Public health agency The US Food and Drug Administration announced on Tuesday that it has approved the Jynneos Smallpox and Monkeypox Vaccine, Live, Non-Replicating, for the prevention of smallpox and monkeypox disease in adults 18 years of age and older determined to be at high risk.

The agency granted the approval of Jynneos to Bavarian Nordic A/S. under its priority review and priority review voucher.

Part of the Strategic National Stockpile (SNS), the Jynneos will be available for those determined to be at high risk of either smallpox or monkeypox infection. The availability of this vaccine in the SNS will help ensure that the vaccine is accessible in the US if needed.

Smallpox, which is caused by the variola virus, is a highly contagious and often fatal infectious disease. Monkeypox is a rare disease caused by infection with monkeypox virus. Monkeypox is transmitted to people from various wild animals, rodents and primates.

Jynneos is made from a vaccinia virus, which is closely related to, but less harmful than, variola or monkeypox viruses and can protect against both of these diseases. Jynneos contains a modified form of the vaccinia virus called Modified Vaccinia Ankara, which does not cause disease in humans and is non-replicating in human cells, added the agency.

In conjunction, the effectiveness of the company's Jynneos for the prevention of smallpox was determined in a clinical study that included approximately 400 healthy adults, 18 through 42 years of age who had never been vaccinated for smallpox. The effectiveness of Jynneos for the prevention of monkeypox disease is inferred from the antibody responses in the smallpox clinical study participants and from studies in non-human primates that showed protection of animals vaccinated with Jynneos who were exposed to the monkeypox virus.