Image by Pixabay/Victor Tangermann

The United States government has announced it will pay pharmaceutical company Pfizer almost $2 billion for an additional 100 million doses of its COVID-19 vaccine, Reuters reports.

Seventy million doses will be supplied by June 30 and the rest will arrive by July 31, according to Pfizer. The government so far has ordered a total of 200 million doses.

It's a tight race. The U.S. is still experiencing record numbers of new confirmed cases and several thousand deaths attributable to the deadly virus every day.

Vaccination efforts began earlier this month. By Monday, US healthcare workers had already administered more than half a million COVID-19 vaccine doses, according to the US Centers for Disease Control and Prevention (CDC). The doses were mostly distributed to healthcare personnel and long-term care facility residents.

As of today, more than 600,000 Americans have been injected.

"This new federal purchase can give Americans even more confidence that we will have enough supply to vaccinate every American who wants it by June 2021," US Department of Health and Human Services (HHS) Secretary Alex Azar said in a statement. "Securing more doses from Pfizer and BioNTech for delivery in the second quarter of 2021 further expands our supply of doses across the Operation Warp Speed portfolio."

The news also comes days after the US Food and Drug Administration approved a second COVID-19 vaccine for emergency use from pharmaceutical Moderna. So far, the US government's Warp Speed program has secured 100 million doses of the Moderna vaccine with the option to buy an additional 400 million. 20 million doses will be delivered by the end of 2020.