COVID updates: Secretary of Defense Lloyd Austin tests positive
He said he has mild symptoms and will be quarantining for five days.
As the COVID-19 pandemic has swept the globe, more than 5.4 million people have died from the disease worldwide, including over 825,000 Americans, according to real-time data compiled by Johns Hopkins University's Center for Systems Science and Engineering.
About 62% of the population in the United States is fully vaccinated against COVID-19, according to data from the Centers for Disease Control and Prevention.
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Surge in omicron cases will 'get worse,' Fauci says
The surge in COVID-19 cases is "going to get worse before it gets better, that's for sure," Dr. Anthony Fauci said Monday on "Good Morning America."
And it could take weeks for the number of daily cases to start declining, he noted.
"It's very difficult to predict, because we have so many unvaccinated people in this country who are really quite vulnerable," Fauci said. "Even with the vaccinated people, you're going to see breakthrough infections."
Fauci also sought to ease concerns about the availability of at-home tests. Demand for those tests spiked during the holiday season, as worries about omicron grew and families took precautions before gathering.
"Well certainly omicron is a very, very unusual variant in its incredible degree of spreading," Fauci said. "As we enter January, there will be many, many more tests that we have."
Israel begins testing 4th vaccine dose
Medical staffers at Tel HaShomer hospital near Tel Aviv, Israel, have begun receiving a fourth COVID-19 vaccine dose.
About 150 staffers were taking part in the trial, which began on Monday morning. They'll be monitored for a week.
The Ministry of Health has yet to announce a final decision on a fourth jab. Prime Minister Naftali Bennett's office last week said on Twitter that it had instructed the government to "prepare for an extensive operation."
"This is wonderful news that will assist us in getting through the Omicron wave that is engulfing the world," Bennett said in a statement.
-ABC News' Bruno Nota
New York subway scales back service amid COVID surge
Subway trains in New York City will run less frequently than usual this week amid a spike in COVID-19 cases.
"Like everyone in New York, we've been affected by the COVID surge," New York City Transit Authority officials wrote on Twitter.
Officials said the subway was dealing with staff shortages and service would be scaled back until Thursday.
"We’re taking proactive steps to provide the best, most consistent service we can," officials said on Twitter. "That means you may wait a little longer for your train."
Australia records first omicron death, as daily cases top 10,000
A man in his 80s who died near Sydney, Australia, was the country's first known death linked to the omicron variant, health officials said on Monday.
"The man was a resident of the Uniting Lilian Wells aged care facility in North Parramatta, where he acquired his infection," New South Wales health officials said in a news release. "He had received two doses of a COVID-19 vaccine and had underlying health conditions."
The country’s new daily cases topped 10,000 on Sunday, local media reported on Monday.
In New South Wales, Australia's most populous state, new coronavirus infections dipped to 6,324 on Sunday, down from a record 6,394 new cases on Christmas Day, according to health officials.
UK, Italy, Greece report record new daily cases
The United Kingdom, Italy and Greece broke records on Wednesday for daily new COVID-19 cases, according to government health officials.
The Greek government reported a record increase for new cases for a third consecutive day with 28,828 new cases and 72 COVID-19-related deaths.
About 64.3% of the population is fully vaccinated and 26.5% have received a booster or third dose, according to the European Centre for Disease Prevention and Control.
Health Minister Thanos Plevris announced on Wednesday that new restrictions will go into effect on Jan. 3, but Greece's Kathimerini newspaper reported that the government has decided to put them into effect at 6 p.m. local time on Thursday.
Italian health authorities recorded another record increase on Wednesday with 98,0303 new COVID-19 cases and 148 deaths.
Semi-official ANSA reported Wednesday's positivity rate is 9.5% and there are 1,185 patients in ICUs. About 51.7% of Italy's residents are fully vaccinated and 24.9% have received a booster or 3rd dose, per the ECDC.
UK health officials recorded 183,037 new cases and 57 deaths. The record-setting new case number included five days of data from Northern Ireland, which last published data on Dec. 24, according to health officials.
About 82.3% of adults in the UK have received two vaccine doses and 57.5% have received a booster, according to government data.
-ABC News' Christine Theodorou