Explosive mpox outbreak in Sierra Leone overwhelms health systems
June 2, 2025
Sierra Leone’s explosive mpox outbreak, now accounting for three-quarters of all new African cases, underscores an urgent need for expanded vaccine access and global attention. With limited bed capacity and only 61,000 vaccine doses received so far, the country is ill-equipped to manage a fast-spreading crisis. Scientists are puzzled by Clade IIb’s behavior, which mimics the more severe Clade Ib strain in transmission and symptoms. While sexual contact appears to be the primary driver, concerns linger about other transmission modes. Immediate vaccine deployment and international support are essential to avert regional spillover and prevent a broader global resurgence.
Sierra Leone is facing a staggering mpox outbreak, with over 3,000 confirmed cases and its capital, Freetown, at the epicenter. The virus, identified as Clade IIb, is spreading with unprecedented speed and severity, raising alarms across the public health community. What’s perplexing is that although Clade IIb has previously shown slower sexual transmission among men who have sex with men, in Sierra Leone the virus appears to be spreading rapidly among both men and women, with many patients showing full-body lesions—a clinical presentation more consistent with the more virulent Clade Ib strain.
This unusual presentation has confounded researchers, prompting the Africa CDC and WHO to deploy investigative teams to the country. Scientists now suspect that under the right local conditions—such as limited access to care, high HIV prevalence, or delayed diagnoses—Clade IIb may behave much like Clade Ib. If so, the current classification system may require revision, and surveillance strategies must adapt accordingly.
Despite the growing crisis, vaccine availability remains staggeringly low. Of the 1.3 million mpox vaccine doses shipped to Africa, Sierra Leone has received only 61,000, with another 50,000 recently allocated. Experts stress this is grossly insufficient, especially given that effective contact tracing would ideally vaccinate about 200 people per confirmed case.
As new cases spill into neighboring Liberia and risk broader regional spread, global health agencies must urgently ramp up vaccine donations, surveillance, and support. What is unfolding in Sierra Leone is not only a public health emergency but a critical opportunity to address gaps in global outbreak preparedness. The time to act decisively is now—before this localized epidemic becomes a regional or global catastrophe.