The award-giving body says they 'contributed to the unprecedented rate of vaccine development during one of the greatest threats to human health in modern times'.

Australia closed its international borders and locked down cities among other restrictions that helped keep infections and deaths far below levels in other comparable developed economies such as the US and Britain.

The US Department of Health and Human Services also announces an investment of US$600 million in 12 domestic Covid-19 test manufacturers.

Covid infections and hospitalisations have been on the rise in the US, Europe and Asia but are well below previous peaks.

The US Food and Drug Administration approved the shots for those aged 12 and above, and authorised them for emergency use in children aged 6 months through 11 years.

The company has said its shot generated an 8.7-fold increase in neutralising antibodies in humans against BA.2.86, which is being tracked by the WHO and the CDC.

Scientists have said BA.2.86, an offshoot of the Omicron variant, is unlikely to cause a devastating wave of severe disease and death, given immune defences built up worldwide from vaccination and prior infection.

The vaccine is to be used for preventing Covid-19 in adults and children with a dosage dependent on previous vaccinations.

Those return will be put under medical observation at quarantine wards for a week.

China's decision to end the three-year zero-Covid policy led to a massive surge in hospitalisations and deaths that health experts say were largely unreported by the government.

The Omicron offshoot carries more than 35 mutations in key portions of the virus compared with XBB.1.5, the dominant variant through most of 2023.

A total of 119 defendants pleaded guilty or were convicted at trial during the sweep, according to the Justice Department.