The strain has been detected in multiple countries, including Australia, the US and possibly the UK
16:51, 30 May 2025Updated 16:51, 30 May 2025
A positive COVID test.(Image: Getty Images)
The World Health Organisation (WHO) has issued a warning to travellers about a new Covid strain that has caused a spike in the disease in several holiday hotspots.
The highly-infectious new strain – officially named NB.1.8.1 – has been detected in multiple countries, including Australia, Thailand and the Maldives.
The WHO said recent increases have also been observed in Cambodia, China, Hong Kong and Singapore.
The report reads: “WHO recommends that countries remain vigilant, adapt to evolving epidemiological trends, and leverage COVID-19 management strategies to strengthen systems for all respiratory disease threats.
“Member States should continue offering COVID-19 vaccines in line with WHO recommendations.
“Based on the current risk assessment of this event, WHO advises against imposing travel or trade restrictions.”
While no new travel restrictions have been put in place, those travelling to and from the affected countries are being urged to report any symptoms to a doctor.
Common symptoms include a sore throat, fever, mild cough, muscle aches and nasal congestion.
Lara Herrero, Associate Professor and Research Leader in Virology and Infectious Disease at Griffith University, said thanks to multiple mutations the new strain ‘may infect cells more efficiently than earlier strains’.
Professor Herrero added: “It’s possible a person infected with NB.1.8.1 may be more likely to pass the virus on to someone else, compared to earlier variants.
“The evidence so far suggests NB.1.8.1 may spread more easily and may partially sidestep immunity from prior infections or vaccination. These factors could explain its rise in sequencing data,” she added.
“But importantly, the WHO has not yet observed any evidence it causes more severe disease compared to other variants.”
The strain has also been identified in parts of the Eastern Mediterranean and the US.
There have also been some cases reported in the UK, but those reports have not been confirmed as of yet.