Monkeypox disease, now commonly referred to as mpox, was once considered a geographically restricted zoonotic disease but has emerged as a global public health concern. The 2022 multinational outbreak marked a turning point, with notable shifts in transmission dynamics, affected populations, and clinical manifestations. Classical cases typically involve fever, lymphadenopathy, and a centrifugal vesiculopustular rash; however, recent outbreaks have revealed atypical presentations, including genital and perianal lesions, minimal or absent prodromal symptoms, and asynchronous rash evolution. These variations have complicated early clinical recognition and may contribute to delayed diagnosis and onward transmission. This review synthesizes current evidence on the evolving epidemiology of mpox, highlights differences between endemic and non-endemic outbreaks, and describes the full spectrum of typical and atypical clinical features. It also assesses diagnostic approaches, including molecular and point-of-care techniques, and evaluates the efficacy and limitations of current and emerging vaccines, such as JYNNEOS and ACAM2000. Future priorities include improving global surveillance, refining case definitions, expanding diagnostic access, and ensuring equitable vaccine distribution. Understanding the expanding clinical and epidemiological profile of mpox is essential for timely diagnosis, containment, and preparedness against future outbreaks.

Objectives
With the recent global mpox outbreak, the JYNNEOS vaccine (Modified Vaccinia Ankara-Bavarian Nordic) was developed as a third-generation smallpox vaccine and initially favored for mpox immunization. Vaccine-associated side effects contribute to vaccine hesitancy. Consequently, tracking adverse events post-immunization is crucial for safety management. This study used data from the national active vaccine safety surveillance conducted in Korea from August 25 to November 24, 2022 to detect potential safety signals and adverse events. Methods: Data on health conditions following vaccination were gathered from web-based surveys and reported via active surveillance through the Immunization Registry Information System. This follow-up system functioned via a text message link, surveying adverse events and health conditions beginning on the second day post-vaccination. Information about specific adverse events, including both local and systemic reactions, was collected. Results: The study included 86 healthcare workers who had received at least 1 dose of the JYNNEOS vaccine. Among the respondents, 79.1% reported experiencing at least 1 adverse event, with the majority being local reactions at the injection site. The incidence of adverse events was higher following the first dose (67.9%) than after the second dose (34.4%). The most frequently reported adverse event for both doses was mild pain at the injection site. Conclusion: The study provides crucial information on the safety of the JYNNEOS vaccine, demonstrating that most adverse events were manageable and predominantly localized to the injection site. Nonetheless, additional research is needed on the safety of various vaccine administration techniques and the vaccine’s effects on broader demographics.