Overview

• NB.1.8.1 first emerged in January 2025 and rose from 2.5 percent to 10.7 percent of global sequences by late April, according to WHO data.
• The variant has been identified in at least 22 countries, with 13 confirmed infections in England and recent surges in India, Hong Kong, Singapore and Thailand.
• Clinicians report a distinctive “razor blade” sore throat along with fatigue, mild cough, fever, muscle aches, congestion and gastrointestinal symptoms including nausea, vomiting and diarrhoea.
• Despite its transmissibility, there is no indication NB.1.8.1 causes more severe illness, and health experts say existing Covid-19 vaccines continue to guard against serious disease.
• Public health officials warn that declining testing may mask the variant’s true spread and urge eligible groups, especially the elderly and immunocompromised, to stay current with vaccinations.