Highly infectious COVID strain from China, linked to a hospitalization spike, spreads to the US — including NYC
A new, highly infectious strain of COVID-19, known as NB.1.8.1, has emerged from China and has now been detected in the United States, including New York City.
This variant has driven a significant surge in hospitalizations in China and Hong Kong, raising alarms among global health authorities.
While its presence in the US is confirmed, the extent of its impact remains unclear. Health officials are closely monitoring its spread.
The Emergence of NB.1.8.1
The NB.1.8.1 variant, a descendant of the Omicron lineage JN.1, was first identified in China, where it rapidly became the dominant strain.
Emergency room visits for COVID-19 in China doubled from 7.5% to over 16% in the past month.
Hospital admissions for the virus also doubled to over 6%. In Hong Kong, the variant has led to the worst COVID-19 levels in a year, with a significant increase in emergency room visits and hospitalizations.
Over the past four weeks, Hong Kong reported 81 severe cases and 30 deaths, primarily among adults over 65.
Dr. Edwin Tsui from Hong Kong’s Centre for Health Protection (CHP) stated that the variant “should not be taken lightly” and is being monitored in line with World Health Organization (WHO) guidelines.
In Taiwan, the variant has caused a 78% rise in COVID-19-related emergency room visits over a recent week.
These developments highlight NB.1.8.1’s high transmissibility. The variant’s ability to strain healthcare systems is a growing concern.
Characteristics of the Variant
NB.1.8.1 is noted for its high infectivity, with researchers suggesting it binds more effectively to human cells.
This makes it more transmissible than other variants. However, preliminary data from China indicates it is not better at evading the immune system compared to other strains.
There is no evidence it causes more severe illness. Dr. Subhash Verma, a professor at the University of Nevada, Reno School of Medicine, noted that symptoms are “broadly similar to those seen in earlier strains,” including coughing, sore throat, fever, and fatigue.
Dr. Amy Edwards from Case Western Reserve University echoed that while the variant is driving hospitalizations in Asia, it does not appear more dangerous.
Concerns have been raised about the variant’s ability to evade vaccine-induced immunity.
The Hong Kong CHP has warned of the possibility of more virulent or vaccine-mismatched strains.
The WHO has designated NB.1.8.1 as a variant under monitoring (VUM) due to its increasing global prevalence.
Spread to the United States
The CDC has confirmed that NB.1.8.1 cases were first detected in the US in late March and early April 2025 through its airport screening program.
Cases were identified among international travelers arriving in California, Washington State, Virginia, and the New York City area.
These travelers came from countries including Japan, South Korea, France, Thailand, the Netherlands, Spain, Vietnam, China, and Taiwan, with testing conducted between April 22 and May 12.
Additional cases have been reported in Ohio, Rhode Island, and Hawaii, indicating the variant’s presence beyond airport detections.
Despite these findings, the CDC notes that there are too few cases to include NB.1.8.1 in its variant estimates dashboard.
This suggests it is not yet a dominant strain in the US. Health officials assess the current public health risk from NB.1.8.1 as low, but they continue to monitor its spread closely.
Impact in New York City
In New York City, the NB.1.8.1 variant has been detected, with at least two confirmed cases reported by the New York State Health Department.
However, there is no evidence of a massive spike in hospitalizations directly linked to this variant.
The NYC Health Department’s latest data, updated as of May 22, 2025, tracks COVID-19 metrics, including hospitalizations.
Specific numbers for NB.1.8.1-related cases are not available due to the low number of cases.
Marissa Crary, a spokesperson for the New York State Health Department, confirmed the presence of the variant but emphasized that it does not appear to cause more severe illness than previous strains.
The city’s healthcare system remains vigilant. Ongoing surveillance through wastewater monitoring and hospital data collection aims to detect any potential uptick in cases.
| Region | Impact of NB.1.8.1 |
|---|---|
| China | Dominant strain; ER visits doubled from 7.5% to >16%; hospital cases doubled to >6%. |
| Hong Kong | Worst COVID levels in a year; 81 severe cases, 30 deaths in past 4 weeks (mostly 65+). |
| Taiwan | 78% increase in hospital admissions over a recent week. |
| United States | Detected in multiple states; low case numbers; no reported hospitalization spike. |
| New York City | At least 2 confirmed cases; no significant hospitalization increase reported. |
US Response and Policy Changes
The emergence of NB.1.8.1 coincides with significant changes in US COVID-19 vaccination policy.
The Trump administration has limited booster shots to elderly individuals and those with high-risk conditions.
The CDC no longer recommends the COVID-19 vaccine for healthy children and pregnant women.
These changes have sparked debate. Some experts express concern about reduced vaccine access amid the spread of a potentially vaccine-evasive variant.
The Food and Drug Administration (FDA) has selected the LP.8.1 strain for fall 2025 vaccines.
This decision may limit the shots’ effectiveness against NB.1.8.1.
Health experts, including Dr. James McDonald, New York State Health Commissioner, continue to advocate for vaccination as a key defense against severe illness, particularly for vulnerable populations.
Global Perspective
The NB.1.8.1 variant’s impact extends beyond China and the US. In addition to Taiwan, countries like Singapore have reported rising cases linked to this strain.
Hong Kong authorities have reinstated mask recommendations for public transport and crowded settings.
Taiwan is stockpiling vaccines and antiviral treatments in response to the surge.
The WHO’s designation of NB.1.8.1 as a variant under monitoring underscores the need for global coordination to track and respond to its spread.
Public Health Recommendations
Health officials recommend several measures to mitigate the spread of NB.1.8.1:
Vaccination: Eligible individuals, particularly the elderly and high-risk groups, should stay up to date with COVID-19 vaccines.
Masking: Wearing masks in crowded indoor settings can reduce transmission, especially in areas with rising cases.
Testing and Isolation: Individuals with symptoms like cough, sore throat, or fever should get tested and follow isolation guidelines if positive.
Monitoring: Stay informed through reliable sources like the CDC and local health departments for updates on the variant’s spread.
The NB.1.8.1 variant’s arrival in the US, including New York City, is a cause for concern due to its high transmissibility and the significant hospitalization spikes observed in China and Hong Kong.
However, the lack of a similar surge in the US suggests that the variant’s impact is currently limited.
Continued surveillance, vaccination, and adherence to public health measures are critical to managing its spread.
As more data becomes available, health authorities will better understand NB.1.8.1’s implications and refine strategies to protect communities.
