The distribution of vaccines in the USA has gotten off to a slower-than-expected begin, federal well being officers acknowledged in a information convention on Wednesday, although additionally they voiced confidence that the tempo would speed up within the coming weeks.

As of Wednesday, greater than 14 million doses of the Pfizer and Moderna vaccines had been despatched out throughout the USA, up from 11.4 million doses on Monday morning. However simply 2.1 million folks had obtained their first dose as of Monday morning, in accordance with a dashboard maintained by the Centers for Disease Control and Prevention.

“We agree that that quantity is decrease than what we hoped for,” stated Moncef Slaoui, scientific adviser of Operation Warp Pace, the federal effort to speed up vaccine improvement and distribution. He added, “We all know that it must be higher, and we’re working onerous to make it higher.”

The two.1 million administered doses reported by the C.D.C. is an underestimate of the true quantity due to lags in reporting. And a C.D.C. official stated in a separate information convention on Wednesday that 2.6 million folks had obtained their first dose. Regardless of the quantity, it falls far in need of the aim that federal officers put ahead as lately as this month to have 20 million folks vaccinated by the top of this 12 months.

The Operation Warp Pace information convention got here a day after President-elect Joseph R. Biden Jr. gave a speech in Wilmington, Del., criticizing the Trump administration for these delays. Mr. Biden stated that, on the present price of vaccination, “it’s going to take years, not months,” to guard your entire nation.

When he takes workplace on Jan. 20, Mr. Biden stated, he’ll use a legislation referred to as the Protection Manufacturing Act to “order non-public business to speed up the making of the supplies wanted for the vaccines in addition to protecting gear.” The Trump administration has already used that legislation to hurry manufacturing, nonetheless, and Mr. Biden has given few particulars about how his plan can be any completely different. He has promised to manage 100 million shots — or sufficient for about 50 million folks if utilizing the two-dose vaccines — within the first 100 days of his time period.

“That is going to be the best operational problem we’ve ever confronted as a nation,” Mr. Biden stated, “however we’re going to get it accomplished.”

In a tweet on Tuesday, President Trump appeared to put the blame on governors, saying that it was “as much as the States to distribute the vaccines as soon as dropped at the designated areas by the Federal Authorities.” However a number of governors have lately stated their states have struggled as a result of they’d not obtained sufficient cash from the federal authorities.

On the Operation Warp Pace information convention on Wednesday, Gen. Gustave F. Perna, the hassle’s logistics lead, stated his crew didn’t have a transparent understanding of why these delays have been taking place. He stated the C.D.C. was gathering information to raised perceive the components driving the gradual uptake. “To have larger specificity presently, after two weeks, I don’t assume could be acceptable,” he stated.

However Normal Perna pointed to some attainable contributing components. Along with the lags in reporting, the vacation season and winter climate have delayed uptake. Hospitals and different services administering the vaccines are nonetheless studying the best way to retailer the doses at very chilly temperatures and correctly administer them. And states have put aside many doses to be given out to their long-term care services, a drive that’s simply gearing up and anticipated to take a number of months.

To date, most vaccines administered have been given out at hospitals, clinics and nursing houses. Dr. Slaoui and Normal Perna each stated they anticipated the tempo of the rollout to speed up considerably as soon as pharmacies start providing vaccines of their shops.

The federal authorities has reached agreements with a number of pharmacy chains — together with Costco, Walmart and CVS — to manage vaccines of their shops and different places as soon as vaccines turn into extra broadly accessible. To date, 40,000 pharmacy places have enrolled in that program, Normal Perna stated.

“What we must be is the speed of acceleration over the approaching weeks,” Dr. Slaoui stated, “and I hope will probably be in the best route.”