San Francisco Department of Public Health Confirms First Clade I Mpox Case in San Francisco

SAN FRANCISCO – On April 14, the San Francisco Department of Public Health (SFDPH) confirmed the first case of clade I mpox in a San Francisco resident. The case occurred in an unvaccinated adult who was hospitalized and is improving. The individual reported close contact with someone who traveled internationally. 

SFDPH strongly encourages people at risk for mpox to receive both doses of the mpox vaccine. The vaccine provides the best protection against the mpox virus and protects against both clade I and clade II. At this time, mpox exposure risk is low for individuals who are not in higher‑risk groups.  

The mpox vaccine is available through healthcare providers and local pharmacies. Those who do not have insurance or are having difficulty accessing care may visit the locations listed at sf.gov/mpox. 

About Mpox

There are two types of mpox, clade I and clade II. The 2022 outbreak in the United States and California was caused by clade II mpox. In the United States, both types are spread primarily through close skin-to-skin contact, including during sexual activity.  

Both clade I and clade II mpox cause similar symptoms, which may start with flu-like symptoms such as a fever, swollen lymph nodes or fatigue, followed by a rash that looks like pimples or blisters. People who have a rash that looks like mpox should contact their healthcare provider to get tested and talk to their partners so they can take steps to prevent the spread of infection. 

While anyone can get mpox, most reported cases in the United States are among gay, bisexual, and other men who have sex with men, as well as transgender persons who have sex with men.  

Reported cases of clade I mpox in the United States remain rare. Public health officials are monitoring cases to determine if clade I mpox is more severe than clade II mpox in this country.  

“SFDPH is closely monitoring mpox. While clade I mpox cases remain rare in the United States, clade II mpox cases continue to occur in San Francisco and throughout California,” said San Francisco Health Officer Dr. Susan Philip. “This development reminds us just how important it is to be fully vaccinated against mpox if you are at risk. With summer travel and events quickly approaching, now is a great time to seek the mpox vaccine.” 

Mpox Vaccine

SFDPH strongly encourages people at risk for mpox to receive both doses of the mpox vaccine. This includes people at risk who plan on traveling to places where clade I mpox has been reported, including Europe and Africa.  

The mpox vaccine remains the best protection against both clade I and clade II mpox. It significantly reduces the chance of infection, and it helps prevent severe illness, hospitalization, and death among people diagnosed with mpox. The mpox vaccine is safe for people who are immunocompromised, including people living with HIV and people taking immune suppressing medications. 

People can receive their second dose of the mpox vaccine if it has been at least 28 days since their first dose. There is no need to restart the two-dose series if it has been over 28 days since the first dose. Booster doses are not recommended at this time for people who have completed the two-dose series. In addition, mpox vaccination is not currently recommended for people who have previously been infected.  

No vaccine is 100% effective, and people who are fully vaccinated against mpox should still be aware of mpox symptoms and get tested if they have them.  

In addition to getting vaccinated, condom use and reducing the number of sexual partners can further decrease the risk of mpox infection.