COVID-19: New variant NB.1.8.1 detected in travellers arriving US

A new COVID-19 strain, NB.1.8.1, which has been linked to an increase in hospitalisations in China, has now been detected in the United States, including among international travellers arriving in major cities such as New York and Washington.

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According to the US Centres for Disease Control and Prevention (CDC), the variant was first detected in the country between late March and early April 2025 through airport surveillance testing, CBS reports.

“CDC is aware of reported cases of COVID-19 NB.1.8.1 in China and is in regular contact with international partners,” a CDC spokesperson reportedly said in a statement.

The CDC stated that there are few reported cases for the variant to be fully captured in national estimates; however, experts have warned that NB.1.8.1 appears to spread faster than other recent strains of the virus.

What this means

NB.1.8.1 is a subvariant of Omicron JN.1 and is considered highly infectious. It has been designated a “variant under monitoring” by the World Health Organisation (WHO) due to its increasing global prevalence and potential to evade immunity from previous infections or vaccinations.

Recent WHO data shows the variant accounted for 10.7 per cent of sequenced COVID-19 cases globally between 21 and 27 April, an increase from 2.5 per cent the previous month.

While early findings suggest that the variant does not cause more severe illness than others, health authorities are monitoring it. Some reports indicate that symptoms include sore throat, fever, fatigue, muscle aches, nasal congestion, and, in some cases, gastrointestinal issues.

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Amy Edwards, a pediatric infectious disease expert at Case Western Reserve University, told CBS News there is some evidence in the lab that this variant binds more tightly to human cells, making it easier to transmit.

Ms Edwards noted that although the variant doesn’t appear more dangerous in terms of severity, “what they’re seeing in China, Hong Kong and some other areas where this variant has surged is an increase in hospitalisations.”

Global spread and detection

Beyond China and the US, NB.1.8.1 has been detected in countries such as Japan, South Korea, Vietnam, Thailand, Taiwan, France, Spain, and the Netherlands.

In Australia, genomic sequencing showed that the variant now accounts for over 40 per cent of COVID-19 cases in Victoria and has become the dominant strain in wastewater samples in Perth.

These developments have prompted renewed surveillance efforts in several countries. Officials in South Korea on Friday said its government is closely monitoring COVID-19 cases in China and Hong Kong.

Despite the surge, WHO has stated that NB.1.8.1 is not currently considered a greater public health risk than previously circulating variants. However, its ability to spread quickly remains a concern.

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Since the COVID-19 pandemic began in late 2019, the SARS-CoV-2 virus has continued to evolve, leading to the emergence of multiple variants. These include the original strain, followed by Alpha, Delta, and Omicron, each marked by different levels of severity, transmissibility, and vaccine resistance.

NB.1.8.1 is the latest from the Omicron lineage, which first appeared in late 2021 and became dominant worldwide due to its ability to spread rapidly.

No reported cases in Nigeria

As of the time of this report, Nigerian health authorities have not issued any formal guidelines or updates concerning NB.1.8.1.

The Nigeria Centre for Disease Control and Prevention (NCDC) has also not publicly acknowledged the variant or guided travel, testing, or potential local surveillance.

PREMIUM TIMES observed that the NCDC has been giving fewer COVID-19 updates since global cases and deaths declined.