The slow roll-out is a blow to chances of containing the outbreak, health experts warn.
US health officials say they do not have enough monkeypox vaccines to cope with surging demand.
The US has seen more than 1,800 cases so far, though that is thought to be an undercount as testing has also lagged.
There has been growing concern about the rate at which monkeypox is spreading – especially in New York City, epicentre of the US outbreak.
The disease, characterised by lesions on the skin, usually clears up on its own but can be extremely painful.
Most confirmed cases have been among men who have sex with men, although anyone can be infected with the virus.
“We don’t yet have all the vaccine that we would like in this moment,” US Centers for Disease Control director Rochelle Walensky told a news briefing on Friday.
The US has received 370,000 out of nearly 7m vaccine doses that the government has purchased in total. But millions of the doses are not expected to arrive until next year.
The federal government has distributed about 156,000 doses nationwide and expects to start shipping another 130,000 doses from Monday, according to the US Department of Health and Human Services.
Earlier this week, New York city’s vaccinations website crashed as thousands of people tried to book vaccine appointments at once.
New York City Health Commissioner Ashwin Vasan apologised for the patchy roll-out of the vaccine.
“We own it. You know, those mistakes shouldn’t happen and so we’re working to correct those and do better,” he said at a news conference.
During a call on Tuesday with Biden administration officials, New York Mayor Eric Adams asked for the city to be allocated more doses.
The true scope of the US outbreak is unknown as diagnostic testing has lagged and it can take up to three weeks for symptoms to appear. A month ago the US had just 45 cases.
“We’re still having problems with availability of testing and vaccine supply, all these issues that we saw with Covid,” Gregg Gonsalves, an associate professor of epidemiology at the Yale School of Public Health, told Kaiser Health News last week. “Now, the prospects for containment are receding quickly.”
The US has bought more than 1.1m doses of the Jynneos vaccine produced by Bavarian Nordic in Denmark.
Hundreds of thousands more doses are expected to arrive soon in the US after American federal health officials said they had completed an inspection of the Danish plant.
More than 12,500 cases of monkeypox have been reported in nearly 70 countries, according to the US Centers for Disease Control.