Mpox Outbreak

Mpox Outbreaks 2024

The World Health Organization (WHO) says mpox outbreaks linked to clade II began in 2017 and continues in 2024. The WHO's Global Strategic Preparedness and Response Plan for mpox, covering the six months from September 2024 to February 2025, was announced on August 26, 2024. The WHO Director-General declared a public health emergency of international concern (PHEIC) regarding mpox clade II outbreaks on July 23, 2022. The WHO announced the PHEIC ended on May 11, 2023. On August 14, 2024, the WHO Director-General determined that the upsurge of mpox clade 1 virus cases in the Democratic Republic of the Congo and a growing number of African countries constitutes a new PHEIC. The WHO published updated mpox FAQs on August 17, 2024. The WHO's Mpox External Situation Report #33 confirmed that it had received mpox case reports from 117 affected countries since May 2022. The WHO released a new framework for Enhancing Prevention and Control of mpox- 2024-2027 on May 24, 2024, for preventing and controlling future mpox outbreaks.

Mpox Virus Clades

According to the WHO, the natural reservoir of the zoonotic mpox virus (MPXV) remains unknown. There are two MPXV clades: clade I, previously known as the Congo Basin clade, and clade II, formerly the West African clade; clade II further has two subclades: clade IIa and clade IIb. A February 2023 study demonstrated that the clades exhibit highly significant differences in CAST/EiJ mice in the order clade I > clade IIa > clade IIb, similar to the severity of clinical disease in humans. Clade I outbreaks are deadlier (10%) than clade II outbreaks, says the WHO. 

In May 2022, an outbreak of clade IIb MPXV was detected in the Canary Islands. Clade I MPXV community outbreaks occur regularly in Africa, in countries such as Cameroon, the Central African Republic, and the Democratic Republic of Congo (DRC). In 2024, the DRC reports a significant surge of mpox Clade 1 cases ever recorded. Before April 2023, no documented clade I MPXV cases were registered globally.

Mpox Outbreak United States

In the U.S., initial mpox virus clade IIb cases were detected in Boston, MA, in May 2022. The U.S. government declared an outbreak in August 2022. As of March 2024, the U.S. Centers for Disease Control and Prevention (CDC) reported 32,063 confirmed cases of mpox and 58 deaths in the U.S. On January 31, 2023, the U.S. HHS did not renew the public health emergency declaration for mpox. The mpox public health emergency in San Francisco, CA, ended on October 27, 2022, followed by New York in November 2022. 

As of June 2024, the Los Angeles County Department of Public Health reported an increasing rate of mpox cases. From October 2023 to April 30, 2024, 42 states, the District of Columbia, and Puerto Rico reported 1,802 probable and confirmed mpox cases to the CDC. In 2024, mpox cases were reported in urban centers such as New York City, which confirmed 42 mpox cases from April 7, 2024, to May 4, 2024.

The ACIP presentation on October 25, 2023, reviewed mpox infections in Chicago, indicating an increase in mpox (18), particularly among previously JYNNEOS vaccinated persons. And in a CDC Morbidity and Mortality Weekly Report published on September 1, 2023, among 38 (73%) patients with no known exposure to a person with mpox, behaviors preceding illness included sexual activity (17; 45%), close face-to-face contact (14; 37%), attending large social gatherings (11; 29%), and being in occupational settings (10; 26%). The CDC published a Dispatch, Volume 29, Number 10—October 2023, confirming that 1.3% of reported mpox instances were in children and adolescents <18 years of age. The U.S. CDC Advisory Committee on Immunization Practices (ACIP) presented various mpox data on June 23, 2023. 

Mpox Africa

The first human case of Mpox was identified in the Democratic Republic of Congo (DRC) in 1970. During 2016–2022, PCR testing confirmed 100 mpox cases among 302 suspected cases in the Central African Republic. In June 2024, the U.S. CDC issued a Level 2 Travel Health Advisory regarding the DRC's ongoing mpox outbreak. In March 2024, researchers reported 21,630 suspected MPXV Clade 1 cases and 1,003 deaths. 

Mpox Europe

The European Centre for Disease Prevention and Control (ECDC). The ECDC reported on August 16, 2024, that the likelihood of infection with MPXV clade I for EU/EEA citizens traveling to or living in the affected areas and having close contact with affected communities is high, while the likelihood of infection is low when contacts with affected communities are avoided. The severity of the disease is expected to be low. On August 15, 2024, Sweden reported one travel-related mpox clade Ib case in an African visitor.  Overall, the risk for these populations is moderate and low, respectively. The ECDC and WHO published a statement confirming that 26,703 mpox cases were identified from May 2022 to January 14, 2024, from 45 countries and areas throughout the European Region. Over the past four weeks, 138 cases of mpox have been identified from 11 countries and areas in Europe.

Mpox Pacific Region

China's National Health Commission (NHC) confirmed in a statement in September 2023 that it plans to manage mpox, Category B protocols, similar to other infectious diseases such as COVID-19, HIV, and rabies, after detecting 501 cases of viral infection in August 2023. These reported cases have been identified as clade IIb MPXV. The WHO situation report #27, published on August 14, 2023, identified sustained community transmission of mpox in China. Mpox cases increased to 491 on the Chinese mainland in July 2023, according to China's Center for Disease Control and Prevention (China CDC). That was an increase from 106 cases in June 2023. Since June 23, 2022, China has listed mpox as a second-class legal infectious disease. The WHO reported 106 mpox cases in Beijing in July 2023, plus recent infections in Taiwan and Hong Kong. The Hong Kong Special Administrative Region of the People's Republic of China recently recorded its fifth Mpox patient since September 2022. The Taiwan Centers for Disease Control and Prevention reported that 266 cases (250 local and 16 imported cases) have been diagnosed in Taiwan. As of August 7, a total of 77,809 mpox vaccination services have been completed in China.

A U.S. CDC study reported in July 2023 that asymptomatic mpox infections were likely underestimated in Japan and were comparable in magnitude to symptomatic infections. Japan's Ministry of Health, Labor and Welfare Health reported 169 mpox cases as of May 28, 2023, since the first domestic case in July 2022. On March 20, 2023, the Japanese Ministry of Health reported 13 men were confirmed to have a mpox infection. The Western Pacific Region reported additional mpox cases in early April 2023, driven by an outbreak of mpox affecting mainly men in Japan. 

The Korean Herald reported that Korea's Centers for Disease Control and Prevention announced in April 2023 that it would raise the crisis alert level from 'Level 1' to 'Level 2 caution' following a mpox outbreak of about sixty cases.

Mpox United Kingdom

The U.K. Health Services Agency (UKHSA) began reporting mpox cases in March 2022, which accelerated in May 2022. The first smallpox specimen was identified during this outbreak through retrospective testing in the United Kingdom on March 7, 2022. From 2023 to March 2024, 160 cases of mpox have been reported in the UK. Of these, 153 were in England (68 cases were presumed to have acquired mpox in the UK, 58 were acquired outside the UK, and 27 are awaiting classification). The UKHSA published that the mpox clade of monkeypox predominantly circulating in the U.K. (Clade IIb, B.1 lineage) was no longer classified as a High Consequence of Infectious Disease. Before the recent outbreak, between 2018 and 2021, there were seven cases of mpox in the U.K. Of these; four were imported cases. There was no documented community transmission in previous outbreaks.

Mpox in Women

Eurosurveillance published a study on December 1, 2022, on mpox infections in 158 women. The average age of female patients was 34 years. The most likely transmission mechanism was close contact during sexual relationships. 

Mpox Vaccines and Treatments

Various mpox vaccines (JYNNEOS®) and treatments (TPOXX) are authorized in 2024. Numerous research studies have clinically reviewed the mpox outbreak as of September 2023.