NB.1.8.1’s dominance is particularly pronounced in Asia—China’s immediate neighbors.
As the international community closely monitors the global spread of Omicron variant NB.1.8.1, China announced on May 23 that it is the primary variant spreading in the country.
On the same day, a World Health Organization advisory group classified NB.1.8.1 as a variant under monitoring, due to its increasing detection in monitoring efforts around the globe.
The WHO said they currently consider the NB.1.8.1 variant, first detected in January this year, to have a low risk to public health “at the global level.” It is not currently deemed a variant of interest or concern. The variant is a descendant of JN.1, a sublineage of Omicron.
As of May 18, 518 sequences of the new variant had been submitted by 22 countries to GISAID, a global influenza and COVID-19 virus genome sequence database, accounting for 10.7 percent of global sequences in epidemiological week 17 (April 21–27, 2025). This represents a significant increase in detection of the variant from 2.5 percent in week 14 (March 31–April 6, 2025).
NB.1.8.1’s dominance is particularly pronounced in Asia—China’s immediate neighbors.
China revealed a sharp increase in reported COVID cases, mostly driven by the NB.1.8.1 variant, with residents reporting symptoms including severe burning throat pain, cough, and fever.
The latest monthly update from the Chinese Center for Disease Control and Prevention (China CDC) reported that the average COVID-19 positivity rate for outpatient and emergency influenza-like cases rose from 7.5 percent to 16.2 percent in the month of April, while the positivity rate for hospitalized cases increased from 3.3 percent to 6.3 percent.
The data showed a rising yet variable trend, noting 168,507 confirmed cases nationwide, including 340 “severe cases” and nine deaths attributed to patients with a COVID-19 infection and underlying conditions. The Omicron sub-branch NB.1.8.1 dominated the results from gene sequencing.
Due to the Chinese authorities’ past record of underreporting infections and covering up information, it is difficult to assess the true scale of the current outbreak.
By Mary Man
