As monkeypox cases continue to grow across the country, demand for the vaccine has been "overwhelming"—leading the Biden administration on Friday to purchase an additional 2.5 million vaccine doses to increase the currently limited supply.

How the US plans to vaccinate against monkeypox

Demand for monkeypox vaccines outstrips supply

Currently, CDC has reported over 1,800 confirmed monkeypox cases across 43 U.S. states and the District of Columbia. And as monkeypox cases continue to increase nationwide, demand for the vaccine has far outstripped supply, particularly in areas with a high concentration of cases, such as New York City and San Francisco.

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"The demand has been very, very high—overwhelming, at this point," said Mary Foote, from the New York City health department. "We just want to make clear: If we have the vaccine, we can administer it. The critical issue here right now is supply."

So far, CDC has distributed 156,000 doses of the Jynneos vaccine nationwide, and an additional 131,000 doses are expected to be available for order as soon as Monday. In addition, while there is ample supply of an alternative vaccine, ACAM2000, that can be used to prevent monkeypox, it is associated with serious side effects, and relatively few states have requested doses of it.

According to several health experts, this vaccine shortfall, along with limited access to diagnostic testing, has severely limited the United States' efforts to control the current monkeypox outbreak.

"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."

US expands testing, vaccine supply

Recently, CDC partnered with several commercial testing labs, include Quest Diagnostics and Labcorp, to significantly increase the United States' testing capacity from 6,000 tests a week to 70,000 tests a week. According to CDC Director Rochelle Walensky, the country's lab network for monkeypox has experienced a 76% increase in the number of tests conducted since July 6.

"The ability of commercial labs to test for monkeypox is a key pillar in our comprehensive strategy to combat this disease," Walensky said. "This will not only increase testing capacity but will make it more convenient for providers and patients to access tests by using existing provider-to-lab relationships."

Currently, monkeypox tests are conducted using pus from lesions, but CDC is considering whether tests based on saliva, throat swabs, or blood could also be used to detect monkeypox. According to the New York Times, this would allow people who are asymptomatic or not yet symptomatic to get tested for the virus.

"The faster you can identify cases, the better you are at isolating them and preventing onward transmission," Rimoin said.

In addition to expanding testing capacity, the Biden administration on Friday ordered an additional 2.5 million doses of the Jynneos vaccine, bringing the country's total supply to roughly 7 million. According to HHS, the total supply of monkeypox vaccines is expected to be available by mid-2023.

"We're working around the clock to increase supply and make sure we're reaching those most at risk," said Dawn O'Connell, assistant secretary for preparedness and response at HHS.

Going forward, Walensky said the federal government plans to focus on getting vaccines to areas with growing case counts "while still providing vaccines to all jurisdictions and individuals at increased risk for disease.

"We have tests, we have vaccines, we have therapies, we're building up our capacity on all of them, and they are going to become more and more readily available to the American people," said Ashish Jha, the White House Covid-19 coordinator. "We're going to get our arms around this thing." (Anthes, New York Times, 7/18; Mahr, Politico, 7/15; Diamond, Washington Post, 7/15; Perrone, Associated Press, 7/14; Twenter, Becker's Hospital Review, 7/15; Weintraub, USA Today, 7/15)