The NB.1.8.1 variant of the SARS-CoV-2 virus was recently detected in the United States among international travelers, according to the Centers for Disease Control and Prevention (CDC).
- Where was the NB.1.8.1 variant detected in the United States?
- What is the origin and behavior of the NB.1.8.1 variant?
- What do the CDC say about the current hospital situation in the US?
- What is the currently dominant variant in the US?
- What does the WHO say about the circulation of these variants?
- Will vaccines change for the 2025-2026 season?
While the number of cases is limited, its presence coincides with an increase in infections in several regions of Asia, particularly in mainland China and Hong Kong.
According to the CDC, this subvariant has been identified in fewer than 20 genomic sequences in the national surveillance system. This is why it has not yet been included in the main panel of the COVID Data Tracker, the official tool used to monitor the circulation of variants in U.S. territory.
The detection was carried out through the federal airport monitoring program, which collaborates with the biotechnology company Ginkgo Bioworks.
The emergence of NB.1.8.1, along with other emerging variants from the JN.1 family, has led public health agencies to strengthen genomic surveillance systems. Although there is no evidence that this variant causes more severe illness, its circulation has prompted new precautionary measures in East Asian countries, and possible adjustments to vaccination strategies for the 2025-2026 season.
Where was the NB.1.8.1 variant detected in the United States?
The NB.1.8.1 variant was identified in airports in the states of California, Washington, Virginia, and in the New York metropolitan area, based on data from the CDC’s airport monitoring program. These detections are part of the federal effort to track new variants in travelers arriving from abroad.
The health agency explained that, although the variant has not yet reached a prevalence threshold that would justify its inclusion in the COVID Data Tracker, its evolution continues to be monitored. If the proportion of cases attributed to NB.1.8.1 increases, it will be incorporated into the surveillance panel.
What is the origin and behavior of the NB.1.8.1 variant?
NB.1.8.1 is a sublineage of the JN.1 variant, which descends from the Omicron strain, dominant since late 2021. According to the Indian Council of Medical Research (ICMR), this sublineage has also been detected in India, along with another subvariant called LF.7, in regions where localized surges in cases have been reported. The Ministry of Health and Family Welfare of India has asked state governments to strengthen sample sequencing to assess the spread of these emerging lineages.
In Hong Kong, the Department of Health issued a recommendation for high-risk populations to use surgical masks in enclosed public spaces. However, the same statement noted that there is no evidence that NB.1.8.1 causes more severe forms of COVID-19 than other variants in its family.
What do the CDC say about the current hospital situation in the US?
In their weekly update on May 23, the CDC reported that emergency room visits for COVID-19, seasonal flu (influenza), and respiratory syncytial virus (RSV) remain at low levels nationwide. According to the agency’s statistical model, this trend is expected to continue over the next two weeks.
Additionally, data from the National Wastewater Surveillance System indicate that most states have low or very low levels of viral circulation, with the sole exception of South Dakota, where a higher viral load has been observed in collected samples.
What is the currently dominant variant in the US?
The predominant variant in the United States as of May 10, 2025, is LP.8.1, also a descendant of JN.1, according to the CDC’s surveillance report cited by Reuters. This subvariant accounts for approximately 70% of nationally sequenced samples during the reference period.
Following this trend, the Food and Drug Administration (FDA) convened its independent advisory committee to evaluate the composition of COVID-19 vaccines for the 2025-2026 season. The FDA announced that it will require new clinical trials from manufacturers to approve booster vaccines for individuals under 65 without risk conditions, according to Reuters.
What does the WHO say about the circulation of these variants?
The World Health Organization (WHO) recently classified the additional public health risk associated with the LP.8.1 variant as low. In its technical bulletin of May 22, 2025, the organization stated that existing vaccines continue to be effective in reducing symptomatic and severe disease caused by this sublineage.
Although NB.1.8.1 has not yet been individually assessed by the WHO, its relationship with other JN.1 variants allows experts to anticipate similar clinical behavior. The WHO continues to promote genomic surveillance as a key tool for anticipating changes in the virus’s epidemiology.
Will vaccines change for the 2025-2026 season?
The FDA is evaluating reformulating booster vaccines to better target dominant sublineages of JN.1, such as LP.8.1. Regulators believe that the XBB.1.5 lineage, used in previous boosters, no longer reflects most circulating variants. The new vaccination scheme could be ready before fall 2025, depending on clinical trial results and regulatory approval.
Image: Infobae
