With monkeypox cases still on the rise, the Biden administration unveiled an "enhanced nationwide vaccination strategy" to help limit the spread of the disease, making 1.6 million vaccine doses broadly available to at-risk groups by the end of the year.

Monkeypox: The latest on the outbreak

US to expand access to monkeypox vaccine

Currently, CDC has confirmed 351 cases of monkeypox across 27 states and the District of Columbia. The Biden administration on Tuesday announced that it will increase the availability of the monkeypox vaccine.

Initially, health officials followed a ring vaccination model with monkeypox, only offering the vaccine to people who had high-risk contact with an infected patient. But now, the vaccine will be offered more broadly to at-risk groups, after Canada and the United Kingdom unveiled similar strategies.

Specifically, the vaccine campaign will focus largely on men who have sex with men (MSM) who are in geographic areas where monkeypox is spreading readily. Health officials said those who have had a sexual partner diagnosed with monkeypox, as well MSM with multiple sexual partners in areas where monkeypox cases are rising, should get vaccinated.

According to health experts, the current outbreak may be primarily affecting MSM because highly interconnected sexual networks may allow the virus to spread more easily than it would in the general population.

According to Jennifer McQuiston, deputy director of CDC's division of high consequence pathogens and pathology, the new vaccine strategy redefines who is considered a contact of a monkeypox patient.

"We've always wanted to recommend vaccine to known contacts of monkeypox cases. But in a setting where you may not be able to actively or expediently identify all contacts, we're considering as contacts people who may have had the type of exposure recently that would put them at high risk for monkeypox," she said. "Whether they participated at a party or a venue where monkeypox was known to spread, but we can't trace them, we recommend they come in for a vaccine."

To ensure the most protection, CDC Director Rochelle Walensky recommended people be vaccinated within two weeks of a possible exposure, "and the sooner you can get vaccinated after the exposure, the better."

1.6M vaccine doses expected by the end of the year

During the initial vaccine rollout, HHS will immediately release 56,000 doses of the Jynneos vaccine, the preferred vaccine against monkeypox, through a tiered approach to prioritize areas with the highest number of cases. So far, 32 states and jurisdictions have requested vaccines, and more than 9,000 doses, along with 300 antiviral treatments, have been sent out.

"This vaccine currently has some limitations on supply, and for this reason the administration's current vaccine strategy prioritizes making it available to those who need it most urgently," Walensky said.

Over the next few weeks, around 240,000 additional vaccines will be made available. In addition, a further 750,000 vaccine doses will be delivered during the summer, and 500,000 more doses will be available throughout the fall—totaling 1.6 million available doses by the end of the year.

In addition to the Jynneos vaccine, health officials said they are also making ACAM2000, an older smallpox vaccine that can also be used for monkeypox, available for states to order if necessary. More than 100 million doses of ACAM2000 are available, but it has the potential for adverse side effects and cannot be given to certain vulnerable groups, including those who are immunocompromised.

According to Walensky, as more doses of the Jynneos vaccine become available, officials may consider shifting their response to a pre-exposure, instead of post-exposure, approach.

"As soon as we have more vaccines available, we will of course continue to expand from a post-exposure prophylaxis strategy ideally to a pre-exposure prophylaxis strategy," she said. "I do think it would be wise to address that expansion at a time when we have more vaccine so we can really follow where the outbreak is densest."

Experts criticize officials' slow monkeypox response

So far, health experts have criticized the administration's monkeypox vaccination campaign, saying that it is too small and slow to effectively curb the growing outbreak in the United States. In areas that have started rolling out small vaccination campaigns, demand has already outpaced supply.

"Everything [the CDC] is doing, they should have done weeks ago," says Ali Khan, a former CDC official who is now at the University of Nebraska.

"Many of us are concerned that the window is closing for us to be able to eliminate monkeypox,” said Celine Gounder, an infectious disease expert and editor-at large for public health at Kaiser Health News.

"If we don't start vaccinating more quickly and broadly, we're going to have a very difficult time containing this," she said. According to Gounder, tests and vaccines could have ideally been offered at LGBTQ Pride events to reach people at high risk of contracting monkeypox.

In addition, some experts have voiced concerns about whether there will be enough of the Jynneos vaccine to effectively protect everyone at risk, especially individuals who have HIV and cannot be given the older smallpox vaccine.

"There won't be enough to meet the need,” said Elizabeth Finley, director of communications for the National Coalition of STD Directors. "Plus, without better testing capacity, a strategy based on contacts with a positive case falls flat."

Still, "the current plan is absolutely appropriate for what we're currently seeing," Khan added. "It goes as far as you would go, based on the available information," by focusing on education, testing and vaccination in high risk groups. (Mendoza, USA Today, 6/28; Branswell, STAT News, 6/28; Mahr, Politico, 6/28; Weixel, The Hill, 6/28; Diamond et al., Washington Post, 6/28; Stone/Huang, NPR, 6/28; Mandavilli, New York Times, 6/28; Dreher, Axios, 6/28)