Top 5 Takeaways

  1. Monkeypox Incidence: Among males aged 18–49 years eligible for JYNNEOS vaccination in the U.S., the incidence of monkeypox was 14 times higher among unvaccinated individuals compared to those who had received their first vaccine dose at least 14 days earlier.
  2. Vaccination Protection: The study suggests that a single dose of JYNNEOS vaccine provides some degree of protection against monkeypox, though the extent and duration of this protection remain unknown.
  3. Vaccination Strategy: The majority of JYNNEOS vaccinations were administered as post-exposure prophylaxis (PEP) or expanded PEP, following the FDA’s emergency use authorization for intradermal administration to increase vaccine supply.
  4. Vaccination Data Analysis: The study analyzed 5,402 monkeypox cases among males aged 18–49 across 32 U.S. jurisdictions, categorizing them based on vaccination status and timing of illness onset post-vaccination.
  5. Public Health Implications: Early findings emphasize the importance of completing the 2-dose vaccination series for eligible individuals, and ongoing surveillance is needed to confirm vaccine effectiveness.


This MMWR Article was created prior to the conventional renaming of Monkeypox to its more standard and appropriate name, Mpox. To avoid confusion, Monkeypox is retained when writing this article, but all future works should use Mpox.

Original Article Author and Citation

Corresponding Author

Amanda B. Payne,

Suggested Citation

Payne AB, Ray LC, Kugeler KJ, et al. Incidence of Monkeypox Among Unvaccinated Persons Compared with Persons Receiving ≥1 JYNNEOS Vaccine Dose — 32 U.S. Jurisdictions, July 31–September 3, 2022. MMWR Morb Mortal Wkly Rep 2022;71:1278–1282. DOI:


The study focuses on the incidence of monkeypox among unvaccinated persons versus those who received at least one dose of the JYNNEOS vaccine during the outbreak in 32 U.S. jurisdictions. The analysis showed a significantly higher incidence rate in unvaccinated males aged 18-49 compared to those vaccinated. The study underlines that while initial findings suggest protection from a single dose, the full degree of effectiveness, especially post-second dose, remains to be determined.


The study involved analyzing monkeypox cases from July 31 to September 3, 2022, categorizing them based on vaccination status and timing of illness onset relative to vaccination. Vaccination coverage and incidence were calculated, and sensitivity analyses were conducted to adjust for potential biases in vaccination status determination and population estimates.


The findings provide an early indication of the potential effectiveness of the JYNNEOS vaccine in real-world settings. The study’s limitations include potential misclassifications in vaccination status, inability to control for risk factors or behaviors influencing MPXV exposure, and the focus on a specific demographic (males aged 18–49 years). Additionally, the study couldn’t assess the effectiveness post the second dose due to limited data.


This study offers preliminary evidence suggesting that a single dose of JYNNEOS vaccine may provide some level of protection against monkeypox. However, further studies are needed to confirm these findings and assess the durability and full extent of protection, especially after the complete 2-dose series. Public health strategies should continue to focus on vaccinating high-risk populations while also promoting harm reduction strategies.


This has been your booster shot of MMWR Info! Please check back for more MMWR, Public Health, and Programming Tutorial content daily.

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes:

<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>