Top 5 Takeaways

  1. First US case confirmed in Massachusetts: On May 17, 2022, Massachusetts reported the first confirmed case of the West African clade of Monkeypox virus via PCR testing, initiating a CDC emergency response.
  2. Spread across nine states and beyond: As of May 31, 17 cases were reported in the US across nine states, with the outbreak extending to 28 countries without endemic monkeypox, indicating person-to-person community transmission.
  3. Disproportionate impact on MSM: Most US cases (16 out of 17) were diagnosed in men who identify as gay, bisexual, or MSM, suggesting the importance of vigilant health monitoring and community awareness in these groups.
  4. Public health response and recommendations: The CDC’s rapid mobilization included health advisories, guidance for testing, public communication, and distribution of vaccines and antivirals for post-exposure prophylaxis.
  5. Importance of clinical vigilance and prevention measures: CDC emphasizes the need for health departments, clinicians, and the public to stay alert, implement infection control measures, and report suspected cases to prevent further spread.


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

Faisal S. Minhaj,

Suggested Citation

Minhaj FS, Ogale YP, Whitehill F, et al. Monkeypox Outbreak — Nine States, May 2022. MMWR Morb Mortal Wkly Rep 2022;71:764–769. DOI:


This report outlines the initial identification, spread, and public health response to the monkeypox outbreak in nine US states as of May 2022. It underscores the need for vigilance among health departments, clinicians, and the public to control the outbreak through appropriate prevention and reporting measures.


The CDC conducted a coordinated response including laboratory testing, public health advisories, clinical and testing guidance, health communication, and distribution of medical countermeasures. Investigation involved identifying cases, contact tracing, and genetic sequencing to understand transmission dynamics.


The outbreak’s identification in countries without endemic monkeypox, particularly among MSM, suggests a new pattern of person-to-person spread. Public health efforts are focused on identifying cases, preventing spread through vaccine distribution, and educating on preventive measures.


The current monkeypox outbreak requires a concerted public health effort to identify cases, trace contacts, and implement preventive measures. Vigilance among health care providers and the public, especially within high-risk groups, is crucial to controlling the outbreak.

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