A new COVID variant known as NB.1.8.1 is gaining traction globally, with health authorities closely monitoring its spread. First detected in China in January 2025, this Omicron subvariant has quickly increased its presence worldwide. This article provides essential information about NB.1.8.1, including its symptoms, transmission patterns, and how it compares to previous variants.
What Is the New COVID Variant NB.1.8.1?
Scientific visualization of the NB.1.8.1 variant showing its distinctive spike protein mutations
NB.1.8.1 is a sublineage of the Omicron variant, descending from the recombinant XDV lineage. According to the World Health Organization (WHO), which recently designated it as a “variant under monitoring,” NB.1.8.1 was first detected in samples collected in January 2025.
Recent surveillance data shows that NB.1.8.1 now accounts for approximately 10% of global SARS-CoV-2 sequences, up from just 2.5% four weeks ago. The variant has been spreading particularly rapidly in Asia, becoming the dominant strain in Hong Kong and China by late April.
In the United States, the Centers for Disease Control and Prevention (CDC) has identified only 20 NB.1.8.1 sequences so far, but this number is expected to rise as the variant continues to spread globally.
Mutations and Transmission of the New COVID Variant
Like previous variants, NB.1.8.1 carries several mutations in the spike protein, which is the part of the virus that allows it to infect human cells. The key mutations identified in NB.1.8.1 include T22N, F59S, G184S, A435S, V445H, and T478I.
Early research suggests these mutations may give NB.1.8.1 certain advantages over previous variants:
- Stronger binding affinity to the human ACE2 receptor, potentially allowing it to infect cells more efficiently
- Partial ability to evade immunity from prior infections or vaccination
- Potentially higher transmissibility compared to earlier variants
A recent laboratory study found that NB.1.8.1 had the strongest binding affinity to the human ACE2 receptor among several variants tested. The same study showed that the neutralizing response of antibodies was approximately 1.5 times lower against NB.1.8.1 compared to the LP.8.1.1 variant.
Stay Updated on Variant Tracking
For the most current information on COVID variant tracking and prevalence, visit the CDC’s COVID Data Tracker.
Symptoms of the New COVID Variant
According to infectious disease specialists, the symptoms of NB.1.8.1 align closely with those of other recent Omicron subvariants. The WHO has not observed any evidence that this variant causes more severe disease compared to previous variants.
Common Symptoms of NB.1.8.1
- Sore throat
- Fatigue and tiredness
- Mild but persistent dry cough
- Nasal congestion
- Fever and chills
- Muscle aches
- Headache
- Gastrointestinal symptoms (in some cases)
Dr. Amesh Adalja, an infectious diseases expert and senior scholar at the Johns Hopkins University Center for Health Security, notes that NB.1.8.1’s symptoms are “pretty much the same as those seen with other SARS-CoV-2 variants.”
Dr. Zachary Hoy, a pediatric infectious disease specialist, adds that some patients describe recent variants as causing “less intense symptoms compared to wintertime influenza viruses, but both can have severe symptoms.”
“An infected person can still make it through the day, but they are resting more and feel more tired throughout the day,” explains Dr. Hoy.
Vaccine Effectiveness Against the New Variant
While research on NB.1.8.1 is still limited due to its recent emergence, scientists expect current vaccines to remain effective against severe disease. NB.1.8.1 descended from the Omicron JN.1 lineage, which is targeted by the 2024-2025 COVID vaccines.
According to Dr. Adalja, “The ability of the vaccines to prevent severe illness is intact, though protection versus infection is limited and transient.”
The World Health Organization has noted that even if neutralizing antibody levels are modestly reduced against NB.1.8.1, current COVID vaccines should still protect against severe disease with this variant.
Vaccination Recommendations
Health authorities recommend that those at higher risk for severe COVID-19 should stay up-to-date with their vaccinations. This includes:
- Older adults
- People with underlying medical conditions
- Individuals with compromised immune systems
- Healthcare workers with increased exposure
If you fall into one of these categories and it has been more than six months since your last vaccine or COVID infection, experts suggest getting an updated vaccine.
Find COVID-19 Vaccines Near You
Staying up-to-date with COVID vaccines is one of the best ways to protect yourself against new variants.
Treatment Options and Weight Management Medications
For most people infected with NB.1.8.1, recovery at home with rest, hydration, and over-the-counter medications like acetaminophen or ibuprofen to manage symptoms is sufficient. Symptoms typically resolve within a week.
For those at higher risk of severe disease, antiviral medications remain an important treatment option:
- Paxlovid (nirmatrelvir and ritonavir)
- Molnupiravir
These antivirals work best when started within five days of symptom onset and can significantly reduce the risk of hospitalization and death.
COVID-19 and Weight Management Medications
Recent research has shown that individuals with obesity face higher risks from COVID-19. This has led to increased interest in weight management medications like Mounjaro, which contains the active ingredient tirzepatide.
While Mounjaro’s “golden dose” (the optimal dosage that balances efficacy and side effects) has shown promising results for weight loss, it’s important to note that these weight loss injections are not direct treatments for COVID-19. Rather, they may help reduce risk factors that can lead to more severe COVID outcomes.
When to Seek Emergency Care: If you experience difficulty breathing, persistent chest pain, confusion, inability to stay awake, or bluish lips or face, seek emergency medical attention immediately.
Prevention Measures Against the New COVID Variant
The preventive measures that worked against previous COVID variants remain effective against NB.1.8.1. Health authorities continue to recommend:
Personal Protection
- Wearing well-fitting masks in crowded indoor settings
- Practicing good hand hygiene
- Maintaining physical distance when possible
- Staying home when feeling unwell
Environmental Measures
- Ensuring good ventilation in indoor spaces
- Regular cleaning of high-touch surfaces
- Using air purifiers with HEPA filters
- Following local public health guidelines
These preventive strategies are particularly important for vulnerable populations and during periods of increased transmission, such as the upcoming winter months in the Northern Hemisphere.
Get Tested If You Have Symptoms
If you’re experiencing COVID-19 symptoms, testing can help protect others and determine if you need treatment.
Global Spread and Surveillance
NB.1.8.1 is currently spreading across multiple continents, with the highest concentration in Asia. By late April 2025, it comprised approximately 10.7% of all submitted sequences globally – a significant increase from just 2.5% four weeks earlier.
The variant has become particularly prevalent in:
- China and Hong Kong (dominant variant)
- Australia (ranging from 10% to 40% of sequenced cases depending on the region)
- Parts of Europe (increasing presence)
- United States (limited detection so far)
Health authorities worldwide are conducting genomic surveillance to track the variant’s spread and monitor for any changes in its characteristics or impact on public health.
In Australia, wastewater surveillance has determined that NB.1.8.1 is now the dominant variant in samples collected in Perth, while in Victoria it represents more than 40% of sequenced cases.
Frequently Asked Questions About the New COVID Variant
Is the new COVID variant more dangerous than previous variants?
According to the World Health Organization, there is currently no evidence that NB.1.8.1 causes more severe disease compared to other variants. While it may be more transmissible and have some immune evasion properties, the severity of illness appears similar to other recent Omicron subvariants.
How effective are current COVID tests at detecting the new variant?
Current PCR and rapid antigen tests should still detect the NB.1.8.1 variant. These tests target parts of the virus that typically don’t change significantly between variants. If you test positive on a home test or PCR test, you should consider yourself infected regardless of which variant you might have.
Should I get a booster shot specifically for this new variant?
If you’re at higher risk for severe COVID-19 and it’s been more than six months since your last vaccine or infection, health authorities recommend getting the current updated vaccine. The 2024-2025 vaccines target the JN.1 lineage, from which NB.1.8.1 descended, so they should provide some protection against severe disease.
How is the new variant affecting hospital admissions?
So far, there hasn’t been a significant increase in hospitalizations specifically attributed to NB.1.8.1. Health authorities are monitoring this closely, but current data suggests that while the variant may be more transmissible, it doesn’t appear to be causing a higher rate of severe disease requiring hospitalization.
Can weight loss medications like Mounjaro help reduce COVID-19 severity?
While weight loss injections like Mounjaro aren’t direct treatments for COVID-19, they may indirectly help by reducing obesity, which is a known risk factor for severe COVID-19. However, these medications should only be used under medical supervision for their approved indications, not specifically as COVID-19 preventatives.
Staying Informed About the New COVID Variant
As NB.1.8.1 continues to spread globally, staying informed through reliable sources is essential. The variant appears to be more transmissible and may partially evade immunity from prior infections or vaccinations, but there’s currently no evidence it causes more severe disease.
The symptoms remain consistent with other recent COVID variants, and existing preventive measures, testing, and treatments continue to be effective. For those at higher risk, staying up-to-date with vaccinations remains an important protective strategy.
Health authorities worldwide are closely monitoring the situation and will provide updates as more information becomes available about this new COVID variant.
Stay Protected Against COVID-19
For comprehensive information on protecting yourself and others from COVID-19, visit the CDC’s COVID-19 resource center.
