President Joe Biden has toured a state-of-the art coronavirus vaccine plant, intent on showcasing progress in vaccinations even as extreme winter weather across the US delayed shipment of about six million doses and closed of inoculation sites in many communities.
The storms handed Biden's vaccination campaign its first major setback and while acknowledging the weather was "slowing up the distribution", Biden said at the Pfizer plant in Michigan that he believed "we'll be approaching normalcy by the end of this year".
His on Friday speech recited his administration's accomplishments against the pandemic, a pitch for his $US1.9 trillion ($A2.4 trillion) COVID relief bill and criticism of his predecessor Donald Trump.
The disruptions caused by frigid temperatures, snow and ice have left the White House and states scrambling to make up lost ground as three days worth of vaccine shipments were delayed. Even the president's trip to see Pfizer's largest plant was pushed back a day due to a storm affecting the nation's capital.
Biden has set a goal of administering 100 million shots in his administration's first 100 days and he said Friday that was still on track and only a beginning.
He said by the end of July his administration could deliver 600 million doses for Americans. Still, Biden cautioned that timetable could change, citing the current weather delays and concerns about new strains of the virus.
"God willing, this Christmas will be different than last but I can't make that commitment to you," he said in a warehouse filled with hundreds of ultra-cold freezers each holding 360,000 vaccine doses.
The Pfizer plant Biden toured, near Kalamazoo, produces one of the two federally approved COVID-19 shots. Weather-related delays have affected distribution of the Pfizer and Moderna vaccines.
Introducing Biden before the speech, Pfizer chief executive Albert Bourla called his administration "a great ally" and cited a range of actions that had helped the company as it looked for ways to increase production.
In a media release, the company said it had been shipping five million doses a week in the US on average and expected to more than double that by the end of March.