Australians are being cautioned about the potential threat posed by falling Covid-19 vaccination rates amid the emergence of a new, highly contagious variant.

The subvariant NB.1.8.1—first identified on January 21—is now driving a surge in Covid-19 cases across China, Hong Kong, and Taiwan. It has also become the dominant strain in Western Australia, contributing to a 24% increase in case numbers.

Professor Paul Griffin, infectious diseases expert at Mater Hospital in Brisbane, noted that current Covid vaccination rates are at their lowest since vaccines were first introduced five years ago.

“We’ve lost momentum with Covid-19 vaccinations,” said Prof Griffin. “But the virus remains widespread and continues to pose a significant risk, especially to high-risk individuals.”

He recommends an annual Covid booster for vulnerable populations, similar to the seasonal flu shot. “With winter beginning next week, now is the time to get vaccinated—and it’s safe to receive the Covid and flu vaccines together,” he said.

NB.1.8.1 is one of hundreds of Omicron subvariants and is contributing to rising infections and hospitalisations, especially in Asia and Western Australia.