A new Covid-19 variant, dubbed NB.1.8.1, has raised alarms among health experts after being detected in multiple U.S. states.

According to reports from the Daily Mail, this strain, believed to have originated in China, has been identified among international travelers arriving in California, Washington, Virginia, New York City, Hawaii, Rhode Island, and Ohio.

The variant’s emergence comes amid a surge in hospitalizations in China, prompting warnings about its potential to spread more rapidly than existing strains.

The U.S. Centers for Disease Control and Prevention (CDC), as cited by CBS News and reported by the Daily Mail, confirmed that NB.1.8.1 was detected through the CDC’s airport testing program, managed by Ginkgo Bioworks.

Between April 22 and May 12, 2025, travelers arriving from nine countries—China, Japan, Vietnam, South Korea, Taiwan, Thailand, France, the Netherlands, and Spain—tested positive for the variant.

Despite its presence in the U.S. since late March, there has been no significant uptick in overall Covid-19 cases, with the positivity rate of swabs detecting the virus dropping by 12% in the latest week of available data.

This suggests that while NB.1.8.1 is circulating, it has not yet driven a major wave of infections in the U.S.

Early research from China indicates that NB.1.8.1 may be more infectious than current dominant strains due to its enhanced ability to bind to human cells.

In China, the proportion of severely ill respiratory patients with Covid-19 has risen from 3.3% to 6.3% over the past month, signaling a potential increase in the variant’s severity.

This has led to heightened vigilance, with Hong Kong officials urging high-risk individuals to wear face masks in public spaces and crowded areas like public transportation.

The U.S. Food and Drug Administration (FDA) also discussed the strain during a recent meeting on updating Covid-19 vaccines, which currently target the JN.1 variant and its descendants.

However, the alarm surrounding NB.1.8.1 may be tempered by the lack of evidence suggesting it evades immunity more effectively than other variants.

The Daily Mail notes that while the strain appears more transmissible, it does not seem to bypass the immune system significantly better than existing variants.

This raises questions about whether the concern is proportionate to the current data, especially given the absence of a sharp rise in U.S. cases.