The U.S. has distributed more than 11.4 million doses of the Pfizer and Moderna COVID-19 vaccines, and more than 2.1 million of those had been given to people as of December 28, according to the CDC.
The CDC’s COVID Data Tracker showed the updated numbers as of 9 a.m. on that day. The distribution total is based on the CDC’s Vaccine Tracking System, and the administered total is based on reports from state and local public health departments, as well as updates from five federal agencies: the Bureau of Prisons, Veterans Administration, Department of Defense, Department of State, and Indian Health Services.
Health care providers report to public health agencies up to 72 hours after the vaccine is given, and public health agencies report to the CDC after that, so there may be a lag in the data. The CDC’s numbers will be updated on Mondays, Wednesdays, and Fridays.
“A large difference between the number of doses distributed and the number of doses administered is expected at this point in the COVID vaccination program due to several factors,” the CDC says.
Delays could occur due to the reporting of doses given, how states and local vaccine sites are managing vaccines, and the pending launch of vaccination through the federal Pharmacy Partnership for Long-Term Care Program.
“Numbers reported on other websites may differ from what is posted on CDC’s website because CDC’s overall numbers are validated through a data submission process with each jurisdiction,” the CDC says.
On Dec. 26, the agency’s tally showed that 9.5 million doses had been distributed and 1.9 million had been given, according to Reuters.
Public health officials and health care workers have begun to voice their concerns about the delay in giving the vaccines.
“We certainly are not at the numbers that we wanted to be at the end of December,” Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases, told CNNDec. 29.
Operation Warp Speed had planned for 20 million people to be vaccinated by the end of the year. Fauci said he hopes that number will be achieved next month.
“I believe that as we get into January, we are going to see an increase in the momentum,” he said.
Shipment delays have affected other priority groups as well. The New York Police Department anticipated a rollout Dec. 29, but it’s now been delayed since the department hasn’t received enough Moderna doses to start giving the shots, according to the New York Daily News.
“We’ve made numerous attempts to get updated information, and when we get further word on its availability, we will immediately keep our members appraised of the new date and the method of distribution,” Paul DiGiacomo, president of the Detectives’ Endowment Association, wrote in a memo to members on Dec. 28.
“Every detective squad has been crushed with [COVID-19],” he told the newspaper. “Within the last couple of weeks, we’ve had at least two detectives hospitalized.”
President-elect Joe Biden will receive a briefing from his COVID-19 advisory team, provide a general update on the pandemic, and describe his own plan for vaccinating people quickly during an address Dec. 29, a transition official told Axios. Biden has pledged to administer 100 million vaccine doses in his first 100 days in office.
A version of this article originally appeared on WebMd.