The world ushered in 2022 with scaled-back celebrations due to new restrictions aimed at slowing soaring Covid cases - although hope remained for a better new year.

New York revived its New Year's Eve ball drop in Times Square in limited form, Paris dropped its fireworks show over rising Omicron cases and London's pyrotechnic display was broadcast on television.

More than 5.4 million people have died since the coronavirus was first reported in central China in December 2019.

Countless more have been sickened or subjected to outbreaks, lockdowns and a slew of virus tests.

The year 2021 started with hope as life-saving vaccines were rolled out to around 60% of the world's population, although many of its poor still have limited access.

As the year drew to a close, the emergence of the Omicron variant pushed the number of daily new Covid-19 cases past one million for the first time, according to an AFP tally.

France has become the latest country to announce Omicron was now its dominant coronavirus strain.

In Britain, the United States and even Australia - long a refuge from the pandemic - the variant's prominence is driving record new cases.

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New York brought back to life its annual New Year's Eve ball drop in Times Square after skipping the event last year over rising virus cases.

But the scaled-down event welcomed fewer revellers than in previous years, with about 15,000 people - all required to show proof of vaccination - allowed in.

Elsewhere, from Seoul to San Francisco, celebrations were again cancelled or curtailed in the face of the infection surge.

In Madrid's Puerta del Sol about 7,000 people - half the usual capacity - rang in the new year by eating grapes, one for each time the clock chimed up to 12.

Dubai went ahead with its celebrations undeterred, with 36 firework displays at 29 locations.

But authorities warned they would fine anyone in attendance not wearing a mask.

Police officers patrolled the Champs-Elysees in Paris, which was lit with glittering red lights and festooned with "2022" balloons, also on the lookout for people without masks.

Most people were simply asked to wear one, but some who argued were fined.

In Sydney, which normally bills itself as the "New Year's Eve capital of the world", the vast harbour where people gathered to watch the city's fireworks was notably uncrowded.

With tourists still unable to enter the country and many residents fearful of the rapid spread of Omicron, tens of thousands were estimated to have attended, rather than the usual one million-plus.

Still, the city saw New Year's Eve in with a bang - igniting six tonnes of technicolored fireworks that lit up the Opera House and floating barges.

In Tunis, authorities cited a "rise in cases" of coronavirus for the last-minute cancellation of festivities.

In contrast, South Africa - the first country to report Omicron back in November - lifted a curfew late Thursday to allow festivities to go ahead.

In Rio, celebrations on Copacabana Beach went ahead in a scaled-back format, although crowds still arrived at the traditional party spot.

After last year's festivities were cancelled due to Covid, it was a comparatively muted return for Rio.

A ban on musical performances, traffic and public transport made for a more muted atmosphere on the city's famed beach.

In Mexico City, authorities cancelled a number of planned mass outdoor events, including a music concert on one of the capital's main boulevards, following an increase in coronavirus cases.

The World Health Organization has warned of trying times ahead, saying Omicron could lead to "a tsunami of cases".

Many Western leaders have been hesitant to reimpose the strict controls seen in 2020, for fear of sparking a new economic downturn.

But on-again-off-again restrictions have still prompted frequent, vocal and occasionally violent anti-lockdown, anti-vaccine and anti-government protests.

US President Joe Biden urged unity for the new year in a video message, during which he also praised "extraordinary" Americans.