A new COVID-19 variant, designated NB.1.8.1, is causing concern as it contributes to recent case surges in parts of Asia and has now been detected in the United States. The World Health Organization (WHO) highlighted the variant’s growing emergence in its latest COVID-19 status report, underscoring that the virus remains a significant public health risk.
NB.1.8.1: Tracking the Emergence of a New Variant
Scientists have recently identified NB.1.8.1 in California and other U.S. states. Although first detected in late January, the WHO officially recognized NB.1.8.1 as a variant under monitoring (VUM) more recently due to its increasing prevalence. As of mid-May, NB.1.8.1 accounted for approximately 10% of all COVID-19 cases reported globally to the WHO, a significant rise from 2% just four weeks prior. This coincides with an upswing in general COVID-19 activity, with the worldwide test positivity rate reaching 11% by May 11, a level not observed since July 2024. The Centers for Disease Control and Prevention (CDC) reported to NBC News that fewer than 20 cases of NB.1.8.1 have been identified in the U.S. so far, but the variant is linked to increases in cases and hospitalizations in countries like China.
Assessing Transmissibility and Severity
NB.1.8.1 is genetically part of the Omicron lineage, which first emerged in late 2021. This suggests it is unlikely to trigger outbreaks on the massive scale seen with Omicron’s initial arrival. However, NB.1.8.1 may possess mutations that could enhance its transmissibility compared to other currently circulating variants.
Despite these concerns, the WHO has stated, “Evaluation of…the most recently designated VUM, NB.1.8.1, suggests no increased public health risk posed by these variants compared to other circulating variants.” Currently, there is no evidence indicating that NB.1.8.1 causes more severe illness than other existing COVID-19 strains.
COVID-19’s Persistent Public Health Challenge
Even with its overall danger having declined since 2022, COVID-19 continues to pose a substantial public health problem. Between October 2024 and May 2025, COVID-19 is estimated to have caused between 30,000 and 50,000 deaths and up to 430,000 hospitalizations in the U.S., a burden comparable to an average influenza season. The recent emergence of NB.1.8.1 could potentially fuel a new peak in cases in the U.S. and other regions, particularly as summer approaches.
Vaccination Landscape and Policy Shifts
Adding to the potential danger are recent rock-bottom vaccination rates, even among older adults who are most vulnerable to severe outcomes from COVID-19. According to the WHO, only 1.68% of older adults across 75 countries received a COVID-19 booster shot in 2024. While primary COVID-19 vaccination series continue to offer protection against severe illness and death, booster doses further mitigate this risk.
The situation in the U.S. faces additional challenges. Under Health and Human Services Secretary Robert F. Kennedy Jr., known for spreading vaccine misinformation, the CDC recently removed its recommendation for COVID-19 vaccines for pregnant women and young children. Furthermore, Trump-era health officials have indicated plans to recommend COVID-19 vaccines primarily for older Americans, and the current administration has reportedly hindered the development of newer vaccines for both influenza and COVID-19.
Conclusion
While COVID-19 may no longer be the world-altering threat it once was, its presence persists. The emergence of variants like NB.1.8.1 serves as a stark reminder of this ongoing reality. “As per the latest WHO global risk assessment, covering the period July-December 2024, the global public health risk associated with COVID-19 remains high,” the WHO concluded in its report, urging continued vigilance.
