by Carolyn Chu, MD, MSc, AAHIVS, AAHIVM Chief Medical Officer

May 23, 2023

Featured Literature:

Dalton AF, Diallo AO, Chard AN, et. al.  CDC Multijurisdictional Mpox Case-Control Study Group.  Estimated effectiveness of JYNNEOS vaccine in preventing Mpox: a multijurisdictional case-control study—United States, August 19,2022-March 31, 2023.  MMWR Morb Mortal Wkly Rep.  2023 May 19;72(20):553-558.  PMID: 37200229.    

This study, conducted in 12 jurisdictions, evaluated Mpox vaccine effectiveness (VE) among MSM and transgender adults aged 18-49 years.  309 case-patients of confirmed or probable mpox virus or Orthopoxvirus diagnosis were matched to 608 control patients who had visited a sexual health, HIV care, or PrEP clinic.  Participants completed a survey to provide information on demographics, mpox diagnosis and vaccination (history was verified through state registries where available), immunocompromising conditions, and exposures.  Larger proportions of case- than control participants reported recent homelessness (7.9% vs. 2.7%), transactional sex (9.1% vs. 3.3%) and living with HIV (48.1% vs. 24%).  Among participants who did not report living with HIV, a smaller proportion of case participants reported PrEP use (54.4% vs. 66.8%).  Larger proportions of case participants reported an immunocompromising condition or medication (46.6% vs. 26%) and recent close contact with a known mpox case (23% vs. 3.9%).  Larger proportions of case participants had a recent STI (26.2% vs. 13%).  Among 917 participants included in the VE analysis, 22.5% were fully vaccinated, 32.2% were partially vaccinated, and 45.4% were unvaccinated.  After adjustment, VE was 75.2% for partial vs. 85.9% for full vaccination.  Among partially vaccinated participants, VE (by administration route) was 77% for subcutaneous vs. 80.6% for intradermal.  Among fully vaccinated participants, VE was 88.9% for subcutaneous, 80.3% for intradermal, and 86.9% for heterologous administration.  Among participants with an immunocompromising condition, VE was 51% for partial vs. 70.2% for full vaccination (among people without an immunocompromising condition, rates were 72.1% vs. 87.8%).

Author’s Commentary:

In addition to providing evidence which supports the use of JYNNEOS vaccine as an effective mpox prevention intervention, this real-world analysis sheds light onto vaccine effectiveness rates by different routes of administration and also describes effectiveness rates among immunocompromised and non-immunocompromised populations.  Although more data are needed to formulate precise estimates, and the self-report survey methodology utilized in this study may have introduced bias, this study’s findings may be useful for providers and patients seeking information to help with vaccination decision-making given recent alerts regarding ongoing community transmission in the United States.

The author has no conflicts of interest to disclose.

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