New Mpox Strain Detected: What the Recombinant Virus Means for the Future
Public health officials in England have identified a new combined type of mpox in a person who recently traveled to Asia. The virus is a unique mix of the two known types of mpox, raising concerns about future spread and the virus’s ability to evolve.
Understanding Mpox and Its Types
Mpox, formerly known as monkeypox, is related to the smallpox virus. Initial symptoms typically include fever, headache, muscle aches, and backache, often followed by swollen lymph nodes and exhaustion. A rash or sores then appears, usually starting on the face and spreading to other parts of the body. The virus can spread through contact with these sores, fluids from the sores, or through saliva and respiratory secretions.
Currently, two main types of the virus are circulating globally: Clade IIb and Clade Ib.
Clade IIb: The 2022 Outbreak Strain
Clade IIb was responsible for the global mpox outbreak in 2022, infecting approximately 114,000 people and causing 220 deaths worldwide. The United States saw a peak of 11,000 cases per month during that summer. This strain is generally considered less severe, causing mild symptoms and having a mortality rate of around 1%.
Clade Ib: A More Serious Threat
Clade Ib causes more serious illness, with a fatality rate around 10%. Historically found in the Democratic Republic of Congo (DRC), transmission was primarily from animals to humans. Though, a recent outbreak in the DRC, beginning in 2023, shows person-to-person spread, including transmission within families and healthcare settings where protective gear is limited. Cases have been reported in children under 15, and in some areas, sexual transmission is becoming more common, including heterosexual transmission among sex workers and transient workers.
Between January and November 2025, over 48,000 cases of Clade Ib mpox were reported in Central and Eastern Africa, with about 43 cases reported in other countries. Roughly half of these cases involved recent travel to Africa, but 24 occurred in individuals with no travel history.
The World Health Organization (WHO) believes Clade Ib mpox is now spreading locally in Italy, Malaysia, the Netherlands, Portugal, Spain, and the United States.
The New Recombinant Strain: A Cause for Concern?
Genomic testing revealed the case in England involves a recombinant virus – a combination of genetic material from both Clade IIb and Clade Ib. Experts note that viral evolution is normal, especially with both types currently circulating. However, this recombination raises concerns about potential challenges in preventing further spread.
Dr. Boghuma Titanji, assistant professor of medicine at Emory University, stated that this discovery represents a fear realized: “The more mpox circulation we permit, the more opportunities the virus has to recombine and adapt, further entrenching mpox virus as a human pathogen that is not going away.”
Vaccination Remains Key
The JYNNEOS vaccine can protect against both mpox and smallpox. Administered in two doses, four weeks apart, vaccination reduces the risk of infection and can lessen symptom severity if infection occurs.
The Centers for Disease Control and Prevention (CDC) recommends the mpox vaccine for gay, bisexual, transgender, or other men who have sex with men who have had or expect to have:
- One or more sexually transmitted infections
- More than one sexual partner
- Anonymous sexual or intimate contact
- Sex at a commercial sex venue
- Sex in association with a large public event in a geographic area where mpox transmission is occurring
Vaccination campaigns targeting these groups were instrumental in halting the spread of mpox in the United States in 2022.
Individuals meeting these criteria who haven’t been vaccinated should do so as soon as possible. Both Clade IIb and Clade Ib continue to spread in the United States at low rates, making vaccination a crucial preventative measure.
Frequently Asked Questions
What are the symptoms of mpox?
Symptoms typically begin with fever, headache, muscle aches, and backache, followed by swollen lymph nodes and a rash.
How is mpox spread?
Mpox spreads through contact with sores, fluids from sores, or through saliva and respiratory secretions.
Is the mpox vaccine effective against the new recombinant strain?
While there are no specific studies on the new strain, it’s believed the vaccine will offer a high degree of protection.
Who is eligible for the mpox vaccine?
The CDC recommends vaccination for gay, bisexual, transgender, or other men who have sex with men who meet certain risk criteria.
What should I do if I think I have mpox?
Contact NHS 111 for advice.
Did you know? Genomic surveillance is crucial for tracking viral evolution and informing public health responses.
Pro Tip: Staying informed about mpox and vaccination recommendations is the best way to protect yourself and your community.
Stay informed about mpox and consult with healthcare professionals for personalized advice. Explore additional resources on the UKHSA website and the CDC website.
