The U.S. Is Rolling Out Monkeypox Vaccines & Here's How Each Of Them Works

The U.S. government announced on Tuesday that it will hand out 56,000 doses of monkeypox vaccine from its national stockpile immediately, amid a mysterious global outbreak of the virus.

Yes, you read that right: they're sitting on a stockpile of this stuff because, unlike with COVID-19, they've already got vaccines for both monkeypox and smallpox, its more dangerous cousin.

The White House also said that it will distribute an additional 240,000 doses over the coming weeks.

The FDA-approved vaccines will be given out to people at high risk of getting monkeypox or those who have been exposed to someone with it, the government says.

The U.S. has now recorded more than 300 cases in recent months, according to CDC data — none of which have resulted in death. Men who have sex with men have been disproportionately affected during this outbreak, but it is not primarily transmitted sexually.

The CDC is recommending the doses be given to individuals with a confirmed or presumed exposure, including those who have had "close physical contact" or are sexual partners with a confirmed case, and men who have recently had multiple male sex partners in "a venue where there was known to be monkeypox or in an area where monkeypox is spreading."

There are actually two approved monkeypox/smallpox vaccines available, and they each work differently from the ones for COVID-19. The vaccines are about 85% effective in preventing monkeypox, the CDC says.

Here's what you need to know about them, according to the CDC.

The Jynneos vaccine

The first vaccine that U.S. officials are using is called Jynneos in the U.S., Imvamune in Canada, Imvanex in Europe or just MVA-BN.

Canada and the U.S. approved it for use against monkeypox in 2019, although it was being used against smallpox for years before that, the WHO says.

The vaccine is given out as two shots under the skin, with the second dose following four weeks after the first, according to the CDC.

There is "no visible 'take'" to the vaccine, according to the CDC, so you won't see any lesions at the spot where you got the needle.

The CDC says a person is not considered immune until 14 days after they get the second dose of this vaccine. However, it can still help to get a dose after exposure.

This vaccine uses a live virus, but it's "non-replicating," the CDC says.

Canadian officials say in their briefing about Imvamune that the vaccine doesn't contain actual smallpox, and it cannot cause or spread that disease.

The ACAM2000 vaccine

The second vaccine is called ACAM2000, and it's a little messier than the first.

According to the CDC, ACAM2000 is given by pricking the surface of the skin with a special needle, and it leaves a person with a lesion or "take" at the site.

While this vaccine doesn't contain any smallpox or monkeypox virus, it does contain a much milder virus from the same family. If you get this vaccine, you have to be careful with that lesion or you can spread the live virus to other parts of your body or to other people. That's because the virus is growing at the site as your body learns to fight it, the CDC says on its website.

It adds that you "must take precautions" to avoid spreading this virus after getting the vaccine. Basically, that means keeping it dry, clean and covered with a bandage that you change every few days, according to the CDC.

A person is considered vaccinated within 28 days after the inoculation.

The White House says this is the second-best vaccine after Jynneos, because there is a "greater risk of certain serious side effects." It's also from an earlier generation of smallpox vaccines.

Officials say they'll make sure that individuals know all the benefits and risks of this one before they hand it out.

This article's cover image was used for illustrative purposes only.