**New Covid Subvariant NB.1.8.1 Spreads to Popular Tourist Destinations: Experts Monitor Rise and Advise Vigilance**
A fresh wave of concern has swept through the global health community with the emergence of a new Covid-19 subvariant, officially named NB.1.8.1, which is now gaining traction in various parts of the world. According to recent updates from the World Health Organisation (WHO), this highly transmissible strain has been detected in several countries, notably Australia, the United States, and likely the United Kingdom. The mutation’s spread has been particularly prominent in high-traffic holiday areas, raising alarms for tourists and local officials alike.
The WHO recently reported that NB.1.8.1 now comprises more than 10% of all reported Covid cases worldwide, marking a significant increase from just a few weeks prior. By the end of April 2025, this variant accounted for 10.7% of sequenced cases, up from only 2.5% at the start of the month. In regions such as Hong Kong and China, NB.1.8.1 has emerged as the dominant strain, surpassing previous variants in prevalence.
Virologists monitoring the situation suggest that the new variant’s rapid rise is likely due to its unique mutations. Lara Herrero, associate professor and research leader at Griffith University, stated that these genetic adaptations could allow NB.1.8.1 to infect human cells more efficiently than earlier versions of the virus. However, despite its increased transmissibility, there is currently no evidence to suggest that the variant leads to more severe illness compared to prior strains.
The WHO has classified NB.1.8.1 as a “variant under monitoring”, signifying that experts are closely watching its development and potential impact. Nevertheless, the agency has not, at this stage, called for new travel or trade restrictions, emphasising that routine international movement need not be disrupted. The organisation has urged nations to remain alert and respond flexibly to evolving patterns in variant transmission, relying on established public health measures.
As for symptoms, scientists believe NB.1.8.1 does not differ significantly from other recent Omicron subvariants. Those infected are likely to experience a range of symptoms including sore throat, tiredness, mild fever, cough, aching muscles, and stuffy nose. In certain cases, individuals may also report digestive issues. The consistency in symptoms should, for now, provide reassurance to those already familiar with the disease’s typical presentation.
WHO’s latest brief outlines the shifting landscape of global SARS-CoV-2 variants over the past year. While the XEC variant was most prevalent at the beginning of 2025, it gradually gave way to others, with LP.8.1 gaining dominance in early spring. Since mid-April, however, NB.1.8.1 has clearly been increasing in frequency, now establishing itself as a key focus for ongoing monitoring and research.
Of particular note is the subvariant’s spread in popular travel destinations. The eastern Mediterranean, including well-known spots like Egypt, is witnessing a notable rise in cases linked to NB.1.8.1. Meanwhile, the subvariant has also been identified in Southeast Asian countries such as Thailand and the Maldives—locations frequented by international holidaymakers. Health data reflects upward infection trends more broadly in areas like China, Cambodia, Hong Kong, and Singapore.
In response to the evolving situation, the WHO has recommended that member states maintain a strong focus on monitoring and adjusting their Covid-19 prevention strategies, especially as summer travel intensifies. The organisation continues to advise that countries provide vaccines in line with up-to-date recommendations, aiming to mitigate further spread and reduce the risk of severe community impact.
While the swift ascent of NB.1.8.1 is concerning, the lack of indications for heightened severity or a need for stricter border measures offers some reassurance. Still, experts stress the importance of ongoing vigilance—reminding the public to stay informed, practise good hygiene, and adhere to local health guidance, particularly when travelling to or from regions experiencing a surge.
As the landscape of Covid-19 continues to evolve, scientists and officials alike are emphasising the need for collective, adaptable responses to these new variants, ensuring systems remain prepared for both current outbreaks and potential future challenges.