New strain of mpox virus: What you need to know
December 9, 2025
The United Kingdom’s confirmation of a recombinant mpox virus underscores the ongoing evolution of this pathogen and the need for sustained global vigilance. The hybrid strain, formed from Clades Ib and IIb, emerged in a traveler returning from Asia and highlights how recombination can occur when multiple virus types circulate simultaneously. Experts stress that while this new variant poses no immediate heightened threat, continuous monitoring, vaccination, and laboratory analysis are critical to assess potential changes in transmissibility or virulence. The case serves as a reminder that mpox remains a dynamic global health concern requiring international cooperation and robust surveillance.
The detection of a recombinant mpox strain in the United Kingdom marks an important moment in the ongoing evolution of the virus. Identified in a traveler returning from Asia, the hybrid strain combines genetic material from Clades Ib and IIb, which have been responsible for outbreaks in both Africa and Asia. This genetic recombination, a natural process that occurs when two versions of a virus infect a host simultaneously, reflects the adaptability of mpox and the continuing risks of global transmission.
Experts from the UK Health Security Agency (UKHSA) and academic institutions, including Oxford University’s Pandemic Sciences Institute, emphasize that there is no evidence this recombinant variant is more contagious or virulent than existing strains. However, its emergence underscores how mpox continues to evolve in areas where viral circulation remains high and vaccination coverage remains uneven. Researchers are calling for further laboratory and epidemiological studies to determine whether the hybrid virus differs in its ability to spread or cause disease.
Globally, mpox remains endemic in parts of Africa and has seen sporadic reemergence in Asia, Europe, and the Americas since the 2022 global outbreak. The World Health Organization downgraded mpox from a public health emergency in late 2025, but sustained transmission in regions such as the Democratic Republic of the Congo demonstrates that the virus remains a serious concern.
The case also underscores the importance of maintaining vaccination programs and preventive measures. The JYNNEOS vaccine continues to offer strong protection against Clade II viruses, but limited access in some regions increases the risk of further viral recombination. The lesson from the UK’s recombinant mpox case is clear: persistent surveillance, equitable vaccine distribution, and rapid global data sharing remain essential to containing an evolving virus that is unlikely to disappear soon.