Baylor College of Medicine

Abstract representation of the virus monkeypox
The image shows an abstract representation of the monkeypox virus

Monkeypox vaccine trial recruiting volunteers

Dipali Pathak


Houston, TX -

The Vaccine and Treatment Evaluation Unit at Baylor College of Medicine has been selected by the National Institutes of Allergy and Infectious Diseases (NIAID), a part of the National Institutes of Health (NIH), as one of the sites for a clinical trial to evaluate alternative strategies for administering the JYNNEOS monkeypox vaccine to increase the number of doses available. Baylor’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 the NIH.

The trial will enroll more than 200 adults across eight U.S. research sites. JYNNEOS is manufactured by Bavarian Nordic, based in Copenhagen and is approved by the U.S. Food and Drug Administration (FDA) for the prevention of smallpox and monkeypox disease in adults 18 years of age and older determined to be at high risk for smallpox or monkeypox infection.

“We hope that this vaccine trial will allow us to extend the vaccine supply of the JYNNEOS monkeypox vaccine, and hence be able to vaccinate more persons who need it,” said Dr. Hana El Sahly, professor of molecular virology and microbiology and of medicine – infectious diseases at Baylor and principal investigator of Baylor’s trial site.

JYNNEOS contains an attenuated orthopoxvirus called modified vaccinia Ankara, which does not replicate in human cells. It is approved for administration by two subcutaneous (in the tissue beneath the skin) injections 28 days apart; however, the FDA recently authorized intradermal (between layers of the skin) administration of the vaccine for adults. This alternative intradermal dosing regimen uses one-fifth of the standard dose used for subcutaneous administration, allowing healthcare providers to administer up to five times the number of vaccine doses per vial of JYNNEOS vaccine. NIH-supported researchers demonstrated in a 2015 publication that intradermal administration at one-fifth of the standard dose induced an immune response in recipients that was comparable to the subcutaneous method of administration.

Adults ages 18 to 50 years who have not been vaccinated against smallpox or monkeypox previously are eligible to enroll in the trial. Investigators aim to include a demographically diverse group of volunteers that represents those affected by monkeypox. All trial participants will receive the JYNNEOS vaccine in some form. Participants will be assigned at random to one of three study arms:

  • One arm will receive the standard, licensed regimen of 1x108 infectious virus particles administered subcutaneously.
  • Another arm will receive 2x107 infectious virus particles (one-fifth of the standard regimen) administered intradermally, the regimen recently authorized by the FDA.
  • A third arm will receive one-tenth (1x107 infectious virus particles) of the standard regimen of JYNNEOS administered intradermally.

Investigators will assess whether the peak immune responses induced in recipients receiving the vaccine intradermally are equivalent to those induced by the licensed subcutaneous regimen and will compare the relative safety and tolerability of the different regimens.

Volunteers will be asked to participate in eight study visits over the course of a year where they will undergo physical examinations and provide blood samples for laboratory evaluations. An independent Data and Safety Monitoring Board will monitor participant safety throughout the duration of the study.

Investigators anticipate the trial will take 15 months to complete; however, initial results could be available in early 2023. For more information, please visit and search identifier NCT05512949.

To enroll in the vaccine trial at the Baylor site, or call 713-798-4912.

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