Mia Fontes, 15 shows the stickers she received Thursday after being inoculated with the second dose of the Pfizer COVID-19 vaccine at the American Museum of Natural History in New York. Credit: Mary Altaffer / AP

Pfizer Inc. and BioNTech SE will supply the U.S. with another 200 million doses of their COVID-19 shot, setting up a stream of vaccine deliveries through next April in a push to protect kids and potentially provide boosters.

The White House is setting its sights on immunizing children under the age of 12, who aren’t yet eligible, and potentially deploying booster doses if new data show their necessity, according to a Biden administration official familiar with the contract.

Of the new doses, 65 million will be tailored for the pediatric population, should the vaccine be cleared for kids younger than 12, according to the official, who spoke under the condition of anonymity as the contract isn’t public. Some of those shots would be immediately available upon authorization.

White House press secretary Jen Psaki said Friday that the administration is preparing for shots for kids under 12 and possible booster shots. Pfizer declined to comment on contract details regarding the pediatric vaccines.

The U.S. also has the option to acquire an updated version of the vaccine to tackle potential variants if it’s available and authorized, Pfizer and BioNTech said Friday in a statement announcing the supply agreement.

Pfizer’s shares gained 0.4 percent at 12:34 p.m. Friday in New York, while BioNTech’s American depository receipts fell 0.3 percent. Pfizer declined to comment on contract details regarding the pediatric vaccines.

The new U.S. deal coincides with a back-to-school push to get children immunized. The Pfizer-BioNTech vaccine was cleared for those 12 and older in May, and studies in younger children are underway. The companies could learn by the fall whether the vaccine provides immunity in those as young as 6 months old.

U.S. health officials have said the government could be ready to vaccinate children of any age within the first quarter of 2022. In an effort to shift public perspective, they’ve warned of the risks the coronavirus and its variants pose to kids. Anthony Fauci, the top U.S. infectious-disease doctor, has turned to TikTok and other social-media platforms to underscore the consequences of youth remaining unvaccinated.

Children under 12 would get smaller dosages of the two-shot Pfizer-BioNTech regimen. In the pediatric trial, those ages 5 to 11 are receiving one-third of the dose given to adults, and children under 5 are getting one-tenth.

To launch new U.S. campaigns deploying shots to children or booster doses to already-immunized Americans, preparations must begin now. All together, the deal brings the total Pfizer-BioNTech doses to be supplied to the U.S. to 500 million.

“These additional doses will help the U.S. government ensure broad vaccine access into next year,” Pfizer Chief Executive Officer Albert Bourla said. Some 110 million of the additional shots will be shipped this year, and the rest will be delivered no later than April 30, the companies said.

While the U.S. government has secured enough to fully vaccinate all eligible Americans, it’s also evaluating providing extra protection to the vulnerable, such as the elderly and those with weakened immune systems.

Concerns about whether additional booster shots will be needed to top up immunity for people who’ve already had both doses of the vaccine are rising as the delta variant spreads around the world. Pfizer said earlier this month that it plans to request emergency authorization for a third booster dose in August.

Pfizer’s announcement that it would seek clearance for booster doses prompted an unusual rebuke from U.S. health officials, who said it was too early to know if they would be needed and that the agency wouldn’t rely only on drugmakers’ data for a decision. Bourla called Fauci, who also serves as Biden’s top Covid medical adviser, to apologize.

The Food and Drug Administration and Centers for Disease Control and Prevention are closely monitoring vaccine protection’s durability and efficacy against variants. As the virus continues to spread in unvaccinated areas of the U.S., many experts are concerned more virulent strains could emerge.

The Biden administration official said Friday that it’s possible the U.S. would deploy booster shots if studies show they are necessary.

Some people may need booster doses sooner than others. On Thursday, advisers to the CDC demonstrated early support for providing boosters to the immunocompromised, for whom vaccine protection is likely to wane more quickly. The Advisory Committee on Immunization Practices did not make a formal recommendation.

As the U.S. reaches yet another deal for doses, nations around the world are still left without much supply for their most vulnerable.

The global coronavirus immunization campaign has been plagued by unequal access to vaccines. Only 1 percent of people in low-income countries have received at least one vaccine dose, according to humanitarian organization Doctors Without Borders.

“As one of the world’s major purchasers of COVID-19 vaccines, the U.S. government’s next steps on boosters and redistribution of its vaccines will be immensely consequential to whether we can finally end this pandemic,” said Carrie Teicher, director of programs at Doctors Without Borders’ U.S. arm.

The U.S. government and the Pfizer-BioNTech partnership have said that deploying doses to countries in need remains a priority. They reached a deal in June to supply the U.S. with 500 million doses for donation to low-income countries. Doses will begin shipping in August.

The vaccine partners are also expanding their supply chain around the world, bringing on new facilities in Europe and South Africa, while exploring new opportunities in Latin America.

New York-based Pfizer and Germany’s BioNTech have shipped more than 1 billion doses of the regimen to more than 100 countries or territories. They aim to deliver a total of 3 billion doses in 2021, and 4 billion doses in 2022.

Story by Riley Griffin.