Mpox Outbreak: US Preparedness & Global Response to Clade I Virus 2024

The World Health Organization (WHO) and the Africa Centres for Disease Control and Prevention (Africa CDC) have declared public health emergencies regarding a surge in mpox cases, specifically clade I mpox, in the Democratic Republic of the Congo (DRC) and several other African countries. This declaration, made in August 2024, underscores a growing concern about the spread of this viral disease, both within Africa and potentially beyond. While the world is still responding to the ongoing global outbreak of clade IIb mpox, this new upswing focuses on a different variant with potentially more severe characteristics. The Biden-Harris Administration has established an incident response structure to proactively prepare for potential domestic cases of clade I mpox, recognizing the distinct risks it poses compared to the clade IIb variant that has dominated recent outbreaks.

Understanding the Two Clades of Mpox

Mpox, formerly known as monkeypox, is caused by the monkeypox virus (MPXV). We find two main clades, or genetic branches, of the virus: clade I and clade II. Clade II further divides into subclades IIa and IIb. Historically, clade I has been primarily found in Central and West Africa, while clade II has been more common in West Africa. The recent global outbreak, beginning in 2022, was driven by clade IIb, largely through sexual contact among men who have sex with men. However, the current outbreak in the DRC and neighboring countries is caused by clade I, and a newer sub-clade, clade Ib, is also circulating. The emergence of clade Ib, with mutations suggesting adaptation to human-to-human transmission, is particularly concerning, as it represents the first documented sustained community spread of the virus within the DRC. The WHO notes that eleven of the 26 provinces in the DRC are considered endemic for mpox, but the geographic spread has been expanding in recent years.

Why Clade I Mpox is Different – and a Concern

Clade I mpox is raising alarms because it appears to cause more severe infections and has a higher mortality rate than clade IIb mpox. However, it’s crucial to understand that this assessment is largely based on data from the DRC, where access to comprehensive medical care is limited. As the CDC explains, the impact of clade I mpox on populations with access to advanced healthcare, like the United States, may be less severe. The current case fatality rate (CFR) in the DRC is approximately 4.9% as of May 26, 2024, with 384 deaths reported out of 7,851 cases. The clade I variant circulating in South Kivu carries genetic mutations that may affect the accuracy of diagnostic tests currently used in the DRC, potentially complicating surveillance efforts.

U.S. Preparedness and Response

Despite the current low risk to most Americans, the U.S. Government is taking a proactive approach to prepare for potential cases of clade I mpox. An incident response structure was established in February 2024, coordinating efforts across federal departments and agencies. Key components of this preparedness include:

• Enhanced Surveillance: The U.S. Is increasing its capacity to detect both clade I and clade IIb mpox through existing surveillance systems, including wastewater testing, and expanding diagnostic testing capabilities.
• Vaccine Availability: Over one million vials of the JYNNEOS mpox vaccine have been distributed across the United States since August 2022, initially to combat the clade IIb outbreak. This vaccine is expected to offer some protection against clade I mpox, particularly for those already vaccinated against clade IIb. The CDC provides eligibility information on its website.
• Treatment Options: The U.S. Government is working to understand the effectiveness of existing mpox treatments and ensure availability should clade I cases emerge domestically.
• Public Health Guidance: The CDC has issued updated Health Alert Network advisories for clinicians and public health departments, as well as updated Travel Health Notices recommending enhanced precautions for travelers to the DRC and neighboring countries.

Global Support and Financial Assistance

The United States is providing significant financial and technical support to the mpox response in Africa. In fiscal year 2023, the U.S. Allocated over $2.65 billion in bilateral health funding to Central and Eastern African countries. Since March 2024, USAID and the CDC have jointly provided $20 million USD to support clade I mpox response efforts, and an additional $35 million has been announced, pending Congressional Notification, bringing the total proposed U.S. Government financial support to over $55 million. This support focuses on critical public health interventions, including surveillance, risk communication, laboratory diagnostics, infection prevention and control, clinical services, and vaccine planning. The U.S. Is also donating 50,000 doses of the JYNNEOS vaccine to the DRC and providing financial support for its rollout. More than 200 staff, including epidemiologists, laboratorians, and risk communication experts, have been deployed to support response efforts both in the U.S. And in Africa.

Travel Considerations

Currently, the CDC and WHO do not discourage travel to the DRC or neighboring countries due to the mpox outbreaks. However, travelers are advised to practice enhanced precautions, including avoiding close contact with individuals exhibiting symptoms of mpox (rash, fever, swollen lymph nodes) and practicing good hygiene. The State Department is working to keep U.S. Citizens abroad informed of the latest updates and recommendations.

Looking Ahead: Continued Vigilance and Collaboration

The U.S. Government emphasizes a whole-of-government response, building on lessons learned from the 2022 mpox outbreak. Ongoing efforts include continued surveillance, research into the effectiveness of existing treatments, and collaboration with international partners, including the WHO and Africa CDC. The situation remains dynamic, and public health guidance may evolve as new information becomes available. For the most up-to-date information on mpox, including signs and symptoms, prevention, and treatment, please visit the CDC website. The U.S. Will continue to monitor the spread of clade I mpox, support affected countries, and prepare for potential domestic cases to safeguard public health.