US president Joe Biden has said there will be enough vaccines to inoculate every American adult by the end of July, as his administration purchased 200 million extra shots.
The US exercised options built into its existing contracts with Pfizer-BioNTech and Moderna, ordering 100 million doses of each of the two vaccines authorised for use in the United States.
It brings the total number of vaccines ordered by the United States to 600 million – enough to vaccinate most of America’s population of 330 million.
Mr Biden announced the new orders as he toured the National Institutes of Health in Washington. But he also warned that logistical challenges mean that many Americans will still not be vaccinated by the end of the summer.
News of the fresh supply came as leading immunologist Anthony Fauci said this week that most Americans, outside the priority groups, could begin accessing vaccines by April.
“By the time we get to April, that will be what I would call . . . ‘open season’, namely, virtually everybody and anybody in any category could start to get vaccinated,” he said.
The rollout of vaccines in the US has picked up pace in recent weeks. Mr Biden sanctioned a 30 per cent increase in vaccine allocations to states, though it falls to individual states to manage their vaccination programmes, in line with guidance from the Centres for Disease Control and Prevention (CDC).
Approximately 1.5 million vaccines per day are now being administered, though some areas of the country are experiencing huge demands on their supply, leading to cancelled appointments and long queues.
More than 475,000 Americans have died from Covid-19, while more than 27 million cases have been confirmed.
Speaking as he hosted a meeting of governors and mayors in the Oval Office on his economic recovery plan on Friday, Mr Biden said his priority was getting the vaccines directly to governors.
But the president was also accused of breaking a pre-election pledge that the majority of schools would reopen in his first 100 days in office. White House press secretary Jen Psaki said this week that the goal could involve most students having just one day of in-person learning a week.
In a roadmap published on Friday, the CDC recommended that schools return to a combination of in-person and remote learning, but also stating that teacher vaccination was not a prerequisite for reopening.
Many public schools around the country have remained closed throughout the pandemic, with state and local officials battling with teacher unions objecting to their members returning to the classroom.
Meanwhile, New York governor Andrew Cuomo, who attended Friday's meeting with Mr Biden in the White House, was facing allegations that the state covered up data on nursing home deaths. More than 10,000 people died in nursing homes in New York state since the outbreak of the pandemic, but the state has been reluctant to release information about the precise numbers.
Asked about the decision by Montana’s governor to lift the state’s mask mandate, White House press secretary Jen Psaki said that Mr Biden encourages people to “follow federal guidelines”.
It follows recommendations by the CDC that two masks, or tight-fitting masks, can significantly reduce the transmission of Covid-19 in the general population.