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.
COVID-19 Cases Surging in Numerous Countries
COVID-19 infections, which have shifted in recent weeks to be dominated by the NB.1.8.1 variant, are also surging in Taiwan.The Taiwan Centers for Disease Control (Taiwan CDC)
reported that between May 11 to May 17 (epidemiological week 20), there were 19,097 COVID-19 outpatient and emergency room visits, marking an 88 percent increase from the previous week. However, it did note that this is lower than the 23,778 visits recorded in week 20 of 2024.
From May 12 to May 19, Taiwan recorded 93 new severe COVID-19 cases and four deaths, marking the highest outpatient visits and severe outcomes this year.
Taiwan CDC spokesperson Lo Yi-chun
told local reporters that the NB.1.8.1 variant spreads more easily because it is better at avoiding the body’s immune defenses—like antibodies from vaccines or past infections—so the new variant is harder for the body to fight off.
Scientists in China, from Peking University, Tsinghua University, and Changping Laboratory, said the same in a
report published on May 1 about NB.1.8.1’s traits, noting its high transmissibility and immune evasion. The researchers suggested that NB.1.8.1 could dominate future waves.
Thailand is grappling with a parallel increase in COVID-19, reporting 33,030 new cases in week 20, doubling from around 16,000 cases the previous week, Bangkok Post
reported.
Unlike Taiwan, Thailand’s surge is driven by another variant, with NB.1.8.1 not yet dominant.
U.S. airports have also detected multiple NB.1.8.1 cases, with health authorities in Ohio, Rhode Island, Hawaii, California, and Washington state confirming infections.
Recent
data from GISAID show NB.1.8.1 cases among travelers to the United States from Japan, South Korea, France, Thailand, the Netherlands, Spain, Vietnam, China, and Taiwan, tested between April 22 and May 12.
Europe is also reporting NB.1.8.1 cases since April 2025, particularly in France, Germany, Spain, Greece, and Ireland.
As of May 26, 2025, the WHO dashboard
shows France with the highest COVID-19 test positivity rate outside of Asia at 19 percent.
Mexico has a 15 percent positivity rate, followed by West Africa’s Burkina Faso at 12 percent, Ethiopia at 10 percent, and both Saudi Arabia and Kazakhstan at 7.5 percent.
India has also reported seeing a rise in the NB.1.8.1 variant, as well as LF.7—also a descendant of JN.1. The COVID-19 vaccines deployed since June 2024 have been based on the JN.1 variant.
The WHO
said in its monitoring update that, “Despite a concurrent increase in cases and hospitalizations in some countries where NB.1.8.1 is widespread, current data do not indicate that this variant leads to more severe illness than other variants in circulation.”
Experts encourage those feeling unwell to rest, stay hydrated, and self-isolate, and use antivirals as needed. Individuals with comorbidities are recommended to maintain personal hygiene and preventive measures to reduce their risk of infection.
