Who Should Get a Monkeypox Vaccine?

How is the Jynneos vaccine given?

Instead of being injected beneath the skin like most other vaccines, the Jynneos vaccine is given between the layers of the skin, just underneath the top layer, similar to a tuberculosis skin test. This is a recent change health officials made to stretch vaccine supplies, while also making sure the vaccine remains effective.

“Just under the skin level, there is a host of immune cells that exist that can actually provide for an immune response with a much lower dose of the vaccine,” says Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota.

This form of delivery poses some challenges. As Osterholm points out, “it’s more art than it is a science.” If you go too deep with the specialized needle, he explains, “then you don’t get the benefit of those immune cells close to under the skin and you will have an inadequate vaccination.”

The CDC says it takes 14 days after the second dose of Jynneos for its immune protection to reach its maximum.

What are the side effects?

The side effects of the Jynneos vaccine are the reactions you’d expect, Kennedy says: “Pain at the injection site, maybe a little bit of a fever, you might get some muscle aches and pains, and all of that usually happens within the first couple of days after vaccination.”

That said, this vaccine hasn’t been used extensively, nor has it been studied in millions of people, Kennedy adds. “So severe adverse reactions may exist, they’re just very rare and we haven’t used the vaccine enough to detect them.” For most people who have been exposed to monkeypox, the risks from the disease are greater than the risks from the smallpox or monkeypox vaccine, the CDC says.

How well do they work?

Researchers are still trying to understand how well the vaccines work against monkeypox in the current outbreak (remember: Monkeypox is a rare disease), but previous studies from Africa suggest that the smallpox vaccine is at least 85 percent effective in preventing monkeypox.

Additional vaccine effectiveness studies are underway in the U.S., and early data released by the CDC suggests the vaccine does work to help reduce risk of infection. But until the data is more concrete and reflective of the current situation, health experts are recommending that people who get vaccinated continue to exercise caution and avoid direct skin-to-skin contact with someone who has monkeypox.

If I was vaccinated against smallpox, am I protected?

Routine smallpox vaccination stopped in the U.S. in 1972 after the disease was eradicated, but many older adults remember receiving a shot. It’s unclear how well a vaccine given so long ago protects you today, Osterholm says. For example, a recent report published in The Lancet found that a share of people who were vaccinated for smallpox when they were children went on to develop monkeypox.

“That doesn’t tell you how protective [the vaccine] is. It could mean that there are still people who are protected, and it could also mean that there are people who may get infected but have a much milder illness because of having previous vaccinations. So this is one of those areas we’re learning a lot about,” Osterholm says.

WHO says people younger than 40 to 50 years of age (depending on the country) may be more susceptible to monkeypox, since smallpox vaccination campaigns stopped after the disease was eradicated. More research is ongoing.

Where can you get a monkeypox vaccine?

If you’re interested in getting vaccinated — and the vaccine is free — talk to your primary care physician. Your local or state health department also may offer vaccine clinics.

What else can I do to protect against monkeypox?

Even if you’re not eligible for a monkeypox vaccine, you can do several things to protect yourself from getting infected. Chief among them: Avoid physical contact with someone who has an infection.

“If you’re in a household with someone that comes down with it, they should be doing their own laundry, they should be eating separately, they should be ideally staying in a separate room,” Kennedy says. This is because the virus can spread by bedding, towels and clothing used by an infected person, according to the CDC.

Also, consider holding off on any big events where there may be prolonged periods of skin-to-skin contact with other people (like music festivals or dance clubs), especially in areas experiencing high rates of spread. Keep an open line of communication with your sexual partners and discuss any symptoms you may have been experiencing. The CDC also offers tips for safer sex and social gatherings in light of the outbreak.

Finally — and this is sage advice to prevent any illness — wash your hands often, experts say. 

Rachel Nania writes about health care and health policy for AARP. Previously she was a reporter and editor for WTOP Radio in Washington, D.C. A recipient of a Gracie Award and a regional Edward R. Murrow Award, she also participated in a dementia fellowship with the National Press Foundation.

Editor's note: This story, originally published on August 22, 2022, has been updated to include new information.