A new and apparently more infectious variant of Covid-19 has been detected in the US after cases surged in China.
The strain called NB.1.8.1 has been found in international travellers at a number of US airports, data from the country’s Centre for Disease Control and Prevention (CDC) shows.
New reports of the strain have now also been picked up separate to the airport cases, indicating it could now be spreading locally.
NB.1.8.1 has contributed to a new wave of Covid cases in parts of Asia.
The number of severely ill respiratory patients with Covid in China has risen from 3.3 to 6.3% in the last month.
The proportion of A&E patients testing positive for Covid in Chinese hospitals has also spiked from 7.5 to 16.2%.
There has also been a 78% surge in Covid hospital admissions in Taiwan.
After Covid hospitalisations in Hong Kong reached a 12 month high, people are now being urged there to wear face masks again on public transport or in crowded places.
There is no evidence that the virus is more severe, according to the World Health Organisation (WHO), and the variant is not better at evading the immune system compared to other strains.
However NB.1.8.1 does have a greater ability to bind to human cells.
This suggests the strain could be more transmissible.
The new Covid cases picked up in the US originated from people coming from nine countries: China, Japan, Vietnam, South Korea, Taiwan, Thailand, France, the Netherlands and Spain.
They were tested between April 22 and May 12 through a scheme whereby travellers at airports can volunteer to have nasal swabs taken.
Health authorities have now reported unrelated cases of the variant in Ohio, Rhode Island and Hawaii.
There are also cases in California and Washington states which date back as early as late March and early April.
Despite the new cases there is no surge in positive testing in the US.
The number of test swabs detecting the Covid actually fell 12% in the latest week data is available.
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