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.
Fauci recommends against big New Year's parties
Dr. Anthony Fauci strongly recommended against large New Year's Eve parties at Wednesday's White House briefing.
"Should you change or cancel your plans? If your plans are to go to a 40-50 person New Year's Eve party with all the bells and whistles and everybody hugging and kissing and wishing each other a happy new year, I would strongly recommend that this year, we do not do that," Fauci said.
Fauci said "all indications point to a lesser severity of omicron versus delta." But he warned, "we should not become complacent since our hospital system could still be stressed in certain areas."
White House COVID-19 coordinator Jeff Zients said, "We have directly helped more than 30 states and territories by deploying over 2,100 federal personnel and thousands of ambulances, ventilators and other critical supplies."
Supplies include gloves, masks, respirators and face shields, he said.
He added, "More than 13,000 National Guard members have been activated in 48 states to support the COVID response, from vaccinations, to testing, to clinical care."
At the briefing, CDC Director Rochelle Walensky defended the agency's shortened isolation guidelines.
"We do know the vast majority of viral transmission happens in those first five days, somewhere in the 85 to 90% range. So if a person can isolate for the first five days they absolutely should," she said. "We also don't know that antigen tests give a good indication of transmissibility at this stage of infection. On the other hand, we know that after five days people are much less likely to transmit the virus and that masking further reduces that risk. And this is why people need to mask for five days after the five days of isolation."
After five days, asymptomatic people with COVID-19 can leave isolation, but must wear masks around others, according to the new guidelines.
-ABC News' Cheyenne Haslett