Here's what you need to know about the coronavirus right now:

U.S. deaths top 250,000

The U.S. death toll from COVID-19 surpassed a grim new milestone of 250,000 lives lost on Wednesday, as New York City's public school system, the nation's largest, called a halt to in-classroom instruction, citing a jump in infection rates.

The decision to shutter schools and revert exclusively to at-home learning, starting on Thursday, came as state and local officials nationwide imposed restrictions on social and economic life to tamp down a surge in cases and hospitalizations heading into winter.

Governor Tim Walz of Minnesota ordered all restaurants, bars, fitness centers and entertainment venues closed, and all youth sports canceled, for four weeks.

WHO warns of a tough six months

Fresh lockdowns in Europe are avoidable, including through near-universal mask-wearing, the head of the World Health Organization Europe office said on Thursday.

Hans Kluge said that some health systems are being overwhelmed on the continent where more than 29,000 deaths were recorded in the past week alone.

"Europe is once again the epicentre of the pandemic, together with the United States. There is light at the end of the tunnel but it will be six tough months," Kluge told a news conference.

Tokyo raises alert level to highest

Tokyo raised its coronavirus alert to the highest level on Thursday as its daily tally of new infections rose to a record 534 and its governor called for maximum caution as the year-end party season approaches.

Japan's nationwide tally also hit a new high of 2,259, according to broadcaster TBS.

"The number of coronavirus cases is rising so we are considering what steps will be needed with the view that infections could reach 1,000 cases a day," said Tokyo Governor Yuriko Koike.

Cases in Russia surpass 2 million

Russia's COVID-19 case tally passed the 2 million mark on Thursday as the number of daily deaths and infections hit new highs.

Russia, which has a huge testing programme and a population of around 145 million, has the world's fifth largest number of cases after the United States, India, Brazil and France.

Despite a recent surge in cases, authorities have resisted imposing lockdown restrictions across the country as they did earlier this year.

AstraZeneca vaccine shows promise in elderly

AstraZeneca and Oxford University's potential vaccine produced a strong immune response in older adults, data published on Thursday showed, with researchers expecting to release late-stage trial results by Christmas.

The data, reported in part last month but published in full in The Lancet medical journal on Thursday, suggest that those aged over 70, who are at higher risk of serious illness and death from COVID-19, could build robust immunity.

"We hope that this means our vaccine will help to protect some of the most vulnerable people in society, but further research will be needed before we can be sure," said Maheshi Ramasamy, a consultant and co-lead investigator at the Oxford Vaccine Group.