Emerging COVID Variant NB.1.8.1 Comprises Up to One-Third of U.S. Cases

The COVID-19 variant NB.1.8.1 is rapidly spreading across the U.S., now making up nearly one-third of cases with higher transmissibility but no increased severity. Ongoing surveillance is vital to manage this evolution.
A newly identified COVID-19 variant, designated NB.1.8.1, appears to be spreading rapidly across the United States, now potentially responsible for approximately one in three COVID cases nationally. Previously observed in Asia, this variant has caused a recent surge in hospitalizations in some regions.
The CDC's latest surveillance indicates that NB.1.8.1 could account for nearly half of the cases detected in international travelers arriving in the U.S. during late May. This detection stems from a global effort to monitor variants through airport sampling programs, where travelers participate in nasal swab testing to identify circulating strains.
Despite its increased prevalence, health experts emphasize that NB.1.8.1 does not seem to cause more severe illness compared to earlier variants. Its key characteristic is enhanced transmissibility, allowing it to spread more easily among populations. Professor Subhash Verma from the University of Nevada, Reno, noted that the variant's growth advantage suggests higher transmissibility rather than increased severity.
Symptoms linked to NB.1.8.1 remain similar to previous COVID-19 variants, including cough, sore throat, fever, and fatigue. As the virus continues to evolve, vaccine strategies may adapt, with the FDA confirming plans to approve updated vaccines tailored for higher-risk groups, such as seniors and immunocompromised individuals. However, large-scale trials are required, which could delay broader availability for the general population.
There has also been discussion about vaccination policies for children and pregnant women. While some officials suggest limiting vaccination to high-risk groups, the CDC states that children six months and older may still be vaccinated based on individual circumstances and medical advice.
For in-depth information on NB.1.8.1, consult the World Health Organization’s detailed report. The rapid spread of this variant underscores the importance of ongoing surveillance and vaccination efforts to control COVID-19.
Source: https://medicalxpress.com/news/2025-06-covid-variant-nb181-cases.html
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