Covid-19 is quietly resurging in parts of Asia, including Hong Kong, Singapore, China, and Thailand, with rising infections and severe cases drawing renewed attention.

An emerging variant, NB.1.8.1, is circulating in parts of the world. This week, the World Health Organization (WHO) said that the rise in cases is concentrated in the eastern Mediterranean, South-East Asia, and western Pacific regions.

The WHO has designated NB.1.8.1—a sublineage of Omicron—as a “variant under monitoring” (VUM) due to its increasing global prevalence and certain genetic traits that may distinguish it from earlier strains.

First detected in samples collected in January 2025, the variant is spreading particularly quickly in Asia, prompting heightened surveillance by international health agencies.

In Australia, available data from early May indicate that NB.1.8.1 accounted for less than 10 percent of cases in South Australia but more than 40 percent in Victoria.

Wastewater analysis in Western Australia suggests the variant has become dominant in the state capital, Perth. National health authorities say that as fewer people now undergo testing, tracking the virus has become more difficult.

International data from GISAID, a global database of viral genetic sequences, show that the first recorded cases of NB.1.8.1 were identified in travellers from France, Japan, the Netherlands, South Korea, Spain, Taiwan, and Thailand.

Meanwhile, LP.8.1 remains the dominant variant in the United States and globally. Health officials report that symptoms associated with NB.1.8.1 are largely consistent with earlier Omicron subvariants, including fever or chills, cough, shortness of breath, sore throat, congestion or runny nose, loss of taste or smell, headache, nausea, and fatigue.

Current Covid-19 vaccines are expected to continue offering protection against the new variant, according to the WHO.