A new and highly transmissible variant of the coronavirus, known as NB.1.8.1, has been detected in California and several other U.S. states, prompting concern among public health experts as the federal government moves to restrict access to updated COVID-19 vaccines.

First identified as a driving force behind a major surge in cases across China, the NB.1.8.1 variant has been reported in international travelers screened at airports in Washington, Virginia, New York and California. ...

Experts said they were closely monitoring the variant, which is spreading rapidly across parts of Asia and Europe. In Hong Kong, health officials recently reported the highest levels of COVID-19 activity in at least a year, citing a “significant increase” in emergency room visits and hospitalizations.

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