WHO Monitors New Covid-19 Variant NB.1.8.1, Known as Nimbus

The World Health Organization (WHO) is currently monitoring a novel variant of the Covid-19 virus, designated NB.1.8.1 and informally termed 'Nimbus.' This variant, which has emerged as a descendant of the Omicron lineage, is believed to exhibit increased transmissibility compared to earlier strains. As of June 2025, Nimbus accounts for over 10% of Covid-19 cases in Asia, with confirmed instances reported in multiple countries, including the United States and Canada.

According to Dr. Maria Van Kerkhove, the WHO's Technical Lead for Covid-19, the organization has classified NB.1.8.1 as a Variant Under Monitoring (VUM) due to its potential to evade immune responses generated from previous infections. "While we are seeing a rise in cases, the overall global risk remains low at this moment," Dr. Van Kerkhove stated during a recent press briefing.

Reports indicate that individuals infected with Nimbus frequently experience a severe sore throat, described by some as feeling like 'razor blades'. Other reported symptoms include flu-like manifestations such as congestion, fatigue, mild cough, fever, and muscle aches, with gastrointestinal symptoms like diarrhea and nausea appearing less frequently. Dr. Rajendram Rajnarayanan, an expert from the New York Institute of Technology, noted that the mutation might facilitate higher transmissibility, although emergency department visits related to Covid-19 have not surged significantly during this period.

Dr. T. Ryan Gregory, an evolutionary biologist at the University of Guelph, emphasized the need for vigilance. "We have learned from the Omicron variant that high transmissibility can have severe impacts, not only acutely but also in terms of long-term health consequences, such as 'long Covid'—a condition where symptoms persist for months or even years."

The variant’s ability to recombine genetic material from previous strains poses an additional concern. Each recombination event holds the potential for the virus to evolve into a more infectious or virulent form. The WHO continues to advocate for essential public health measures, including good respiratory hygiene, social distancing, and adherence to vaccination protocols as crucial strategies in mitigating the spread of NB.1.8.1.

As research on this variant progresses, health authorities and the scientific community remain alert to its implications for global public health. The situation is evolving, and continued monitoring will be vital to understanding the full impact of the Nimbus variant on the ongoing pandemic. Individuals are reminded to stay informed and consult healthcare professionals regarding any health concerns related to Covid-19 symptoms.

In conclusion, while the emergence of the NB.1.8.1 variant raises questions and concerns, experts underscore that currently available Covid-19 vaccines are still effective in preventing severe disease. The WHO urges the public to remain vigilant and adhere to recommended health guidelines to combat the spread of this new variant.