Federal officials on Wednesday said they anticipate vaccinating as many as 100 million people by March once a coronavirus vaccine is approved and ready to be distributed.
In a call with reporters, HHS Secretary Alex Azar said federal agencies have made preparations to begin allocating a vaccine, or vaccines, immediately after the U.S. Food and Drug Administration grants emergency use authorization for use.
Among the most likely candidates to gain FDA approval first include vaccines developed by makers Pfizer and BioNTech, which won approval for use in Britain on Wednesday, as well as one developed by Moderna.
The FDA's vaccine advisory committee is scheduled to review the Pfizer and BioNTech vaccine on Dec. 10, with Moderna's candidate scheduled for review on Dec. 17.
"We're on track to be able to ship enough vaccine for 20 million Americans before the end of the year," Azar said.
Dr. Moncef Slaoui, who leads the Trump administration's Operation Warp Speed initiative to develop a coronavirus vaccine, projected an additional 30 million would be vaccinated in January and 50 million more in February for a total of 100 million.
Slaoui said distribution could be carried out within 24 hours after the FDA authorizes use of the vaccines.
Since both vaccine candidates likely to get approval first require individuals to take two doses, the federal government will ship a dose at a time for states to distribute.
Slaoui said a final analysis of the Moderna vaccine shows an efficacy rate of more than 94% against moderate and severe disease, which included an efficacy a rate of 87% among patients ages 65 and older.
He said the fact that the Pfizer candidate has already gained approval by a regulatory agency in the UK should provide the public reassurance over the safety and efficacy of a new coronavirus vaccine.
"I hope this will be more evidence for the American population that the data for these vaccines are clear, transparent and demonstrate that they are effective and safe for use within the general population," Slaoui said.
Slaoui also said two more additional COVID-19 vaccine candidates from Johnson & Johnson and AstraZeneca could also gain approval in the next few months, which would increase vaccine supplies.
The Centers for Disease Control and Prevention and the FDA are working developing a surveillance system after the vaccines are distributed to track any adverse health outcomes.
Slaoui said current projections indicate there will be ample supply to vaccinate the country's 3 million residents in long-term care facilities before the end of the year.
But Slaoui failed to answer whether there would be enough supply to vaccinate the 21 million healthcare workers. On Tuesday, a CDC advisory panel voted to recommend frontline heathcare personnel be among the first to receive the coronavirus vaccine.
