Restrictions are being placed on New Year festivities around the world as many countries struggle to curb new spikes in coronavirus cases.
Fireworks displays and other public gatherings have been cancelled from Sydney to New York.
Festivities are being particularly muted in Europe, amid fears over a new more contagious strain of the disease.
France has mobilised 100,000 police to break up New Year's Eve parties and enforce a night-time curfew.
More than 1.8 million people have died with the virus across the world since the start of the pandemic a year ago. More than 81 million cases have been reported.
One of the first nations to ring in the New Year was Australia. The Sydney fireworks display went ahead, but crowds were not allowed to gather on the city's harbour to enjoy it.
"We don't want to create any super-spreading events on New Year's Eve," New South Wales premier Gladys Berejiklian said.
Many Sydney residents simply watched the pyrotechnics on TV at home, where gatherings are limited to five guests.
In China, the annual New Year light show in the capital Beijing was called off. Celebrations were scaled down in cities across the country. But in Wuhan, where the pandemic is thought to have originated, thousands of people gathered in the city centre to celebrate as balloons were released into the air.
Japan cancelled a traditional New Year event at which Emperor Naruhito and other imperial family members were to greet people.
In India, Delhi and several other cities imposed a night curfew and other restrictions to prevent large New Year gatherings.
However in New Zealand, where a strict lockdown and border closures have all but eliminated Covid, New Year celebrations were held as usual.
What about Europe?
In France, the government ordered a visible security presence in urban areas from 20:00 on Thursday, when the curfew begins. In Paris half of the metro lines will be closed in the evening.
France has had two lockdowns and bars, restaurants and cultural attractions will remain shut into the new year.
In England - where the new coronavirus strain is spreading fast and 20 million people in the worst-affected regions are forced to stay at home - UK Prime Minister Boris Johnson urged people to follow the rules.
"That means not meeting up with friends or family indoors, unless they're in the same household or support bubble, and avoiding large gatherings of any kind," he said on Wednesday.
The Metropolitan Police issued a warning to potential revellers in London to "celebrate the new year in the comfort of their own homes".
'We're happy the big night out is cancelled'
Ireland will move to its highest level of restrictions on Thursday, banning all household visits, closing all non-essential retail and limiting travel to 5km (three miles).
Germany is currently under lockdown until 10 January. The government has banned the sale of fireworks and placed tight restrictions on the number of people who can gather in public.
In what was expected to be her last New Year's Eve address as chancellor as she plans to step down in nine months, Angela Merkel took aim at conspiracy theorists.
Making a rare show of emotion, she said she could only imagine how cynical and cruel their dangerous lies must feel to those who had lost loved ones to the virus.
In Italy, a 22:00 curfew has been imposed, and bars, restaurants and most shops are closed. Meanwhile Pope Francis will not lead New Year's Eve and New Year's Day services in Rome after suffering a recurrence of chronic hip pain.
The Netherlands is also under a lockdown, which is set to last until 19 January. Its usual countdown will take place behind closed doors at a football stadium in Amsterdam.
Turkey will begin a four-day-long lockdown on New Year's Eve.
In the US officials have placed restrictions on festivities in many states and cities. In New York the illuminated Times Square Ball will be dropped during the traditional countdown to midnight, but the area will not be open to the public.
Fireworks have been cancelled in cities including San Francisco and Las Vegas.
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