First Case of Clade I Mpox Detected in Novel York City

New York City health officials have confirmed the first case of Clade I mpox in a resident who recently traveled internationally. While the risk to the general population remains low, the detection of this variant prompts increased vigilance and reinforces the importance of vaccination for those at higher risk.

Understanding Mpox Clades

The mpox virus has two main clades: Clade I and Clade II. The 2022 global outbreak was caused by Clade II. Clade I mpox is currently responsible for an outbreak in Central and Eastern Africa, which began in 2024 [1]. The World Health Organization (WHO) declared a public health emergency of international concern over the spread of Clade I in August 2024 [2].

Clade I mpox has historically been associated with more severe disease than Clade II [1], though cases exported outside of Africa have generally been less severe. Both clades spread through similar modes of transmission and can be prevented using the same methods.

Current Situation in New York City and the U.S.

As of March 12, 2026, 45 people in New York City have tested positive for mpox, with 16 cases reported in the last month (February 8 to March 7, 2026) [1]. Yet, these cases are Clade II. The recently identified case is the first confirmed instance of Clade I mpox in the city [3].

Nationwide, there have been 11 reported cases of Clade I mpox since November 2024, primarily among individuals with recent travel history to affected areas in Central and Eastern Africa [4]. Three cases reported in October 2025 had no recent travel history and genomic data linked them to a previous travel-related case from August 2025 [4].

Transmission and Prevention

Mpox spreads through close, intimate contact, including oral, anal, and vaginal sex, hugging, kissing, biting, cuddling, and massaging [1]. In the U.S., transmission has primarily occurred within social networks of gay men and other men who have sex with men, and transgender people, but anyone in close contact with an infected individual is at risk.

Prevention measures include:

• Vaccination with the JYNNEOS vaccine (recommended for those at high risk)
• Avoiding close, intimate contact with individuals who have symptoms
• Practicing good hygiene

Who Should Receive Vaccinated?

The New York City Department of Health recommends vaccination for:

• Men who have sex with men, including transgender, non-binary, gender fluid, or gender non-conforming individuals
• People planning to travel to regions where Clade I mpox is circulating and anticipate sexual encounters with new partners
• Individuals who consider themselves at risk of exposure through sexual or intimate contact

Those who have already had mpox do not require to be vaccinated at this time.

What to Do If You Have Symptoms

If you develop a new or unexpected rash or sores, contact a healthcare provider immediately. Be sure to inform them about any recent travel history [1].

Accessing Vaccination

New York City residents can access vaccination through the city’s health map or by contacting 311 for information on authorized centers and appointment availability.