Millions of Covid-19 vaccines sit unused in US hospitals and elsewhere a week into the huge inoculation campaign, putting the government's target for 20 million vaccinations this month in doubt.
As of Wednesday morning, only a million Pfizer-BioNTech Covid-19 vaccines had been administered, about a third of the first shipment sent last week.
More than 9.5 million vaccine doses, including Moderna's, have now been sent to states, according to the US Centres for Disease Control and Prevention.
While hospitals started giving out Moderna's vaccine, the CDC has not yet reported that data and there may be a lag in reporting the administration of the Pfizer-BioNTech and Moderna vaccines.
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The slow pace has barely picked up from the first week when 614,000 inoculations were given although nearly 2.9 million were shipped.
Hospitals said the first Covid-19 vaccinations started slowly last Monday as they prepared the frozen vaccines for use, finding employees to run the vaccination clinics, and ensuring proper social distancing before and after vaccination. Some said they did only about 100 patients the first day.
They were contending with a Covid-19 surge, as cases around the United States surpassed 18 million with 323,000 deaths.
The Trump administration promised to vaccinate 20 million by the end of the year but provided little funding to achieve the goal.
That is nine days to administer nearly 19 million vaccines, more than two million people a day, including Christmas Day.
Almost 5.9 million doses of Moderna's vaccine should go out this week and an additional two million doses from Pfizer and partner BioNTech.
"The commitment that we can make is to make vaccine doses available," US Operation Warp Speed chief adviser Dr Moncef Slaoui said on Wednesday. He said the rate of people getting vaccinated is "slower than we thought it would be".
Two more vaccines may be approved in February – from Johnson & Johnson Inc and AstraZeneca.
The government's goal is 100 million Pfizer-BioNTech and Moderna vaccines aministered by March 1.
Operation Warp Speed's Gen Gustave Perna, who is leading the vaccine distribution effort, on Monday said that the CDC data reflects a reporting lag and that the number of vaccinations will catch up as time goes on.
The CDC said its data may also reflect a lag between vaccine dosing and state reporting. Most nursing home vaccinations began in mass only this week, and the CDC data does not specify how many doses from the first shipment were being held by states for that group.
Margaret Mary Health, a 25-bed rural hospital in Indiana, built a drive-thru vaccination clinic at a local fire station and one at a local recreation centre to vaccinate healthcare workers in the surrounding counties, according to chief executive Tim Putnam.
Mr Putnam, who has done traffic control at the clinic's drive-thru, said they have used about 400 of 1,100 doses received.
"We're asking for volunteers from our staff, volunteers from the local community college, to step in and build this process from the ground up," he said.
Some of the largest US hospitals inoculated more than 1,000 people per day, having done dry runs for the vaccine delivery and launch.
Vermont, Delaware and Idaho were among states that confirmed their states had given only thousands of doses – a fraction of those available to them – during the first week.
Jason Schwartz, assistant professor of health policy at Yale School of Public Health, described the initial tally as discouraging and said "the challenges of getting vaccines out as quickly as we're able to manufacture them will only grow".
Johnson & Johnson's one-shot vaccine could speed deployment because it requires a conventional refrigerator and has no specialised procedures to thaw out and administer, said Claire Hannan, executive director of the Association for Immunisation Managers trade group. AstraZeneca's two-dose vaccine also can be stored in a refrigerator.
"When it's refrigerator-stable and a one-dose regimen, it can't get any easier than that," Ms Hannan said.
Dr Saul Weingart, the chief medical officer of Tufts Medical Centre in Boston, said the hospital had given about 750 doses of the 3,000 available as of Friday.
It started with 100 inoculations a day and worked up to about 450, he said.
He said modelling by experts at the hospital suggested giving Pfizer's Covid-19 vaccine would take 10 minutes, about two to three times as long as a flu shot, a result of the procedures needed because the vaccine is stored in a deep freeze.
Patients need to socially distance before and after being given the vaccine and be monitored for allergic reactions.
The United States gives 170 million flu vaccinations each year within a few months, but for the Covid-19 pandemic, the US will need to provide about three times that number – the Pfizer and Moderna shots are two doses – to reach most Americans by July.
At the current pace, the US appears to have the capacity to administer fewer than a third of the doses shipped in a given week, underscoring the gap.
A spokesperson for Houston Methodist, a hospital in Houston, Texas, said it had given 8,300 employees the vaccine as of Monday with about 7,000 doses left from the first shipment.
The University of Southern California's Keck Medicine medical school vaccinated more than 3,000 employees and said it will take six weeks for everyone, similar to its flu-vaccination schedule.
States and health departments need federal money to hire staff, from data centre workers to track inoculations to call centre employees to field questions, said Adriane Casalotti, chief of government and public affairs of the National Association of County and City Health Officials.
The US Congress's coronavirus aid package sets aside more than $8 billion for vaccine distribution, but is delayed.
"You can't hire someone in December and train them up if you don’t know you can pay them in January," Ms Casalotti said.