Use of JYNNEOS (Smallpox and Monkeypox Vaccine, Live, Nonreplicating) for Preexposure Vaccination of Persons at Risk for Occupational Exposure to Orthopoxviruses

Recommendations of the Advisory Committee on Immunization Practices -- United States, 2022

Agam K. Rao, MD; Brett W. Petersen, MD; Florence Whitehill, DVM; Jafar H. Razeq, PhD; Stuart N. Isaacs, MD; Michael J. Merchlinsky, PhD; Doug Campos-Outcalt, MD; Rebecca L. Morgan, PhD; Inger Damon, MD, PhD; Pablo J. Sánchez, MD; Beth P. Bell, MD


Morbidity and Mortality Weekly Report. 2022;71(22):734-742. 

In This Article


During January 2020–November 2021, the ACIP Orthopoxvirus Work Group participated in monthly or bimonthly teleconferences to consider the evidence for five questions: 1) should JYNNEOS be recommended for research laboratory personnel, clinical laboratory personnel performing diagnostic testing for orthopoxviruses, and designated response team members at risk for occupational exposure to orthopoxviruses; 2) should JYNNEOS be recommended for health care personnel who administer ACAM2000 or care for patients infected with replication-competent orthopoxviruses; 3) should persons who are at ongoing risk for occupational exposure to more virulent orthopoxviruses such as Variola virus or Monkeypox virus receive a booster dose of JYNNEOS every 2 years after the primary JYNNEOS series; 4) should persons who are at ongoing risk for occupational exposure to less virulent replication-competent orthopoxviruses such as Vaccinia virus or Cowpox virus receive a booster dose of JYNNEOS at least every 10 years after the primary JYNNEOS series; and 5) should persons who are at ongoing risk for occupational exposure to orthopoxviruses and who received an ACAM2000 primary vaccination have the option to receive a booster dose of JYNNEOS as an alternative to a booster dose of ACAM2000. The Work Group comprised experts in diverse disciplines, including laboratory, public health, infection control, preparedness, and various clinical specialties (e.g., infectious disease, obstetrics, and occupational health). Federal partners represented on the Work Group included FDA, the National Institutes of Health, the U.S. Department of Defense, and the U.S. Department of Health and Human Services-Biomedical Advanced Research and Development Authority. CDC contributors also joined Work Group meetings with subject matter expertise in orthopoxviruses, regulatory affairs, laboratory diagnostic testing, vaccine adverse events, and drug services. Data collected, analyzed, and prepared by the Work Group were deliberated by ACIP during four public meetings.

Subject matter experts performed a systematic review and metaanalysis of the published literature on August 12, 2020, to inform the recommendations; the review was not limited by date or language. The Work Group used a modified Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to determine the certainty of evidence rated on a scale of 1 (high certainty) to 4 (very low certainty) for the following desirable and undesirable outcomes deemed critical for decision-making: prevention of disease, incidence of serious adverse events, and incidence of myopericarditis; prevention of disease was defined as prevention of an orthopoxvirus infection. Although no level of antibody protection for orthopoxviruses has been established, the detection of neutralizing antibodies after JYNNEOS is an indirect measure of protection (i.e., immunogenicity). Immunogenicity that peaks 2 weeks after completion of the 2-dose series (i.e., 6 weeks after the first vaccine in the 2-dose series) is called primary immunogenicity. Within the evidence to recommendations (EtR) framework, ACIP considered the importance of orthopoxvirus infection as a public health problem; the benefits and harms (including the graded evidence); the target populations' values and preferences; and issues of resource use, acceptability to stakeholders, feasibility of implementation, and anticipated impact on health equity.