A new coronavirus strain, designated as NB.1.8.1, is rapidly spreading across several countries, including three popular tourist destinations, prompting the World Health Organization (WHO) to issue an official warning.
Experts warn that this strain may spread faster and more easily than previous variants.
According to the WHO, the new strain accounts for more than 10 percent of all infections and is currently classified as a "variant under monitoring" due to the sharp rise in cases.
Mutated Virus NB.1.8.1 Infects Cells More Efficiently
By the end of April 2025, NB.1.8.1 accounted for about 10.7% of all reported virus sequences – a significant increase from just 2.5% four weeks earlier. This variant is already dominant in Hong Kong and China.
Lara Herero, associate professor and head of research in virology and infectious diseases at Griffith University, states that the NB.1.8.1 strain can infect cells more efficiently due to multiple mutations compared to earlier strains.
"It is possible that a person infected with the NB.1.8.1 strain is more likely to transmit the virus to another person compared to earlier variants," says Professor Herero.
Current data suggest that this strain spreads more easily and may partially evade immunity from previous infections or vaccination. This could explain its rapid rise in genetic analyses.
However, it is important to emphasize that the WHO has so far not found evidence that NB.1.8.1 causes more severe clinical symptoms compared to earlier variants. Symptoms are generally similar to those of other Omicron subvariants.
Most Commonly Reported Symptoms:
- sore throat
- fatigue
- fever
- mild cough
- muscle pain
- nasal congestion
In some cases, gastrointestinal symptoms such as nausea or diarrhea may also occur.
In addition to China and Hong Kong, a rise in cases has been recorded in Cambodia and Singapore, and the virus has also been detected in Australia, the United States, and potentially the United Kingdom.
The WHO urges countries to remain vigilant and adapt to changes in the epidemiological situation by using COVID-19 management strategies to strengthen protection systems against all respiratory diseases. Member states are encouraged to continue vaccinations in accordance with current guidelines.
The WHO also emphasizes that, based on the current risk assessment, the introduction of travel and trade restrictions is not recommended.