āKey Messaāges
On November 15, 2024, testing at the California Department of Public Health (CDPH) confirmed the first case of mpox infection from clade I monkeypox virus (MPXV) in the United Statesāā. The patient recently traveled from an affected country, where clade I MPXV is actively spreading. The patient has relatively mild illness and is recovering after seeking medical care for mpox symptoms.
CDPH and the CDC have been preparing for prompt detection and response to potential clade I cases as clade I MPXV has historically been more transmissible and caused more severe disease than clade II MPXV. However, recent outbreaks have reported death rates as low as 1% when patients received good medical oversight and suāāpportive clinical care.
- āāāāāāFoāllowāÆspecimen collection guidelines. Use full PPE and 2 sterile synthetic swabs to vigorously swab and collect specimens from ~2-3 lesions. Do not de-rāoof or aspirate lesion(s) due to risk of sharps injury and exposure.
If clāade I mpox infection is suspected, patients should be advised to isolate and providers should notify their local health department immediately and work with them to send specimens for expedited clade-specific mpox testing, which is available at the CDPH Viral and Rickettsial Disease Laboratory (VRDL).
Medicaāāl countermeasures used in the ongoing clade IIb global outbreak, including the mpox vaccine, are anticipated to be effective for clade I MPXV.
Iān Augāāāust 2024, initial results from a study in the Democratic Republic of the Congo showed that tecovirimat (TPOXX) was safe but did not improve clade I mpox resolution. Additional data analyses are underway to better understand the results of this study, including if there was any benefit to a subset of people who received TPOXX. Providers should contact their local health department to access medication for any patients who have severe manifestations or are immunocompromised. Inform patients with mpox about the STOMP trial (STOMP Trial, call 1-855-876-9997) and recommend that they enroll. Oral TPOXX is available through the STOMP trial.
Providers and LHDs should continue to encourage vaccination for patients who may be at risk for mpox. Vaccination is particularly important for people with weakened immune systems related to HIV infection or other conditions as they are at risk for severe disease. Vaccination coverage in āCalifornia remains low, with less than half of people who are eligible to receive the vaccine having received both doses of JYNNEOS vaccine.
- JYNNEOS may also be given as post-exposure prophylaxis to asymptomatic persons ideally within 4 days but up to 14 days after exposure if they have not already received two doses of vaccine or bāeen previously infected with mpox.