The Centers for Disease Control and Prevention published new guidance related to the ongoing monkeypox outbreak, recommending available smallpox vaccines effective against the new virus for certain healthcare workers.

The CDC’s Advisory Committee on Immunization Practices is responsible for issuing the edict on Friday. It's targeted primarily toward lab workers who research orthopoxviruses and healthcare personnel treating those infected.

The body recommends using the ACAM2000 vaccine and the newer Jynneos alternative, which the ACIP In November 2021 unanimously approved.

“With these recommendations for use of Jynneos, two vaccines (ACAM2000 and Jynneos) are now available and recommended for preexposure prophylaxis against orthopoxvirus infection among persons at risk for such exposures,” the CDC wrote.

The World Health Organization had declared smallpox eradicated in 1980 after a successful 20-year campaign to distribute vaccines. Since the last confirmed natural case in 1977, countries worldwide have ditched requirements for the vaccine, including the U.S.

However, with the monkeypox outbreak spreading, the CDC said Monday that it was planning to distribute the smallpox shots to the most high-risk groups, according to Fierce Pharma.

The CDC has reported nine positive virus cases in the U.S. Globally, health officials have detected more than 300 cases across around 24 countries. According to the Daily Mail, most detected cases have been in gay and bisexual men.