COVID updates: Secretary of Defense Lloyd Austin tests positive

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

Dr. Anthony Fauci appeared on ABC News Live Wednesday and shared his thoughts on the U.S. Centers for Disease Control and Prevention's decision to lower its recommended isolation period to five days for asymptomatic patients.

Fauci also said that while new evidence shows  omicron may be less severe than delta, people should still be cautious of contracting and spreading the virus.

"You can get people safely back out in a five day period so long as they wear a mask, if they are without symptoms. That is the science," he told ABC News Live. "The impact of that is to try and not be in a situation where we essentially have to shut down the entire country."

Fauci also said it would be too premature to be less worried based on evidence that omicron may be less severe.

"We are heartened by the fact that from the South African data, the data from the U.K., and the accumulating data in the United States that it looks like it is less severe," he said. "It's much more transmissible, which is something you need to take seriously."

The U.S. Food and Drug Administration gave emergency use authorization to two over-the-counter COVID-19 tests.

The tests are manufactured by SD Biosensor and Siemens.

"Combined, it is estimated the companies can produce tens of millions of tests per month for use in the U.S.," the U.S. Department of Health and Human Services said in a statement.

-ABC News' Sony Salzman

The U.S. reported more than 1.9 million new cases this week, which equals about three Americans testing positive for COVID-19 every second. 

The U.S. is now averaging 277,000 new cases each day, shattering the previous record average from Jan. 11, 2021, which was 250,000 cases each day, according to federal data. 

Although this significantly high number is in large part due to the latest surge, it’s also attributable to the soaring demand for tests and backlogs of data following Christmas weekend. 

-ABC News' Arielle Mitropoulos