Saint Louis University’s (SLU) Center for Vaccine Development researchers are set to commence a Phase II clinical trial of the JYNNEOS mpox, which was previously known as monkeypox vaccine.

The team is inviting volunteers aged 12 to 17 and 18 to 50 for taking part in the national clinical trial, which is sponsored by the National Institutes of Health’s National Institute of Allergy and Infectious Diseases (NIAID).

This trial will evaluate the immune response and safety after two JYNNEOS doses are given subcutaneously to adolescents compared to adults.

JYNNEOS is said to be the only vaccine approved by the Food and Drug Administration (FDA) for mpox and demonstrated a well-known safety profile in adult subjects.

At present, the vaccine is only licensed for use in adults. The trial is aimed at studying whether the licensed dose is safe and elicits immune responses.

The participation of SLU is funded through a contract with Frederick National Laboratory for Cancer Research, which is operated by Leidos Biomedical Research in Frederick, Maryland, US.

Saint Louis University Center for Vaccine Development clinical director Sharon Frey said: “While mpox isn’t as deadly as smallpox, it is a serious illness that causes painful lesions.”

Frey is also the principal investigator of the trial for which the SLU Vaccine Center will enrol volunteers.

Adolescent subjects aged between 12 and 17 should not have previously received a mpox or smallpox vaccination or had mpox.

Participation in the clinical trial is expected to last around 13 months.