New Mpox Strain Detected: WHO Calls for Monitoring | UK & India
- Health officials are closely monitoring a newly identified recombinant strain of mpox, a virus previously known as monkeypox, detected in both the United Kingdom and India.
- This new strain is described as a recombinant virus, meaning it contains genetic material from two previously known clades, or branches, of the monkeypox virus: Ib and IIb.
- The first case was identified in December 2025 in the United Kingdom in a traveler returning from a country in the Asia Pacific region.
Health officials are closely monitoring a newly identified recombinant strain of mpox, a virus previously known as monkeypox, detected in both the United Kingdom and India. The World Health Organization (WHO) confirmed the cases on , emphasizing the continued need for genomic surveillance, though the overall global public health risk assessment remains unchanged.
Understanding the New Strain
This new strain is described as a recombinant virus, meaning it contains genetic material from two previously known clades, or branches, of the monkeypox virus: Ib and IIb. Recombination is a natural process that occurs when two related viruses infect the same individual and exchange genetic material, resulting in a new variant. According to the WHO, the two identified individuals, who experienced mild illness, fell ill several weeks apart but with the same recombinant strain, suggesting the possibility of additional undetected cases.
The first case was identified in December in the United Kingdom in a traveler returning from a country in the Asia Pacific region. Initial testing identified the virus as clade Ib, but subsequent whole genome sequencing revealed the presence of genetic regions from both clade Ib and clade IIb.
Mpox: A Review of the Virus and its Spread
Mpox is an infectious disease caused by the monkeypox virus (MPXV), which belongs to the Orthopoxvirus genus – the same genus as the virus that causes smallpox. The virus spreads through close physical contact, including sexual contact, and can also be transmitted through contact with contaminated materials or, less commonly, through respiratory droplets.
Typical symptoms of mpox include fever, swollen lymph nodes, and a characteristic rash or lesions. While many infections are mild, the virus can cause more severe illness in certain individuals.
Previous Outbreaks and Vaccination Efforts
Clade IIb is linked to a global mpox outbreak in that affected numerous countries worldwide. More recently, clade Ib has shown early signs of local spread in some European countries, prompting health officials to encourage vaccination among those at higher risk.
In the UK, vaccination is currently available for groups considered to be at the highest risk of contracting mpox, including individuals who have multiple sexual partners, engage in group sex, or frequent sex-on-premises venues. The vaccine is reported to be 75-80% effective in preventing severe disease.
What is Known About Vaccine Effectiveness Against the New Strain?
Currently, there have been no specific studies evaluating the effectiveness of the existing vaccine against this newly identified recombinant strain. However, health officials believe there will likely be a high degree of protection. Dr. Katy Sinka, head of sexually transmitted infections at the UK Health Security Agency (UKHSA), stated that genomic testing allowed for the detection of the new strain and emphasized that viruses naturally evolve. She reiterated the importance of vaccination as a proven method to protect against severe illness.
The Importance of Genomic Surveillance
The detection of this recombinant strain underscores the critical role of ongoing genomic surveillance in monitoring the evolution of mpox. By analyzing the genetic makeup of the virus, public health officials can identify new variants, track their spread, and assess their potential impact on vaccine effectiveness and disease severity.
The WHO’s statement highlights that continued monitoring is essential, even though the current global public health risk assessment remains unchanged. This proactive approach allows for a rapid response should the new strain exhibit characteristics that warrant increased concern.
What Should the Public Do?
While the WHO currently assesses the global risk as unchanged, individuals should remain vigilant and practice preventative measures. These include avoiding close physical contact with individuals exhibiting symptoms of mpox, practicing good hygiene, and considering vaccination if eligible. Those with recent travel histories, particularly from regions where mpox is circulating, should be aware of the symptoms and seek medical attention if they develop.
Further analysis of the virus is underway to better understand its characteristics and potential implications. Public health agencies will continue to provide updates as more information becomes available.