As of July 2025, a new COVID strain, NB.1.8.1, nicknamed "Nimbus," has emerged as a significant topic in global health discussions. This variant has swiftly become the dominant strain in the United States, accounting for 43% of infections by late June 2025, according to the Centers for Disease Control and Prevention (CDC). First identified in China in January 2025, this new COVID strain has spread rapidly across continents, raising questions about its transmissibility, symptoms, and implications for public health. While it appears more contagious, health authorities, including the World Health Organization (WHO), suggest it poses a low global risk and does not lead to more severe illness. Here’s everything you need to know about the new COVID strain NB.1.8.1, its impact, and how to stay protected.
What Is the New COVID Strain NB.1.8.1?
The new COVID strain NB.1.8.1, also known as Nimbus, is a subvariant of the SARS-CoV-2 virus, which causes COVID-19. It was first detected in China in January 2025 and reached the U.S. by late March through international airport screening programs. On May 23, 2025, the WHO classified this new COVID strain as a “variant under monitoring” due to its rapid global spread and mutations in the spike protein, which may enhance its ability to bind to human cells. As a descendant of the LP.8.1 variant, NB.1.8.1 represents the ongoing evolution of the virus, a trend seen since the pandemic began in 2019.
Spread and Prevalence of the New COVID Strain
The new COVID strain NB.1.8.1 has shown remarkable growth in prevalence. In the U.S., it accounted for nearly 0% of cases in April 2025 but surged to 37% by mid-June and 43% by late June, as reported by the CDC. As of July 3, 2025, this new COVID strain has been detected in 28 states and the District of Columbia, including Arizona, California, Florida, New York, and Texas, among others. Globally, NB.1.8.1 has driven surges in Asia, particularly in China, and is increasing in regions like the Eastern Mediterranean, South-East Asia, and the Western Pacific, with WHO noting a global test positivity rate of 11% by May 2025. Posts on X have highlighted its presence in the UK, indicating its worldwide reach.
Characteristics and Transmissibility
Research suggests that this new COVID strain is likely more transmissible than its predecessors due to mutations that improve its ability to infect human cells, as noted in a non-peer-reviewed study (bioRxiv). Experts, including Subhash Verma from the University of Nevada, describe NB.1.8.1 as a “slightly upgraded version” of LP.8.1. However, there is no evidence that this new COVID strain causes more severe illness. The WHO has assessed its global risk as “low,” and emergency department visits for COVID-19 in the U.S. have decreased by 9.8%, reflecting a manageable impact.
| Characteristic | Details |
|---|---|
| Name | NB.1.8.1 (Nimbus) |
| First Detected | China, January 2025 |
| U.S. Detection | Late March 2025, via airport screening |
| U.S. Prevalence | 43% of cases as of June 21, 2025 |
| Global Risk (WHO) | Low |
| Transmissibility | Likely higher due to spike protein mutations |
| Severity | No evidence of increased severity compared to previous variants |
Symptoms of the New COVID Strain
The new COVID strain NB.1.8.1 presents symptoms similar to those of earlier variants, primarily affecting the respiratory system. Common symptoms include:
- Sore throat (often described as a “razor blade” sensation)
- Cough
- Runny nose or congestion
- Shortness of breath
- Fever or chills
- Headache
- Body aches
- Fatigue
- New loss of smell or taste
These symptoms, reported by sources like Today.com, align with those of previous strains, indicating that while NB.1.8.1 is more transmissible, its clinical presentation remains consistent. If symptoms appear, testing for COVID-19 is recommended to confirm infection and guide treatment.
Vaccination and Protection Against the New COVID Strain
Current COVID-19 vaccines are expected to remain effective against this new COVID strain, particularly in preventing severe disease and hospitalization, according to the WHO. For the 2025-2026 season, updated vaccines targeting the LP.8.1 variant have been approved for adults aged 65 and older and individuals aged 12-64 with underlying conditions, as noted by NBC News. These vaccines are designed to provide robust protection against NB.1.8.1 and related variants. Vaccination remains a critical tool, especially for high-risk groups, to mitigate the impact of this new COVID strain.
Current COVID-19 Trends
Despite the rise of this new COVID strain, overall COVID-19 activity in the U.S. remains low. As of June 21, 2025, the CDC reported a test positivity rate of 3%, a slight increase from the previous week, and wastewater surveillance indicates “very low” viral activity nationally (CDC Wastewater Data). However, global trends show increased activity since mid-February 2025, with a test positivity rate of 11% by May, particularly in the Eastern Mediterranean, South-East Asia, and Western Pacific regions. These regional differences highlight the need for ongoing monitoring of the new COVID strain.
| Metric | U.S. Data (June 21, 2025) | Global Data (May 2025) |
|---|---|---|
| Test Positivity Rate | 3% | 11% |
| Wastewater Activity | Very low | Not specified |
| Emergency Visits | Down 9.8% | Not specified |
Public Health Recommendations
The CDC and WHO emphasize continued vigilance to manage the new COVID strain. Key recommendations include:
- Vaccination: Stay up-to-date with COVID-19 vaccines, including boosters, especially for high-risk groups.
- Testing: If you experience symptoms like a sore throat, cough, or fever, get tested for COVID-19 to confirm infection and seek appropriate care.
- Hygiene: Practice handwashing and wear masks in crowded indoor settings to reduce transmission.
- Monitoring: Stay informed about local COVID-19 trends via trusted sources like the CDC or WHO.
The Nigerian naira appreciation (N1,526 per dollar) makes healthcare resources, such as testing kits and medications, more affordable for Nigerians, as noted in recent economic reports. Use SaveMoneyCalculator.com to budget for health-related expenses during this period.
Public Reactions and Controversies
The new COVID strain has sparked varied reactions. Social media posts on X, such as one from @MarioNawfal on July 5, 2025, highlight its “razor throat” nickname and rapid spread across 21 states, though some sources report 28 states, creating minor discrepancies. In the UK, calls for mask mandates have emerged, as noted by @BigBadDenis, reflecting concerns about immune evasion. However, the WHO’s low-risk assessment has reassured many, though some posts, like @toobaffled’s, urge caution due to the strain’s global spread. These mixed sentiments underscore the need for clear, evidence-based communication about the new COVID strain.
Conclusion
The new COVID strain NB.1.8.1 (Nimbus) marks another chapter in the evolving COVID-19 pandemic. While its increased transmissibility has made it the dominant strain in the U.S. and a growing concern globally, its low severity and the effectiveness of current vaccines offer reassurance. By staying vaccinated, practicing good hygiene, and monitoring symptoms, individuals can protect themselves and their communities. The Nigerian naira appreciation provides an opportunity to access affordable healthcare resources, and tools at SaveMoneyCalculator.com can help manage related costs. Stay informed and proactive to navigate the challenges of this new COVID strain.
Citations:
- CDC Variant Proportions
- CDC Risk Factors
- WastewaterSCAN Data
- Today.com - New COVID Variant
- WHO COVID-19 Dashboard
- bioRxiv Study on NB.1.8.1