As scientists and pharmaceutical companies work at breakneck speed to develop a vaccine for coronavirus, public health officials and senior US lawmakers are sounding alarms about the Trump administration's lack of planning for its nationwide distribution.
The federal government traditionally plays a principal role in funding and overseeing the manufacturing and distribution of new vaccines, which often draw on scarce ingredients and need to be made, stored and transported carefully.
There won't be enough vaccine for all 330 million Americans right away, so the government also has a role in deciding who gets it first, and in educating a vaccine-wary public about its potential life-saving merits.
Right now, it is unclear who in Washington is in charge of oversight, much less any critical details, some state health officials and members of Congress told Reuters.
A senior Trump administration official last week told Reuters that Operation Warp Speed, a White House taskforce first announced in May, was "committed to implementing the [vaccine] plan and distributing medical counter-measures as fast as possible".
However, Dr Robert Redfield, director of the Centres for Disease Control and Prevention (CDC), told a Senate hearing on July 2 that his agency would spearhead the campaign to develop and distribute a vaccine for the new coronavirus. "This is really the prime responsibility of CDC," he added.
Republican Senator Roy Blunt, who chairs a panel overseeing health programme funding, is one of several lawmakers pushing for the CDC, which was founded in 1946 to counter malaria, to lead the effort.
"They are the only federal agency with a proven track record of vaccine distribution and long-standing agreements with health departments across the country," Blunt said.
The US leads the world in Covid-related fatalities with more than 150,000 in five months. After underestimating the virus' threat, President Trump and his advisers are embroiled in internal battles over how to handle the crisis just three months before his re-election bid. A July 15-21 Reuters/Ipsos poll showed that only 38pc of the public supports Mr Trump's handling of the pandemic.
Health officials and lawmakers say they worry that without thorough planning and co-ordination, the vaccine distribution could be saddled with the same sort of disruptions that led to chronic shortages of coronavirus diagnostic tests.
Senator Patty Murray, the senior Democrat on the health program funding committee, said Washington should be educating people now about vaccination plans to build public confidence and avoid confusion.