The US government's chief medical officer Dr Anthony Fauci has called on Americans to get vaccinated, as densely populated areas such as New York City have seen a surge in cases, and some European countries have reintroduced stricter restrictions.

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According to data from the World Health Organisation (WHO), the UK has reported the highest number of COVID-19 cases in Europe and the second highest in the world - 436,870 - in the last seven days.

Here's what the COVID situation looks like around the world.

United States

The first Omicron case was detected in the US on 1 December and since then numbers have increased by 40%.

Several large events have been cancelled or postponed, with three NFL matches delayed after outbreaks. The National Hockey League was also forces to cancel games, while performances of the Michael Jackson musical on Broadway have been called off.

Dr Tom Frieden, the former chief of the Centers of Disease Control and Prevention, has urged people to get their booster jabs, warning of a "tidal wave of Omicron likely coming to a hospital near you soon".

Despite the surge in cases, lockdowns of workplaces and social gatherings have not been put in place.

According to WHO data, the US has seen almost 800,000 COVID-related deaths since the pandemic began.

In the past seven days, some 571,461 cases were reported, the highest in the world in the last week.

The total number of coronavirus cases is now almost 50 million in the United States.

Germany

Germany is introducing new measures to curb the spread of COVID-19, limiting private gatherings among the vaccinated to a maximum of 10 people before New Year's Eve.

Chancellor Olaf Scholz also agreed with the premiers of Germany's 16 federal states that big events, including football matches, would take place without fans.

It is hoped the measures will encourage people to get vaccinated, as a fifth wave of coronavirus threatens the country.

"It is only a matter of weeks before Omicron is dominant here," Mr Scholz said.

The chancellor also confirmed that nightclubs and discos would remain closed and major national events will be held without an audience.

Germany is among several European countries that have introduced tougher measures for UK travellers.

As of midnight on Monday 20 December, people travelling from the UK to Germany have to quarantine and provide a negative coronavirus test under the new rules.

Spain

British tourists can only enter Spain if they show proof of a COVID-19 vaccination.

Until recently, unvaccinated travellers were allowed into the country if they could present a negative PCR test taken 72 hours before their arrival.

"The appearance of new variants... obliges an increase in restrictions," the government has said.

Spain's Industry, Trade and Tourism department said approximately 300,000 British people who are resident in Spain will not be affected by the new measures.

In football, Real Madrid's unbeaten record in La Liga ended on Sunday with a 0-0 draw against strugglers Cadiz - the team had been without six players due to a COVID-19 outbreak at the club.

According to WHO data, some 143,400 cases and 195 deaths have been reported in Spain in the last seven days.

France

On 16 December, France banned British tourists because of the rise in Omicron cases in the UK.

Those with a "compelling reason" are still able to travel but have to register the address of their stay in France.

Government spokesman Gabriel Attal told BFM television that restriction measures include reducing the validity of pre-departure PCR tests to 24 hours from 48 for travellers arriving from Britain.

The Delta variant remains dominant in France, which has recorded 350,382 total coronavirus cases and 973 deaths in the past seven days.

On Wednesday the country's health minister, Olivier Veran, said it could soon see 100,000 new cases a day but that the government did not plan on introducing new restrictions at this time.

"The objective is not to reduce the speed of the virus' spread because the variant is too contagious. The objective is to limit the risk of serious cases overwhelming hospitals," Mr Veran told BFM TV.

Portugal

Officials in Portugal have not introduced any new COVID-19 measures yet, despite the rise of Omicron.

Almost 30,000 total cases and 107 deaths were reported in the country in the last week.

South Africa

South Africa has reported the highest number of cases in Africa in the last seven days and the fifth highest globally.

There were 162,364 new infections in the last week, almost a month since the first Omicron case was reported there.

On 20 December, President Cyril Ramaphosa returned to work following a week of isolation after testing positive for COVID-19.

He had mild symptoms and was treated at his official residence in Cape Town by the military health service.

Despite a surge in cases in the last month, hospitalisations remain low with experts stating that vaccines and natural immunity are protecting people from more severe symptoms.

Mr Ramaphosa previously said South Africa would not impose new restrictions, but would "undertake broad consultations on making vaccination mandatory for specific activities and locations".

Current regulations in South Africa make it mandatory to wear face coverings in public and restrict indoor gatherings to 750 people and outdoor gatherings to 2,000.

The Netherlands

On 28 November, Dutch health officials detected 13 Omicron cases among people who flew from South Africa - making the Netherlands the first European country to report cases of the new variant.

The country entered into a tough lockdown to curb the spread of Omicron on Sunday 19 December, with non-essential shops, bars, restaurants and other public places closing, as well as schools.

The "unavoidable" lockdown will run until at least 14 January, Prime Minister Mark Rutte has said.

Shops, bars, and restaurants in the country had already been under a 5pm to 5am curfew, which was introduced at the end of November.

A total of 108,521 COVID-19 cases and 391 deaths have been reported in the Netherlands in the past week.

Italy

Prime Minister Mario Draghi said on Wednesday that the government was preparing new measures to tackle a surge in infections, following tougher rules. introduced for unvaccinated Italians on 6 December.

Mr Draghi said that obligatory mask-wearing outdoors and the use of the more protective FPF2 masks in some enclosed places were being considered, as were vaccine mandates.

Previously the country introduced a "super green pass" requiring vaccination, rather than a recent negative test result, to enter public events including sports events, concerts, theatres, and indoor restaurants.

The previously introduced "green pass", which can be obtained with a negative test result, will be acceptable for the use of local transport and hotels.

In the past seven days, Italy has recorded some 143,400 cases and 750 deaths.

Finland

Finland recorded approximately 13,400 new cases last week.

The government has introduced new restrictions to tackle rising infections and the Omicron variant, starting on Christmas Eve, meaning bars will stop serving alcohol at 9am and close at 10pm.

From December 28 onwards alcohol can only be served until 5pm with bars being restricted to 50% capacity and needing to close by 6pm, while restaurants will be restricted to 75% capacity and must close by 8pm.

More than 83% of the population aged 12 and over in Finland has received two vaccine doses.

Australia

Compared to cases globally, Australia has one of the lowest rates of new COVID-19 cases reported in the last seven days - 15,057 - with a similar number of cases as Iran and Colombia.

Earlier this year, England's Ashes tour was at risk because of rising cases in key Australian cities, including Sydney and Melbourne but tough restrictions for much of their winter has seen a dip in infections.

But, behind the numbers, there are concerns of a spike because of the Omicron variant.

According to reports, 10 testing sites in Melbourne were shut after reaching capacity, while there were long waiting times at centres in Victoria, New South Wales and South Australia.

Prime Minister Scott Morrison announced on Monday that he would discuss the Omicron outbreak with premiers at a snap national cabinet meeting on Friday.

New Zealand

As has been the case for most of the pandemic, New Zealand has managed to keep infections low.

In the latest seven-day period, there were 600 positive COVID-19 cases, bringing the total number of cases to 12,947.

COVID-19 response minister Chris Hipkins announced in November that fully vaccinated international travellers will be allowed into the country from 2022.

The border will first open to citizens and residents travelling from Australia on 16 January, before expanding to include New Zealanders living elsewhere on 13 February.

Fully vaccinated visitors from all other countries, except those deemed "high risk," can visit the country from 30 April, Mr Hipkins said.

Thailand

Since the pandemic began the Thai economy has been devastated as it relies heavily on tourism.

The government lifted restrictions to tourists in November, but it reported its first Omicron case on 20 December and is now considering reinstating some restrictions.

This includes the return of mandatory quarantine for foreign visitors.

In the last seven days, there were 24,717 new infections in Thailand.

Japan

Japan on Wednesday confirmed its first known local transmission of the Omicron variant, with the 80 or so previous cases all linked to people who had tested positive at airports.

Prime Minister Fumio Kishida said on Tuesday that he plans to keep the country's border controls, among the world's most stringent, in place until more details about the Omicron variant are known.

Mr Kishida said the government would be tightening quarantine rules for those who are in close contact with Omicron patients, requiring 14 days of isolation at designated facilities instead of the previous self-isolation at home.

South Korea

There are currently a record 1,063 patients with COVID-19 in a serious or critical condition in South Korea, where Delta remains the most dominant variant.

The country recently reimposed its toughest social distancing rules to try to control a record-breaking surge of infections.

There are only 234 cases of the Omicron variant in South Korea as of Wednesday, but health officials expect it to become the dominant strain within a few months.

South Korea's restored restrictions include a ban on private gatherings of five or more people, a 9pm curfew for restaurants, coffee shops and karaoke venues, and required proof of vaccination for entry to restaurants and other businesses.

Singapore

Singapore has confirmed 65 imported Omicron cases and a handful of local ones, although the government says it has been able to prevent onward transmission.

The country is freezing the sale of tickets for arriving flights and buses that had been available under its quarantine-free travel programme.

About two dozen counties, including the United Kingdom, were allowed quarantine-free entry for fully vaccinated travellers, but this scheme will be paused until 20 January, said the government.

In a statement the Health Ministry said: "Our border measures will help to buy us time to study and understand the Omicron variant, and to strengthen our defences, including enhancing our healthcare capacity, and getting more people vaccinated and boosted."