The Democratic Republic of Congo (DRC) is grappling with a deadly outbreak of mpox caused by a novel, sexually transmitted strain of the virus. This new outbreak emerged in September 2023 and is spreading. Its close proximity to DRC’s eastern borders and its spread have spurred concern among experts about another potential global health emergency.
We urge the international community to heed these calls and take swift action while we still have the opportunity to avert grave global consequences.
Several Distinct Variants
The mpox virus, formerly known as monkeypox, is a close relative to the virus that causes smallpox. Prior to 2022, mpox was recognized only as a relatively mild disease in parts of West Africa, while a more severe form of the disease was found in central DRC. This geographic difference was attributable to two genetically distinct circulating variants (or clades) of the mpox virus, clade I in DRC and clade II in West Africa.
The 2022 mpox clade IIb epidemic changed our understanding dramatically. In contrast to prior human mpox cases, clade IIb is genetically distinguishable from its clade IIa ancestor and is transmitted efficiently from person to person, primarily through sexual contact. The clade IIb strain has swept quickly across the globe and, to date, has caused nearly 96,000 documented cases and at least 184 deaths in 116 countries.
We now are faced with a more ominous mpox threat in 2024. The historically more severe Congo basin variant of virus (clade I) appears to have mutated to be more severe and maintains the ability to readily pass sexually from person to person. A recently published research manuscript characterized a large outbreak of sexually transmitted mpox that occurred in October 2023 in eastern DRC, along a major road and within 100 miles of Rwanda and Burundi. When researchers sequenced the virus, it was different enough for them to designate it as a new clade Ib. While reminiscent of 2022, the clade Ib virus appears to be significantly more lethal, with death rates estimated between 4.3% and 5.7%.
A Complex Situation
The situation in DRC is complicated and urgent. It is likely that three distinct clades of mpox virus are simultaneously infecting humans. The newest variant (clade Ib) combines the worst characteristics of the other two — efficient sexual transmission (a la clade IIb) and high mortality (a la clade I).
Unfortunately, it is quite difficult to differentiate the clades based upon individual clinical presentation. DRC lacks basic diagnostic capacity at the healthcare facility level, and the rest of the world lacks diagnostic tests that can quickly differentiate mpox clades. Clade Ib has been rapidly spreading throughout central Africa after first being reported in the DRC in September 2023. If the outbreak is allowed to grow, it is only a matter of time before clade Ib cases appear globally.
The DRC’s ability to contain this outbreak hinges on two actions: expanding its diagnostic and surveillance capacity, and acquiring and distributing vaccines. Fortunately, biodefense efforts in wealthy nations have yielded stockpiles and manufacturing capacity for smallpox vaccines, which also offer protection from mpox. The COVID-19 pandemic response demonstrated the potential for rapid scaling of diagnostics and surveillance.
International Help is Needed
Now is the time for the international community to direct these resources toward DRC and its neighbors, but efforts so far have fallen short. The U.S. Agency for International Development offer in April for 50,000 vaccine doses from the U.S. stockpile is grossly insufficient for a country of 100 million persons facing a rapidly escalating epidemic — what’s worse, the U.S. still hasn’t delivered on its promise. If DRC were to try to purchase vaccines, the $200 cost per course would be a prohibitive expense for a low-income nation.
Logistical issues have also marred the deployment of the vaccines to the DRC, further complicating response efforts. Prequalification and Emergency Use Listing of these vaccines by the WHO could facilitate the swift purchase and deployment of vaccines, yet these actions are typically lengthy and issued only during a Public Health Emergency of International Concern (PHEIC). While, the mpox outbreak has not yet been declared a PHEIC, the WHO is currently considering whether to do so. We hope it acts swiftly and decisively in this regard.
The dire situation in the eastern DRC is exacerbated by armed violence and instability. Refugee camps in these areas can be breeding grounds for the virus. The mobility of affected populations — including sex workers — in these border regions complicates containment efforts and underscores the necessity of comprehensive and immediate intervention. We propose the following recommendations for action to the international community:
Strengthen diagnostics, surveillance, and reporting. Rapidly partner with DRC and neighboring countries to expand mpox diagnostic testing, epidemiological surveillance, and reporting systems. Early recognition, clinical characterization, and clade differentiation will enable timely interventions and prevent cross-border transmission.
Accelerate vaccine access and distribution. Facilitate adequate supply and rapid deployment of vaccines to the affected regions of DRC. This includes direct donation, subsidies for purchase, and logistical support for last-mile delivery and administration. This effort includes:
- Expediting WHO Emergency Use Listing: WHO should create an expedited process to prevent further spread of the mpox and future threats.
- Establishing a global mpox vaccine stockpile: Gavi (the Vaccine Alliance) and WHO should establish a global stockpile of mpox vaccines to facilitate rapid response for regions experiencing an outbreak.
Infectious diseases do not respect national boundaries; a dangerous outbreak anywhere threatens all of us. The expanding threat of mpox clade Ib in the DRC is a stark reminder of our collective vulnerability. The international community must recognize the modern reality of global interconnectedness and act decisively. This means supporting the rapid deployment of vaccines, diagnostics, and antiviral treatments to regions in need. It also means establishing a global stockpile of mpox vaccines, as Gavi and the WHO have proposed, and creating a rapid response mechanism for future outbreaks.
The lessons of the COVID-19 pandemic should not be forgotten so quickly. Delayed responses and inequitable access to vaccines and treatments led to needless suffering, loss of life, and global disruption. We cannot afford to repeat these mistakes. If we act boldly now, perhaps we can avoid a repeat of history and prevent the current outbreak from becoming a pandemic.
Syra Madad, DHSc, MSc, MCP, is Chief Biopreparedness Officer of NYC Health + Hospitals. Robert Glatter, MD, is assistant professor of emergency medicine at the Zucker School of Medicine at Hofstra/Northwell, Lenox Hill Hospital, and Northwell Health. James Lawler, MD, MPH, is a professor in the Division of Infectious Diseases, and director of International Programs and Innovation in the Global Center for Health Security at the University of Nebraska.
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