New Covid-19 Variant NB.1.8.1
A new sub-variant of Covid-19, named NB.1.8.1, was identified in India. This variant is a descendant of the Omicron lineage JN.1 and has raised concerns due to its potential transmissibility. The World Health Organization (WHO) classified it as a ‘Variant Under Monitoring’ (VUM), indicating that its mutations warrant further observation, although it is not currently deemed a ‘Variant of Interest’.
What Is NB.1.8.1?
NB.1.8.1 originated from the recombinant ancestor XDV.1.5.1. Its earliest samples date back to January 22, 2025. The variant has been noted for its six spike protein mutations compared to the LP8.1 variant, and eight mutations compared to JN.1. Preliminary data suggest that NB.1.8.1 may have a higher transmissibility rate due to its enhanced binding affinity to human receptors.
Key Characteristics
The mutations in NB.1.8.1 include A435S, V445H, and T478I. These alterations indicate a potential for increased transmissibility and some immune evasion. Reports from China suggest that NB.1.8.1 is spreading rapidly, particularly in regions like Singapore, where weekly cases surged from 11,100 to over 14,000 in early May 2025.
Symptoms of NB.1.8.1
Symptoms of NB.1.8.1 largely mirror those of previous Omicron variants. Common symptoms include sore throat, fatigue, mild cough, fever, nasal congestion, headache, nausea, and gastrointestinal issues. Notably, the loss of taste or smell is less frequently reported with this variant.
Public Health Impact in India
As of May 19, 2025, India reported 257 active Covid-19 cases, with a slight increase in states like Kerala and Tamil Nadu. The dominant variant remains JN.1, followed by BA.2. Health officials assert that NB.1.8.1 does not appear to cause more severe illness than previous variants. Most cases are mild and manageable at home, with low hospitalisation rates. Existing vaccines are expected to remain effective against this variant.
Unique Case in Bengaluru
A notable case emerged in Bengaluru where a nine-month-old baby tested positive for Covid-19. The infant is currently receiving treatment but is stable. Karnataka has seen a gradual rise in cases, prompting health officials to advise the public to adhere to preventive measures.
Surveillance and Monitoring
India has a robust surveillance system for respiratory illnesses through the Integrated Disease Surveillance Programme. The health ministry is actively monitoring the situation and has urged the public to maintain hygiene, wear masks in crowded areas, and consult healthcare providers if symptoms arise.
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