FDA Approves Smallpox Vaccine to Prevent Mpox

mpox vaccine vial © Andreas Prott - stock.adobe.com

The FDA approved the expansion of Emergent BioSolutions’ smallpox vaccine (ACAM2000) to prevent mpox in light of the recent global emergency declared by World Health Organization's (WHO), according to a news release published yesterday. Emergent BioSolutions will also donate 50,000 doses pending deployment to impacted countries in Central Africa.

“Mpox has progressed to become an uncontrolled epidemic in Africa — prompting the WHO to declare a second public health emergency of international concern — creating an enormous need to use all effective tools to extinguish it as a threat,” Amesh A. Adalja, M.D., FIDSA, a health security and emerging infectious diseases expert at Johns Hopkins Center for Health Security said in the news release. “ACAM2000, a direct descendant of the Jenner vaccine (humanity’s first), which was used to eradicate smallpox, and now with the broadened indication, will be an invaluable tool in this endeavor.”

It is a single dose vaccine administered using a bifurcated needle dipped into the vial. The skin on the upper arm is then pricked 15 times. Because it is a live vaccine, it is not recommended for people with severe immunodeficiency. Those patients should receive the JNNYEOS vaccine instead, which was the first vaccine approved in 2019 to prevent Mpox.

ACAM2000 was first approved in 2007 for the prevention of smallpox, and in 2022, it was made available for mpox under an Expanded Access Investigational New Drug protocol. In 2022, the mpox outbreak led to more than 95,000 cases across 115 countries.

The latest mpox strain, clade 1b, is primarily spreading in the Democratic Republic of Congo where there have been more than 15,600 cases and 537 deaths recorded.It has also begun to spread rapidly to neighboring countries Burundi, Kenya, Rwanda and Uganda where mpox has not yet been seen. More than 100 mpox cases have been reported in these countries. A case was recently reported in Sweden as well. Clade 1b is highly contagious and it most commonly spreads during sexual contact between men who have sex with men.

Mpox was first discovered in 1958 when researchers noticed a pox-like disease spreading through the monkeys they kept for research. The first human case of mpox was found in 1970 in the DNC.