Mpox Update 2024

Background and what is new

The viral infection mpox caused an international outbreak(Link is external) in 2022, with over 32,000 cases in the U.S. Most cases were sexually transmitted and reported in men who self-identify as gay or bisexual. However, people of any sexual orientation, gender identity, race/ethnicity, or age can become infected and transmit mpox if exposed.

The 2022 U.S. outbreak and cases since have been due to the Clade IIb strain of the mpox virus. However, Clade I, a distinct strain of the virus which can also be sexually transmitted(Link is external), is currently causing a devastating outbreak(Link is external) in the Democratic Republic of Congo, where over 19,000 cases have been reported.

• Clade I mpox causes more severe illness and may lead to death in 5-7% of those infected.
• Cases of Clade I have not yet been reported in the U.S., but experts are concerned that international spread is possible.

Since the 2022 outbreak, cases in the U.S. have declined dramatically due to community activation, behavior change(Link is external), and uptake of the mpox vaccine by those at risk. While not at their 2022 peak, cases now are more than double what they were last year at this time, suggesting that ongoing action and vigilance is needed.

How is mpox spread and what are the symptoms?

Mpox is most often transmitted through close contact with the mpox rash(Link is external), which can look like blisters or pimples, is often painful or itchy, and may be located anywhere on the body. Secretions (like saliva) and contact with contaminated objects may also spread mpox. In areas where mpox is naturally found (e.g. Africa), it can also spread from animals to people.

• Skin lesions are infectious to others until the rash is fully healed.
• Most cases will resolve without treatment in 2-4 weeks. People with HIV or otherwise weakened immune systems are at risk for more severe infections.
• While there is no proven treatment for mpox, an experimental drug(Link is external) is available for those with severe illness or at risk of severe illness.

What you can do: be aware and consider vaccine

If you have a suspicious rash, or have had contact with someone diagnosed with mpox, you should call your healthcare provider to arrange for testing. Avoid sexual or other close skin-to-skin contact or sharing personal items with others until fully evaluated.

The mpox vaccine is available and effective.

Called Jynneos, this 2-dose vaccine is recommended for those at increased risk(Link is external) of exposure to mpox, and for those who have been exposed to mpox in the past 2 weeks. The vaccine is not recommended for everyone. Two doses are required for optimal protection.

• To date, the vaccine has been shown to be 60-90% effective(Link is external) at preventing mpox or reducing the risk of severe disease and hospitalization in those who may become infected.
• There are no current recommendations for a booster if you have been fully vaccinated, though that could change with ongoing research. People who have been vaccinated should continue to take precautions to prevent exposure.
• Jynneos was previously in short supply but is available commercially as of April 1, 2024. It is likely that it will be available through pharmacies soon.
• Members of Yale Health can self-schedule a vaccine appointment through MyChart without an order from a clinician.
   
  • Go to Menu >> Schedule an appointment >> Yale Health Center >> answer yes when asked if you are scheduling an immunization or vaccination and select mpox (Jynneos) from the list.
• People with other insurance should check with their insurance provider or contact one of the locations(Link is external) referenced by the Department of Public Health.

Certain behaviors and settings(Link is external) have been found to be associated with mpox transmission, especially raves, parties, and clubs where skin-to-skin contact may be common. Reduce your risk by staying aware of rashes on yourself and others and practicing safer sex(Link is external).

Mpox may be with us to stay, but we have the tools to keep it at bay.

Yours in health,

Madeline Wilson, MD
Chief Campus Health Officer