Omicron updates: COVID-19 cases could double in New York City

The omicron variant appears to be "dominating" new infections in most of South Africa's provinces, South African President Cyril Ramaphosa said in a newsletter Monday.

Ramaphosa said the number of daily cases has increased five-fold in the last week.

"As the country heads into a fourth wave of COVID-19 infections, we are experiencing a rate of infections that we have not seen since the pandemic started," he warned.

Just 24.41% of South Africa's population is fully vaccinated, according to Africa CDC. Ramaphosa said scientists in South Africa and around the world are working to answer critical questions about the new variant, and the urgent priority is to continue getting people vaccinated. 

-ABC News' Christine Theodorou

Italy's Super Green Pass -- which certifies a person is fully vaccinated or has recovered from COVID-19 -- is now required inside restaurants as well as sports and cultural events.

The Super Green Pass goes into effect Monday and will last at least through Jan. 15, 2022.

COVID-19 cases in Italy have increased by 57% over the two weeks, according to the World Health Organization.

-ABC News' Phoebe Natanson

New York City Mayor Bill de Blasio on Monday announced a vaccine mandate for all private sector employees.

On the talk show "Morning Joe," the mayor called the mandate, which goes into effective Dec. 27, a "preemptive strike."

New York City will also now mandate two vaccine doses, instead of one, for indoor activities, and will require proof of vaccination for indoor dining for kids ages 5 to 11.

Peter McGinn was one of the first known people in the United States to contract the omicron variant.

The 30-year-old Minnesota resident, who is fully vaccinated against COVID-19 and has received a booster shot, said he believes he became infected after attending a massive anime convention in New York City in late November. McGinn said he and several other attendees, who are also fully vaccinated, went out together after the event. Half of that group has since tested positive for COVID-19, according to McGinn.

McGinn said he tested positive after returning home to Minnesota and learning that a friend with whom he attended the convention had contracted the virus.

"I felt perfectly safe with the people that I was with, and so it never really crossed my mind to think that I had COVID," McGinn told ABC News on Sunday. "I was just a little taken aback."

Several dozen cases of omicron, a newly discovered variant of the novel coronavirus, have now been reported in at least 17 states across the country, according to Dr. Rochelle Walensky, director for the Centers for Disease Control and Prevention.

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Health officials on alert as omicron variant spreads

The emerging variant has now been reported in at least 17 U.S. states, as demand for COVID-19 vaccine shots rises and officials stress the importance of getting boosters.

ABCNews.com