Ireland’s First Mpox Clade 1b Outbreak Confirmed in 2025

A recent Eurosurveillance rapid communication details Ireland's first known outbreak of the monkeypox virus (MPXV) clade 1b, involving four linked cases from August to October 2025, with cases related to a Dublin hospital.

On December 18, 2025, in Volume 30, Issue 50, the researchers wrote that, to the best of our knowledge, the first reported nosocomial transmission of MPXV clade Ib outside Africa occurred alongside the ongoing rise in MPXV clade Ib importations in countries outside Middle Africa.

This cluster highlights the ongoing possibility of mpox transmission from travel-associated cases. It emphasises the need for a high level of clinical suspicion for mpox in cases with relevant clinical symptoms and travel to countries where mpox is currently circulating.

The Irish outbreak originated with a traveler returning from Pakistan and spread via sexual, household, and nosocomial (in a healthcare setting) transmission. The cases were genetically identical and related to a sequence from Oman in February 2025.

The close relationship between the Oman and Irish sequences highlights the role of international travel in the spread of clade 1b and the potential for global transmission, the researchers added.

Since the second declaration of a public health emergency of international concern for mpox was lifted in September 2025, both MPXV clades I and II, and their subclades, continue to circulate globally, the World Health Organization (WHO) Disease Outbreak News reported in early December 2025.

The WHO considers there to be community transmission of the Mpox virus in various European countries, such as Belgium, Germany, and Spain.

In Ireland, as of December 21, 2025, the MVA-BN (JYNNEOS) vaccine is authorized in response to mpox outbreaks.

And when departing for Ireland or other mpox-risk countries, the U.S. CDC recommends international travelers speak with a travel vaccine advisor regarding immunization options.