US healthcare workers and others recommended for the nation's first COVID-19 inoculations could start getting shots within a day or two of regulatory consent next month, a top official of the government's vaccine development effort says.
About 70 per cent of the US population of 330 million would need to be inoculated to achieve "herd" immunity from the virus, a goal the country could achieve by May, according to Dr Moncef Slaoui, chief scientific adviser for "Operation Warp Speed".
Slaoui said the US Food and Drug Administration would likely grant approval in mid-December for distribution of the vaccine produced by Pfizer and German partner BioNTech, launching the largest inoculation campaign in US history.
The FDA's outside advisers are slated to meet on December 10 to review Pfizer's emergency-use application for its vaccine, which the company said was found to be 95 per cent effective.
A second company, Moderna, is expected to seek separate approval later in December for its vaccine.
For the Pfizer vaccine, Slaoui told CNN on Sunday that "maybe on day two after approval on the 11th or 12th of December, hopefully the first people will be immunised across the United States".
Once emergency-use approval was granted, Slaoui said, the US Centers for Disease Control and Prevention and an advisory panel would recommend who should receive the vaccine first, likely to be frontline medical personnel and high-risk groups such as the elderly.
President-elect Joe Biden's transition team has voiced concern that President Donald Trump's refusal to share vaccine data could cause delays after the next administration takes office on January 20.
Slaoui said he hoped for a smooth hand-off and did not expect the vaccination effort to be derailed.
Coronavirus infections continue to rage out of control across the country and experts worry the surge will only worsen as millions of Americans prepare to travel for Thanksgiving celebrations despite warnings they stay home to avoid spreading the disease.
The United States surpassed 12 million COVID-19 cases on Saturday, as the nation's death toll climbed to more than 255,000. Coronavirus hospitalisations have increased nearly 50 per cent in the past two weeks.
The epicentre of the US pandemic has also shifted in recent weeks, with the midwest and Rockies leading the nation in terms of rapidly escalating infections.