The Covid-battered United States authorised Johnson & Johnson's vaccine for emergency use Saturday, offering a glimmer of hope, as schools, colleges in India's Pune city have been ordered to remain shut till March 14 due to surge in virus cases.

Exactly a year after New Zealand recorded its first coronavirus case, the biggest city of Auckland yesterday woke to a second lockdown this month, as authorities try to rein in a cluster of the more contagious UK variant.

The seven-day lockdown of a population of nearly 2 million, announced late on Saturday by Prime Minister Jacinda Ardern, was prompted by the case of a person who had been infectious for a week but not in isolation.

US President Joe Biden hailed his country's announcement of its third available vaccine but said the nation's battle was far from over.

"This is exciting news for all Americans, and an encouraging development in our efforts to bring an end to the crisis," Biden said in a statement, but warned Americans "cannot let our guard down now or assume that victory is inevitable."