Severe Mpox Strain Detected in NYC

The New York City Health Department (NYCDH) recently confirmed the city's first known case of mpox clade I, a more severe strain of the sexually transmitted virus.

This case, announced by NYCDH on March 13, 2026, involves an individual who recently traveled to Europe. Officials have emphasized that this infection is travel-related, with no evidence of local transmission in New York City or its five boroughs.

The affected person has developed symptoms, sought medical care, and is currently isolating until their symptoms resolve completely.

Currently, NYCDH has not publicly disclosed the specific borough, neighborhood, ZIP code, or any other precise location within NYC for this mpox case.

"There is no known local transmission of mpox clade I in New York City, and the risk remains low for New Yorkers," stated NYC Health Commissioner Dr. Alister F. Martin.

As of today, there have been twelve clade I mpox diagnoses reported in the United States.

Clade I mpox, which is associated with ongoing outbreaks in parts of Africa, can cause more severe illness than the clade II strain responsible for the global outbreak that began in May 2022. Symptoms typically include a painful rash, fever, chills, swollen lymph nodes, and muscle aches.

The virus spreads primarily through close or intimate contact, including sexual contact.

NYCDH stressed that while the public risk is low, vaccination remains a key preventive tool, especially amid international travel.

NYC officials and the U.S. CDC continue to recommend Bavarian Nordic's JYNNEOS® (MVA-BN®) vaccination for at-risk groups.

A meta-analysis of 16 studies published in 2024 revealed that the vaccine efficacy (VE) for a single preexposure prophylactic JYNNEOS dose ranged from 35% to 86%, and the VE for two doses ranged from 66% to 90%.