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New Covid Variant NB.1.8.1 Triggers Global Alert Amid Rising Cases
A newly emerging Covid-19 variant, NB.1.8.1, is capturing the attention of health authorities worldwide as it continues to spread rapidly across the globe.
First detected in January 2025, this subvariant has since been identified in 22 countries, including popular international travel spots such as Thailand, Egypt, and the Maldives.
Though current research indicates NB.1.8.1 may not lead to more severe illness than earlier variants, its swift transmission rate is prompting increased surveillance and public health advisories.
Experts have flagged the variant for its potentially higher contagiousness, a characteristic that may contribute to its growing prevalence.
Rapid International Spread Raises Concerns
According to Wales Online, NB.1.8.1 cases are climbing steadily in the UK, with Wales among the most affected regions. Beyond Britain, this variant has been confirmed in countries like Ireland, Australia, the United States, and several parts of Europe. In Thailand, where over 257,000 Covid-19 cases and 52 deaths have been recorded so far this year, health officials have issued formal alerts as a precaution.
Professor Subhash Verma, an expert in microbiology and immunology at the University of Nevada, shared insights with CBS News, stating:
“While NB.1.8.1 doesn’t appear to be more dangerous in terms of illness severity, its growth advantage means it’s likely spreading faster than previous strains.”
Global Monitoring, But No Alarming Signs Yet
The World Health Organization (WHO) has designated NB.1.8.1 as a “variant under monitoring” due to its distinct genetic mutations and accelerating global footprint. Despite its rapid spread, the WHO currently rates the global public health risk as low, based on available data.
Importantly, the WHO continues to affirm that existing Covid-19 vaccines are expected to remain effective in protecting against both symptomatic and severe disease from this new variant.
Notably, no new travel restrictions have been implemented in response to NB.1.8.1 at this time, and the WHO has advised against imposing any such measures prematurely.
Dominance in Parts of Asia and Beyond
By the end of April, NB.1.8.1 accounted for 10.7% of all sequenced Covid-19 cases across the 22 countries tracking it—a sharp increase from just 2.5% only a month earlier. It has become especially prominent in regions such as Europe, the Western Pacific, and the Americas.
In China and Hong Kong, NB.1.8.1 has become the dominant strain, according to Professor Laura Herrero of Griffith University in Australia. She noted that the symptom profile remains similar to other Omicron subvariants, with common issues including:
- Sore throat
- Mild fever
- Fatigue
- Cough
- Muscle aches
- Nasal congestion
- Occasional gastrointestinal discomfort
Despite this, there has been no clear link between NB.1.8.1 and an increase in illness severity or hospitalizations so far.
Guidance and Precautions Still Matter
Health authorities, including the NHS, continue to recommend that individuals who test positive for Covid-19 should self-isolate for five days. For children and adolescents under 18, a three-day isolation period is advised.
Bottom Line
While NB.1.8.1 is not currently considered more dangerous in terms of health outcomes, its accelerated spread and transmissibility warrant continued vigilance.
Health agencies worldwide are tracking the variant closely, and public health advice remains unchanged: stay informed, practice caution, and follow official guidelines to reduce the risk of transmission.
Vaccination remains a key tool in managing the impact of evolving variants, and experts urge the public to stay up to date on boosters and to observe health recommendations, especially during travel or in high-risk settings.