The pandemic-ravaged U.S. is set to receive an additional 100 million doses of Moderna's (MRNA 3.06%) coronavirus vaccine, the company announced after market hours on Friday. The government has exercised an option it held with Moderna to purchase that number of doses. This doubles the country's original commitment of 100 million.

Moderna's mRNA-1273 coronavirus vaccine candidate has not yet been approved by the Food and Drug Administration. The company has filed for emergency use authorization (EUA), however. Given the very high efficacy the vaccine has shown in late-stage testing, it's widely expected to receive that green light shortly.

Child getting an injection from a medical professional.

Image source: Getty Images.

When and if that EUA is granted, Moderna said it's prepared to deliver 20 million doses under the initial 100 million commitment by the end of this month. The full balance will come in Q1 of next year. The just-optioned 100 million are to be delivered in the following quarter. 

"Securing another 100 million doses from Moderna by June 2021 further expands our supply of doses across the Operation Warp Speed portfolio of vaccines," Health and Human Services Secretary Alex Azar said of the government-supported drug and vaccine development program.

"This new federal purchase can give Americans even greater confidence we will have enough supply to vaccinate all Americans who want it by the second quarter of 2021," Azar added.

In total, Moderna said it currently has commitments to supply over 390 million doses. Other potential recipients include the countries of the EU, at 80 million; Japan, with 50 million; and Canada, at 40 million. The U.S., meanwhile, still holds an option to obtain 300 million more.