GW Is Site of NIH Trial Evaluating Mpox Vaccine in Adolescents

The university is one of 18 clinical sites around the U.S. testing a vaccine for the disease previously known as monkeypox in youth.

April 19, 2023

Colorized transmission electron micrograph of monkeypox particles (green) found within an infected cell (pink and purple), cultured in the laboratory.

Colorized transmission electron micrograph of mpox particles (green) found within an infected cell (pink and purple), cultured in the laboratory. (NIAID)

The National Institutes of Health trial to evaluate the mpox (previously known as monkeypox) vaccine JYNNEOS has now entered the next stage and is studying the immune responses to and the safety of the vaccine in adolescents. The George Washington University is one of 18 clinical trial sites across the United States that have launched this stage testing the JYNNEOS vaccine.

The JYNNEOS vaccine was approved by the U.S. Food and Drug Administration for use in adults in 2019 and, in 2022, was authorized for use in people under 18 years of age on an emergency use basis. The latest stage of the trial, which is sponsored by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, will look to see if the vaccine is safe and triggers an immune response in adolescents ages 12 to 17 that is comparable to adults ages 18 to 50 years. GW’s participation is funded through a contract with Frederick National Laboratory for Cancer Research, operated by Leidos Biomedical Research in Frederick, Maryland, which provides scientific support to NIH.

“We are excited to have launched the next stage of this clinical trial, which can help determine if this vaccine can be used to protect adolescents should there be another large outbreak in the United States or some other part of the world,” said David Diemert, clinical director of the George Washington University Vaccine Research Unit and professor of medicine at the School of Medicine and Health Sciences (SMHS). 

The GW Vaccine Research Unit is a collaboration between the GW Medical Faculty Associates (MFA) and the departments of medicine and of microbiology, immunology and tropical medicine located at SMHS. The unit conducts clinical trials of experimental products that are being developed for the prevention of infectious diseases.

The clinical investigators at GW and the other sites plan to test 135 adults ages 18 to 50 who will serve as a comparison group in this stage of the study. The researchers will also recruit about 315 adolescents ages 12 to 17 years. All of the recruits will get the standard dose of the vaccine delivered subcutaneously, Diemert said.

The trial will last for 13 months and investigators will check for safety and to see if the antibody response in adolescents in the study are comparable to that of adults.

Mpox historically occurs in West and Central Africa, but in 2022, a large outbreak began in the U.S. and other countries around the world where mpox is uncommon. The virus spreads through close contact with an infected person or animal.

Although kids in the United States rarely get mpox, experts say children and teens can and do get this painful and sometimes deadly disease. 

“Having a safe and effective vaccine at the ready would help prepare the United States and other countries for the next outbreak of this disease,” Diemert said.

Interested volunteers can email [email protected], call (202) 994-1599, or visit for more details. Interested volunteers can also visit and search identifier NCT05740982 for more information about the trial, including a list of sites.