A new COVID-19 strain, NB.1.8.1, is rapidly spreading throughout the United States. This strain was essentially unknown just a few months ago. It’s now estimated to be the second most prevalent strain in the nation.
First identified in China in January 2025, NB.1.8.1 went stealthy throughout March. But by early June, it had shot up to represent roughly 37% of all COVID-19 instances in the United States, based on the Centers for Disease Control and Prevention (CDC).
What Is NB.1.8.1?
NB.1.8.1 is a close relative of LP.8.1, the most common Omicron strain. It is referred by University of Nevada professor of microbiology and immunology Subhash Verma as a “slightly upgraded version” of its parent. It is said to be more contagious and better at evading immune systems.
That is, NB.1.8.1 can be more difficult to shake off, even by vaccinated or previously infected people. This makes it a variant to watch closely, experts note.
NB.1.8.1 Symptoms: Familiar, But With a Twist
Symptoms of NB.1.8.1 are largely the same as with other COVID variants. These include:
- Fever or chills
- Cough
- Fatigue
- Muscle aches
- Loss of taste or smell
- Headache
- Sore throat
- Runny nose
- Nausea
But NB.1.8.1 delivers an unusually severe sore throat, one people term “razor blade throat.” It’s a phrase trending on social media, with many reporting severe pain when swallowing.
Even though the new name, NB.1.8.1, wasn’t officially listed by the CDC as a distinctive symptom, anecdotal evidence and media reports indicate it’s becoming a distinguishing characteristic of this variant.
How Widespread Is NB.1.8.1?
The rate at which NB.1.8.1 has increased is astonishing. In March, it comprised 0% of U.S. reported cases. By April, it had increased to 2%. It accelerated to 15% by the end of May. Now it’s at 37%.
The present most prevalent strain, LP.8.1, comprises 38%. NB.1.8.1 is catching up fast. The other variants such as XFG, XFC, and LF.7.9 come in behind.
Worldwide, the variant accounted for more than 10% of cases reported by the World Health Organization (WHO).
Do Vaccines Work against NB.1.8.1?
The WHO opines that currently available vaccines will still be effective against NB.1.8.1, particularly for preventing serious illness. That said, the fact that the variant can evade immune defenses is a cause for concern.
CDC still advocates for the use of the 2024-2025 COVID-19 vaccine, particularly the Moderna vaccine, for all above six months of age. That encompasses unvaccinated individuals, pregnant individuals, the elderly, and the immunocompromised.
Changing Vaccine Guidelines
In a contentious decision, Health and Human Services Secretary Robert F. Kennedy Jr. made announcements in late May. Healthy children and pregnant women will no longer be vaccinated against COVID-19. The emphasis is now on individuals over 65 or with underlying health conditions.
This shift has attracted criticism from healthcare professionals and could restrict access to the vaccine for many. Individuals who continue to wish to have the vaccine but do not qualify under the new recommendations might be forced to pay privately or experience restricted availability.
Free Testing Still Available
COVID-19 testing continues to be essential. Fortunately, the federal ICATT program continues to provide free COVID-19 testing at more than 19,000 sites across the country. Uninsured patients can go to testinglocator.cdc.gov/Search to get a free testing location near them.
What’s Next?
NB.1.8.1 is being closely watched. Although its global health threat is ranked “low” by the WHO, its quick spread and immune-evading capabilities are alarming. Experts caution to remain vigilant.
Keeping an eye on symptoms, regular testing, and staying current on vaccines are crucial. Though the pandemic is no longer in full force, the virus remains in motion, and so must we.
Final Thoughts
NB.1.8.1 is spreading rapidly and asserting itself. Although the current vaccines provide immunity, shifting guidance and the variant’s behavior indicate that COVID-19 is a constantly evolving target. Awareness, vigilance, and access to health care will continue to be essential in navigating the virus’s next chapter in the U.S.
