FDA approves first live vaccine for smallpox, monkeypox prevention


The Food and Drug Administration has approved Jynneos, a live, nonreplicating vaccine based on the vaccinia virus, for smallpox and monkeypox, becoming the first FDA-approved vaccine for the prevention of monkeypox disease.

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FDA approval for Jynneos for smallpox is based on results from a clinical trial that compared Jynneos with ACAM2000, a previously FDA-approved smallpox vaccine, in about 400 healthy adults aged 18-42 years. Adults who received Jynneos had a noninferior immune response to those who received ACAM2000. In addition, safety was assessed in 7,800 people who received at least one vaccine dose, with the most commonly reported side effects including pain, redness, swelling, itching, firmness at the injection site, muscle pain, headache, and fatigue.

The effectiveness of Jynneos to prevent monkeypox – a disease similar to but somewhat milder than smallpox caused by the non–U.S.-native monkeypox virus – was inferred from antibody responses of participants in the smallpox clinical trial and from studies on nonhuman primates that showed protection from the monkeypox virus after being vaccinated with Jynneos.

“Routine [smallpox] vaccination of the American public was stopped in 1972 after the disease was eradicated in the U.S. and, as a result, a large proportion of the U.S., as well as the global population has no immunity,” said Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research. “Although naturally occurring smallpox disease is no longer a global threat, the intentional release of this highly contagious virus could have a devastating effect.”

This vaccine is also part of the Strategic National Stockpile, the nation’s largest supply of potentially lifesaving pharmaceuticals and medical supplies for use in a public health emergency, according to the announcement.

Find the full press release on the FDA website.

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