Covid-19: A New Variant Under Surveillance Detected in France After Surge in Asia

A new Covid-19 subvariant, known as NB.1.8.1, is drawing attention from global health authorities. After spreading significantly in Asia in recent weeks, particularly in China and Taiwan, the strain has now been identified in Europe — including four confirmed cases in France, according to the National Reference Center in Lyon, which monitors emerging variants.

A strain that emerged in Asia and is causing concern

First detected in France in March, NB.1.8.1 is a sub-lineage of the Omicron variant, already known for its high transmissibility. It has triggered a notable resurgence in infections in mainland China and Hong Kong, where local authorities report the highest level of viral circulation in over a year. In Taiwan, emergency visits and Covid-related deaths have also increased.

Virologist Bruno Lina notes that the variant could have a “growth advantage”, meaning it enters cells faster and replicates more efficiently. These traits could help it outcompete other circulating strains. Chinese data further suggest the variant may have an immune escape capacity, allowing it to partially evade protection from previous infections or vaccinations.

Limited but scattered detection in Europe

NB.1.8.1 has also been found in several European countries since April, including Germany, Ireland, the Netherlands, Spain, and Sweden, according to the European Centre for Disease Prevention and Control (ECDC). The United States has reported cases as well, identified through airport-based disease surveillance programs.

Still, health authorities are urging caution rather than alarm. Overall viral circulation remains low across the European Union in 2025, and NB.1.8.1 is not currently classified as a variant of concern by European health agencies.

Increased monitoring, but no major alert

On Friday, the World Health Organization (WHO) placed NB.1.8.1 in its “variant under monitoring” category, designed for strains that present a potential increased public health risk. However, the WHO emphasizes that there is no current evidence that this variant causes more severe illness than other circulating strains.

Regarding immunity, the organization believes that currently approved Covid-19 vaccines should remain effective against symptomatic and severe disease caused by NB.1.8.1.

In France, where the latest Covid-19 vaccination campaign is ongoing until June 15 (with a possible extension to July 15), health officials are urging vigilance, especially among vulnerable populations.

A context of moderate resurgence

Although testing is less widespread — and no longer reimbursed for most of the population — the WHO reports that 19% of Covid-19 tests conducted in France last week returned positive results.

While memories of the pandemic remain fresh, experts call for calm and continued robust epidemiological monitoring. The virus, it seems, is still evolving.