The United States has ordered nearly seven million doses in total, but most of them will not arrive for months.
As the monkeypox outbreak grows in the United States, demand for the vaccine is outstripping the nation’s supply, Dr. Rochelle Walensky, the director of the Centers for Disease Control and Prevention, said at a news briefing on Friday.
“We don’t yet have all the vaccine that we would like in this moment,” she said.
When the supply crunch will ease is unknown. The federal government made another 131,000 doses available to states and other jurisdictions on Friday. But the scope of the outbreak remains unclear, in part because diagnostic testing has been slow and limited.
Nearly 1,500 cases have been identified in the United States, primarily in men who have sex with men, and the figure is likely to rise in the coming weeks, Dr. Walensky said. Globally, more than 11,000 cases have been identified in 65 countries, she added.
“Our window of opportunity to control it is rapidly closing,” said Anne Rimoin, an epidemiologist and monkeypox expert at the University of California, Los Angeles. “There are probably a lot more cases out there than we’re aware of.”
The Department of Health and Human Services ordered an additional 2.5 million doses of the vaccine, known as Jynneos, on Friday, but those doses are not scheduled to arrive until next year.
A previously ordered 2.5 million doses should begin arriving late this year, officials said.
“It’s like saying we have a tanker of water coming next week when the fire is happening today,” said Gregg Gonsalves, an epidemiologist at the Yale School of Public Health.
Initially, for instance, monkeypox testing was extremely limited, and each diagnosis had to be confirmed by the C.D.C., creating delays that might have allowed the virus to spread unseen and unchecked.
“Now we’re in a situation where it’s going to be exceedingly difficult, with limited supplies of the vaccine and still some problems with testing, to get this under control,” Dr. Gonsalves said.
The C.D.C. has teamed up with five commercial testing companies to expand the nation’s testing capacity, which now stands at 70,000 samples per week, up from 6,000 at the beginning of the outbreak.
“We have the capacity for testing that we need and have made it easier to access,” Dr. Walensky said.
But health officials should be doing more active surveillance for the disease, experts said.
Officials should get out into the community and offer testing in venues that serve men who have sex with men, as well as in congregate settings, such as homeless shelters, in which the virus might spread, Dr. Gonsalves said.
The monkeypox test involves swabbing one of the lesions that typically accompany the disease, making it difficult to expand testing to people who do not have symptoms, Dr. Walensky said. “You do need to have a lesion in order to get a test,” she added.
New tests, including those that can detect the virus in asymptomatic people, are needed, Dr. Rimoin said, as is active surveillance in animal populations, which might become reservoirs for the virus.
The virus is unlikely to remain in the networks and communities in which it is currently spreading, she added, and expanding testing is particularly important given the limited vaccine supply.
“The faster you can identify cases, the better you are at isolating them and preventing onward transmission,” Dr. Rimoin said.
Jynneos, the only vaccine approved by the F.D.A. specifically for monkeypox, is given in two doses, 28 days apart. It is made by Bavarian Nordic, a small company in Denmark, and its global supply has been exceedingly limited.
The United States has purchased nearly seven million doses in total, but has received just 372,000 of them, Dawn O’Connell, the assistant secretary for preparedness and response at the Department of Health and Human Services, said on Friday. So far, 156,000 doses have been distributed nationally, she said.
State health officials can request an alternative vaccine known as ACAM2000, which was developed to prevent smallpox and should also provide protection against monkeypox, experts say. But that vaccine is associated with serious side effects, and the federal government has only provided it to “a few states in relatively modest quantities,” Ms. O’Connell said.
The Food and Drug Administration recently finished inspecting Bavarian Nordic’s manufacturing facility in Denmark and is deciding whether to approve an additional 780,000 doses made there.
“We’re diligently working to finish up our evaluation of the required information, anticipating the hopeful release of these doses before the end of July,” said Dr. Peter Marks, a top vaccine regulator at the F.D.A.
The United States is not considering shifting to a one-dose strategy to stretch the existing supply, he added. “We’re confident that we’ll have a supply of vaccine in order to be able to vaccinate with the second dose at the appropriate 28-day interval or close to it,” he said.
States and jurisdictions that are seeing high or increasing cases of monkeypox, and populations that are considered to be at high risk, will receive priority in the allocation of new vaccine doses, officials said.
“We are working around the clock to increase supply and make sure we’re reaching those most at risk,” Ms. O’Connell said.