New Delhi, June 7 -- The World Health Organisation has assessed the global health risk from Covid-19 variant NB.1.8.1, Sars-CoV-2 virus most prevalent today, as low, despite rising cases in several countries. The UN health body said on Friday that current evidence does not suggest the variant causes more severe illness than others in circulation. While cases and hospitalisations are increasing in some regions, this may be attributed to factors such as lower vaccination rates rather than the variant's severity. NB.1.8.1, first detected in a sample collected on January 22, 2025, is a descendant of the XDV.1.5.1 lineage, which itself descended from JN.1-a lineage of the Omicron variant BA.2.86. The variant carries six additional spike mutations that could affect its behaviour. Notably, mutations at position 445 may enhance binding to the hACE2 receptor, potentially increasing transmissibility. Meanwhile, changes at positions 435 and 478 could help the variant evade certain antibodies. In India, NB.1.8.1 is circulating alongside other variants including JN.1, LF.7, and XFG. The virus has shown increased prevalence both domestically and globally since mid-April, according to sources familiar with the monitoring. "This is still under monitoring by WHO as no escalation has been observed in the rate of hospitalisation or death so far," said a senior official, speaking anonymously. "India numbers convey pretty much the same-there is no cause for panic at the moment. However, one definitely needs to remain alert." Global Sars-CoV-2 activity has been rising since mid-February, with test positivity rates reaching 11%-levels not seen since July 2024. The increase is primarily driven by countries in the Eastern Mediterranean, South-East Asia, and Western Pacific regions. The share of the NB.1.8.1 variant in global sequences has grown to 10.7% as of mid-May. While recent increases broadly match patterns from the same period last year, the international organisation notes that SARS-CoV-2 circulation lacks clear seasonality and surveillance remains limited. The organisation emphasises that current vaccines remain effective against the variant in preventing severe disease and death. WHO continues to recommend a risk-based, integrated approach to Covid-19 management, with vaccination particularly crucial for at-risk groups. Recommended preventive measures include maintaining physical distance, wearing masks when unwell or in crowded, poorly ventilated spaces, ensuring good room ventilation, practising hand hygiene and respiratory etiquette, and staying current with vaccinations and booster doses....