California Faces New Mpox Threat: Clade I Emerges
Health authorities in California have reported three instances of mpox caused by clade I, a more virulent strain, marking the first documented local transmission of this type within the United States. These cases, occurring in individuals from Long Beach and Los Angeles County with no recent history of international travel, signal a potential shift in the mpox landscape. All three patients required hospitalization but are currently on the mend, according to the California Department of Public Health.
Mpox, a viral ailment, often presents initially with symptoms similar to influenza, such as fever, chills, and muscular discomfort. Subsequently, a distinctive rash emerges, starting as small elevated spots which evolve into fluid-filled blisters before scabbing over.
The mpox virus is categorized into two principal genetic lineages: clade I and clade II. Clade I has been responsible for widespread illness and fatalities, particularly in regions of central and eastern Africa, with the Democratic Republic of the Congo being severely impacted. Clade II was the variant responsible for the 2022 outbreak in the US and has since remained at low levels.
Seth Blumberg, from the University of California, San Francisco, emphasized the need for careful monitoring, while noting potential differences in outcomes compared to Africa.
California's Assistant State Public Health Officer, Dr. Rita Nguyen, cautioned that clade I infections could be serious and that individuals with compromised immune systems are at greatest risk for severe illness and hospitalization. She strongly advised vaccination for at-risk individuals and their sexual partners.
While anyone can contract mpox through intimate physical contact, past clade II outbreaks disproportionately affected gay and bisexual men, as well as transgender and non-binary individuals who have sex with men. California officials now suspect clade I is spreading amongst these communities.
Prior to these cases, the Centers for Disease Control and Prevention (CDC) had documented six clade I mpox infections in the US, all related to international travel. The Jynneos vaccine offers protection against both mpox clades. Full protection is achieved two weeks post the second injection, given a month after the initial dose. Booster shots are not currently advised.
While vaccination does not guarantee immunity, experts believe it reduces disease severity.
"Vaccines can prevent the severity of disease. If you were to get mpox, you would be less likely to need advanced care," said Blumberg.
The CDC is currently evaluating data and undertaking research to gain a better understanding of how the Jynneos vaccine works in the current scenario, as well as how long protection might last.
