FDA Approves Vaccine Against Smallpox, Monkeypox

Troy Brown, RN

September 24, 2019

The US Food and Drug Administration (FDA) has approved Jynneos Smallpox and Monkeypox Vaccine, Live, Non-Replicating , (Bavarian Nordic A/S) for the prevention of smallpox and monkeypox disease in adults aged at least 18 years who have a high risk for either infection.

It is currently the only vaccine approved by the FDA for monkeypox prevention and it is the first live, nonreplicating vaccine to prevent both diseases.

"Following the global Smallpox Eradication Program, the World Health Organization certified the eradication of naturally occurring smallpox disease in 1980. Routine 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," Peter Marks, MD, PhD, director of the FDA's Center for Biologics Evaluation and Research, said in a news release.

"Therefore, although naturally occurring smallpox disease is no longer a global threat, the intentional release of this highly contagious virus could have a devastating effect. Today's approval reflects the U.S. government's commitment to preparedness through support for the development of safe and effective vaccines, therapeutics, and other medical countermeasures."

The vaccine is intended for individuals found to have a high risk for either smallpox or monkeypox infection. It is included in the Strategic National Stockpile, the largest supply of potentially life-saving drugs and medical supplies in the country for use during a public health emergency severe enough to exhaust local supplies.

Including it in the Strategic National Stockpile will help keep the vaccine available in the United States if it is needed.

Smallpox is a very contagious, often deadly, infectious disease caused by the variola virus; it was first seen in humans thousands of years ago. Infected individuals develop pus-filled pocks on the face and body. It is transmitted via saliva and respiratory droplets or by direct or indirect contact with the shedding virus. Smallpox can also be transmitted through other body fluids and contaminated clothes and bed linens.

Monkeypox is a rare infection caused by the monkeypox virus that results in similar but milder symptoms than smallpox but which can also be fatal. Symptoms include fever, headache, myalgia, and exhaustion. Wild animals including rodents and primates spread the disease.

The first reports of human monkeypox outside of Africa were seen in 2003, when an outbreak occurred in the United States.

A Two-Dose Vaccine

The viruses that cause smallpox or monkeypox are not used in this vaccine. The vaccine contains a modified vaccinia virus known as Modified Vaccinia Ankara, which is closely related to, but less dangerous than, variola or monkeypox viruses and is effective against both infections. It is nonreplicating; therefore, it is unable to reproduce in human cells and does not cause infection in humans.

The approval follows consideration of efficacy data from a clinical study that evaluated immune responses in approximately 400 adults aged 18 through 42 years with no prior smallpox vaccination.

Participants received either two doses of Jynneos spaced 28 days apart or a one-time dose of ACAM2000, an FDA-approved smallpox vaccine. The immune responses of those in the Jynneos group were not inferior to those of participants in the ACAM2000 group.

Researchers also inferred vaccine effectiveness against smallpox from supportive studies in nonhuman primates that found that prior vaccination with Jynneos protected against viruses related to smallpox.

For monkeypox disease prevention, the vaccine's effectiveness is inferred from the antibody responses of participants in the smallpox clinical study and from studies that found that nonhuman primates immunized with this vaccination were protected against the monkeypox virus.

Safety data came from more than 7800 individuals who received one or more doses of the vaccine. The most frequently seen adverse effects were "pain, redness, swelling, itching, firmness at the injection site, muscle pain, headache and fatigue," according to the news release.

The researchers identified no safety concerns that would necessitate a Medication Guide. The vaccine is given in two doses administered 4 weeks apart.

The application was granted Priority Review by the FDA and the FDA issued a material threat medical countermeasure (MCM) priority review voucher to the company with this approval. "The Federal Food, Drug, and Cosmetic Act, as amended by the 21st Century Cures (Cures) Act, authorizes the FDA to award priority review vouchers to sponsors of approved material threat MCM product applications that meet certain criteria," the FDA explains in the news release.

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