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.