Mpox Vaccine Well-Tolerated in Adolescents | ID Week 2024

Modified vaccinia Ankara-Bavarian Nordic (MVA-BN), a vaccine to prevent mpox infection, showed immune response in adolescents similar to that of adults with no safety signals six months after the last dose, according to interim results from a U.S. phase 2 trial. Results were presented at ID Week 2024, which is being held this week in Los Angeles.

Catherine Mary Healy, M.D.

“This opens the stage to possibly using this vaccine more widely on the global stage,” Catherine Mary Healy, M.D., associate professor of Pediatrics Infectious Diseases at Baylor College of Medicine and Texas Children’s Hospital, said during a press conference ahead of the meeting. “The best way to prevent mpox is through vaccination. However, there’s only one licensed vaccine, MVA-BN.”

MVA-BN is marketed as Jynneos in the United States for those 18 years of age and older. The vaccine is also marketed as Imvanex in Europe and the United Kingdom also for those over the age of 18. Last month, the European Commission for Medicinal Products approved Imvanex as a smallpox and mpox vaccine, extending the current marketing authorization to include adolescents 12 to 17 years of age.

Mpox is a viral infection that can spread mainly through close contact and results in a painful skin rash and other symptoms. Most people recover, but in some people, the infection can lead to serious disease.

The rapid spread of the newest mpox strain, clade 1b, has caused the World Health Organization (WHO) in August 2024 to declare it a public health emergency of international concern. The Democratic Republic of the Congo has reported more than 30,000 suspected cases and more than 900 deaths, according to UNICEF. The current outbreak in affected countries also includes high-risk groups such as pregnant women and children under the age of 18 years, including infants.

The World Health Organization has prequalified the vaccine and said that it could be used off-label in infants, children and adolescents, and in pregnant and immunocompromised people in outbreak settings.

Buddy Creech, M.D.

“Vaccination will be an important next step in controlling the ongoing spread of impacts, particularly in areas like the DRC,” Buddy Creech, M.D., Edie Carell Johnson Chair in Pediatrics and professor of Pediatrics at Vanderbilt University Medical Center, said during the press conference. “The DRC launched its first vaccination campaign against mpox in the city of Goma, which has experienced ongoing transmission.”

Creech said the vaccine will be first given to healthcare workers and to those with underlying health conditions, and at least 200,000 to 300,000 doses will be made available. Bavarian Nordic, the manufacturer of the vaccine, recently signed an agreement with UNICEF for 1 million mpox vaccine doses. Combined with other efforts, including an agreement with GAVI, there are about 2.5 million doses available to assist the efforts to control the spread of mpox.

At ID Week, researchers presented interim data from the phase 2 trial of the MVA-BN vaccine. Researchers assessed the vaccine in 315 adolescents 12 to 17 years of aged compared with the vaccine given to 211 adults 18 years and older. They found that overall, the MVA-BN was well tolerated. Dizziness was more common in adolescents (3% versus none in adults) but similar to rates reported after other adolescent vaccines.

Bavarian Nordic is preparing for a clinical trial to assess the safety of MVA-BN in children 2 to 12 years of age. The trial, partially funded by the Coalition for Epidemic Preparedness Innovations (CEPI).

CEPI has also co-funded a clinical study, led by McMaster University in Canada, to assess post-exposure vaccination with MVA-BN, i.e. if the vaccine helps reduce the risk of secondary mpox cases, or, in case of mpox infection, can reduce the severity of illness. The study will include more than 1.500 people, including children in the DRC, Uganda and Nigeria.