The US aims to acquire an additional 200 million doses of COVID-19 vaccines, President Joe Biden said on Tuesday, enough to inoculate most Americans by summertime.
Biden's administration will purchase 100 million doses each of the vaccines made by Pfizer Inc and BioNTech, and Moderna Inc, increasing the overall total doses to 600 million, with delivery expected by summer.
The previous purchase target was 400 million doses.
Each vaccine requires two doses per person to be fully effective, suggesting the new purchases would build up enough of a stockpile to inoculate most of the country's 331 million people. The vaccines are not approved for use by most children.
"This is a wartime effort," Biden said in the White House State Dining Room.
Pfizer is confident it can deliver the extra doses in the time frame specified by Biden, spokeswoman Sharon Castillo said.
Moderna declined to comment.
The new purchase target, along with promises to get more vaccine to local authorities, raises the bar for a Democratic president who took office last week with vows to repair what he said was a disastrous emergency response by his Republican predecessor, Donald Trump.
Biden said he would hike the amount of the vaccine going to local governments to 10 million doses per week for the next three weeks, up from 8.6 million currently. The news was welcomed by governors, who said they needed even more doses.
"We appreciate the administration stating that it will provide states with slightly higher allocations for the next few weeks, but we are going to need much more supply," Republican Maryland Governor Larry Hogan said in a statement after being briefed on a call by Jeff Zients, the administration's COVID-19 response coordinator.
"I urge President Biden to take every imaginable step within his power to ramp up production without delay."
The pandemic, which has killed over 420,000 Americans, is currently infecting more than 173,000 people daily and has left millions out of work.
"Cases will continue to mount," Biden warned. "We didn't get in this mess overnight. It's going to take months for us to turn things around. Let me be equally clear: We're going to get through this. We will defeat this pandemic."