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Amid the monkeypox outbreak that has spread to 10 people in eight states in the U.S., officials said in a White House press briefing that people who may have been exposed are now being offered vaccines. And many people in the U.S. received routine smallpox vaccines when they were younger, which may still provide some protection.
Although officials are still learning about the details of this particular monkeypox outbreak and how it has spread, vaccines will undoubtedly be a key part of containing it.
Will an old smallpox vaccine protect against monkeypox?
Regular smallpox vaccination in the U.S. ended in the 1970s. But a smallpox vaccine — even one you received decades ago — will likely still provide some protection from monkeypox. How much protection it might give you isn't clear yet, experts said.
"We do know that the smallpox vaccine does offer some protection against monkeypox," Dr. Daniel Uslan, co-chief infection prevention officer for UCLA Health and clinical chief of the UCLA Division of Infectious Diseases, told TODAY.
"But that protection is likely greatest in the months to years after the smallpox vaccine is given," he said. "And, of course, we have not been giving people smallpox vaccine for many decades in this country."
Those who received a smallpox vaccine many years ago will likely still be protected against that and monkeypox "because they would have memory cells that would offer protection," Michael Gale, Ph.D., an immunologist at the University of Washington, told TODAY. These cells, which include some T cells and B cells, facilitate one part of the immune response we get from a vaccine. And the protection that memory cells provide can last for many years after getting that vaccine.
Uslan agreed: "My suspicion is that they will have some protection, but we really don't know exactly how much yet," he said.
The bottom line? Even without clear answers, "if you've had a vaccination, you should be pleased you've had one if you're at any risk of getting infected," Dr. David Heymann, infectious disease epidemiologist and former assistant director-general for health security at the World Health Organization, told TODAY. He also emphasized that it's important to be aware of the symptoms of monkeypox, as well as your own exposure risks to prevent the spread.
Is there a vaccine for monkeypox? Can I get one now?
There are two vaccines used in the U.S. to prevent smallpox and monkeypox, but they are not available to the general public.
"(The smallpox vaccine) is only available through the CDC, which maintains a stockpile, so the vaccine would really only be deployed by CDC in specific circumstances that they deem appropriate," Uslan said. "It's not the kind of thing you can go to your local CVS or Walgreens and get, like a flu shot or COVID vaccine."
People who may be exposed to smallpox or monkeypox through occupational hazards, like researchers and health care workers in certain settings, can still get smallpox vaccines. And if there's reason to believe someone has been recently exposed to monkeypox or smallpox in an outbreak, getting them the vaccine can help prevent the infection from taking hold, Uslan said.
There are a few options available. First, there is the ACAM2000 vaccine, recommended by a CDC panel for use in those exposed to smallpox-like viruses since 2015. And, as of November 2021, the panel recommended the use of a second vaccine, Jynneos, specifically for monkeypox.
The CDC's stockpile also contains a third smallpox vaccine, the Aventis Pasteur Smallpox Vaccine. This one is considered investigational, but could be made available under an emergency use authorization if needed, the CDC explained.
What's next for this outbreak?
While it’s certainly concerning to see monkeypox spreading at this level outside of central and western Africa, experts told TODAY they don’t expect it to become the next pandemic. That’s because the virus that causes monkeypox is transmitted differently than the coronavirus. (This one typically only spreads through close contact and tends not to spread unless someone has symptoms.)
Additionally, this is a DNA virus, meaning won’t develop new mutations and variants the same way the RNA-based coronavirus does, Gale said.
“DNA viruses proofread when they replicate,” he explained. So the virus that causes monkeypox doesn’t undergo the same “error-prone replication” the coronavirus does, making the emergence of new and concerning variants much less likely.
And the fact that we already have vaccines that can prevent the spread of monkeypox is another point in our favor.