.S. well before an earlier July 31 deadline due to a change in the vaccine’s label that allows health-care providers to extract an additional dose from each vial.

The six-dose-per-vial count became effective on Monday and applies to supply contracts going forward, according to a Pfizer representative.

In the U.S., Pfizer and BioNTech will deliver 120 million doses in the first quarter, 20 million more than initially promised, Bourla said in an interview with Bloomberg Editor-in-Chief John Micklethwait at the Year Ahead Summit, held virtually this year.

Bourla added that Pfizer and BioNTech would get more doses to the European Union before the end of the second quarter. The companies’ vaccine regimen requires two doses to provide full protection from symptomatic cases of COVID-19.

New York-based Pfizer has supplied governments with 36 combinations of commercially available needles and syringes to be able to extract the last dose from the vials, Bourla said. The drug giant had known its vials contained up to six vaccine doses, he added, noting that at the outset of the year, it had to generate data to garner approvals for its use from government authorities around the world.

The change in Pfizer’s timeline comes amid heightened anxiety over the sluggish pace of the vaccine rollout and concern over a limited supply of doses. Bourla said that the U.S. immunization campaign had been particularly slow in its first few weeks, though he expects the pace of administered doses to improve.

VACCINE ROLLOUT

Vaccinations in the U.S. began on Dec. 14, just days after the Pfizer-BioNTech vaccine was authorized for emergency use. Moderna Inc.’s vaccine, which relies on similar messenger RNA technology, was cleared shortly thereafter. So far, 23.5 million shots have been given, according to Bloomberg’s Vaccine Tracker. In the past week, an average of 1.25 million doses a day were administered.

In all, Pfizer and BioNTech have said they plan to produce 2 billion doses in 2021, a 50% increase from estimates given last year. While the companies plan to ramp up output with the help of additional contract manufacturers, the new target also takes into account a label change that allows doctors to extract six doses instead of five from each vaccine vial.

Bourla said it’s important to administer the second dose of the Pfizer-BioNTech vaccine in the appropriate window of time evaluated and confirmed by clinical trials, which is 19 to 42 days. No data suggest the vaccine will be effective if a second dose is administered after 42 days, Bourla said.

Still, some governments have been willing to accept the trade-off of lower immunity to inoculate more people.

“Every government, of course, has to manage a very complicated situation,” he said.

Bourla said the company is in talks with various governments for additional doses, but declined to comment on whether such discussions were being held with the Biden administration.

BOOSTER FOR VARIANTS

As two new strains of the virus spread globally, Pfizer and BioNTech are also developing booster shots that can protect against various mutations.

“Every time a new variant comes up we should be able to test whether or not [our vaccine] is effective,” Bourla said. “Once we discover something that it is not as effective, we will very, very quickly be able to produce a booster dose that will be a small variation to the current vaccine.”

Bourla’s comments follow news that Moderna is working on a similar booster shot. On Monday, Moderna said its vaccine will protect against two known coronavirus variants, but it plans to start human studies of a booster shot for a strain from South Africa that may cause immunity to wane more quickly.

While Bourla does not anticipate the coronavirus will be eradicated, he said the pharmaceutical industry has the tools necessary to make the virus like the flu.

“That means it would disturb neither our lives, nor socioeconomics. We need to be very vigilant about the strains that exist and very vigilant about vaccinating people,” Bourla said.

People might require a one-shot annual Covid vaccine that is developed each year to combat whatever strain is anticipated to circulate, he said. Pfizer is working on next-generation versions of its vaccine that have easier storage requirements to that end.