Omicron variant sweeping across nation, now accounts for 73% of new cases; Moderna 3rd dose effective vs. omicron: COVID-19 updates

Omicron has raced ahead of other variants and is now the dominant version of the coronavirus in the U.S., accounting for 73% of new infections last week, federal health officials said Monday.

The Centers for Disease Control and Prevention numbers showed nearly a six-fold increase in omicron's share of infections in only one week.

Overall, omicron is still a small percentage of all U.S. COVID cases. In the week that ended Dec. 11, omicron’s share of new infections in the U.S. increased to 2.9% from 0.4% the week before, the CDC previously reported.

But CDC said they are revising some of the earlier numbers, after analyzing more specimens. The new numbers indicate that about 13% of the infections the week of Dec. 11 were omicron, and not 3%, CDC officials said.

THE LATEST ON COVID: Biden to reveal plan to help hospitals 

In much of the country, omicron's prevalence is even higher. It's responsible for an estimated 90% of new infections in the New York area, the Southeast, the industrial Midwest and the Pacific Northwest.

Since the end of June, the delta variant has been the main version causing U.S. infections. As recently as the end of November, more than 99.5% of coronaviruses were delta, according to CDC data.

Scientists in Africa first sounded the alarm about omicron less than a month ago and on Nov. 26 the World Health Organization designated it as a “variant of concern." The mutant has since shown up in about 90 countries.

Much about the omicron variant remains unknown, including whether it causes more or less severe illness. Early studies suggest the vaccinated will need a booster shot for the best chance at preventing omicron infection but even without the extra dose, vaccination still should offer strong protection against severe illness and death.

“All of us have a date with omicron,” said Dr. Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security. “If you’re going to interact with society, if you’re going to have any type of life, omicron will be something you encounter, and the best way you can encounter this is to be fully vaccinated.”

Also in the news:

►The United States has reported more than 51 million COVID-19 cases, Johns Hopkins University data showed late Monday. Also on Monday, Kansas became the 32nd state to report at least 500,000 cases. And the world has reported more than 275 million cases.

►Washington, D.C., Mayor Muriel Bowser declared a state of emergency and reinstated an indoor mask order lifted a month ago. The mandate goes into effect at 6 a.m. ET Tuesday and runs through January. The city is facing its highest daily infection totals since the pandemic began.

►Idaho health officials on Monday deactivated crisis guidelines for rationing care at medical facilities in northern Idaho. A decline in new infections was cited.

►The New Year’s Eve party planned for downtown Los Angeles’ Grand Park will not have an in-person audience because of the rising number of coronavirus cases, organizers said. The “NYELA Countdown to 2022” event will be streamed, as it was last year.

►Boston Mayor Michelle Wu said that starting Jan. 15, patrons of indoor dining, bars, nightclubs and gyms must show proof of at least one vaccine dose. Proof of full vaccination will be required for adults Feb. 15, and city workers must get vaccinated, she said at a City Hall news conference as protesters shouted “Shame on Wu.”

►Maryland Gov. Larry Hogan said he received a positive coronavirus rapid test Monday. "I have been vaccinated and boosted, and I am feeling fine at the moment," Hogan tweeted. He also urged Marylanders to get vaccinated and/or boosted.

📈Today's numbers: The U.S. has recorded more than 51 million confirmed COVID-19 cases and more than 807,000 deaths, according to Johns Hopkins University data. Global totals: More than 275.2 million cases and 5.3 million deaths. More than 203.9 million Americans – 61.4% of the population – are fully vaccinated, according to the CDC.

📘What we're reading: A study by Oregon researchers finds that people fully vaccinated against COVID-19 who have breakthrough infections end up with what the authors call "super immunity." They caution the vaccinated should not seek COVID-19 infection, but the "hybrid immunity" offers some solace for those who catch one despite having been vaccinated. 

Keep refreshing this page for the latest news. Want more? Sign up for USA TODAY's free Coronavirus Watch newsletter to receive updates directly to your inbox and join our Facebook group.

Biden aide tests positive for COVID-19 after flying with president

A White House aide who was in close contact with President Joe Biden aboard Air Force One on Friday tested positive for COVID-19 on Monday, White House press secretary Jen Psaki said in a statement Monday evening.

Biden tested negative Sunday and Monday and is scheduled for a re-test again Wednesday. He is not changing his daily schedule because the CDC does not require fully vaccinated people to quarantine after an exposure, Psaki said. 

The aide, a “mid-level staff member” who was fully vaccinated, spent about 30 minutes “in proximity to the president” as Biden flew from South Carolina to Pennsylvania on Friday, according to the White House statement. The White House did not identify the aide by name.

- Maureen Groppe

Moderna booster is effective against omicron

The first data available for Moderna’s COVID-19 vaccine suggests a third booster dose will be effective against omicron, the variant that is rapidly taking over the world.

The encouraging revelation came hours before former President Donald Trump said he has received a coronavirus booster shot. Trump was appearing on Bill O'Reilly's "History Tour" at the American Airlines Center in Dallas when the host asked if he was boosted. "Yes," Trump replied to a smattering of boos.

Public health officials have been urging Americans to get booster shots. Moderna said early Monday that in a lab study, blood from 20 people who received the 50-microgram Moderna booster had 37 times the number of neutralizing antibodies as compared to blood from the same number of people who only received two shots. Moderna had reduced the dose of its booster to half the dose of the original two shots to limit side effects such as fever, muscle aches and fatigue.

A group that received a third shot of the higher, 100-microgram dose saw an 83-fold jump in neutralizing antibodies against omicron. Dr. Eric Topol, founder and director of the Scripps Research Translational Institute, said such a big increase isn’t necessary to provide protection.

A study released earlier this month by Pfizer and its partner BioNTech showed that a third dose of their COVID-19 vaccine boosted neutralizing antibodies against omicron more than 25-fold, which should be protective, Topol said, though real-world studies are needed to prove it.

“I think it’s pretty encouraging,” he said. “We’ll take any positive we can get.”

Omicron now 82% of Houston Methodist's new symptomatic cases

The Houston Methodist hospital system reports that the omicron variant accounts for 82% of new symptomatic cases it is treating. Dr. S. Wesley Long, medical director of diagnostic microbiology, said the omicron variant is now in Houston “in full force.” The omicron variant became the “cause of the supermajority” of new Houston Methodist cases in less than three weeks, he said. In comparison, the delta variant took three months during the summer before it was the cause of more than 80% of cases.

"Omicron in our data has a doubling time of 2.2 days," Long tweeted.

'Someone's got to do it': Vaccines tested in kids under 5 years old

There are no authorized COVID-19 vaccines in the U.S. for children younger than 5 years old. But kids like Dr. Alicia Carrasco’s 1-year-old twins and 3-year-old son Matías are participating in Moderna’s trial and are helping to change that. The twins received their second jab a few weeks ago, and Matías is scheduled to get his next shot in a few weeks. Velocity Clinical Research, a clinical trial site organization, enrolled about 650 children at four locations across the country. A quarter of the children received the placebo and the rest were vaccinated with Moderna’s vaccine. No one knows for certain which they were given, but the internal medicine physician is confident the sudden fever she saw in the twins is a sign they were jabbed with the active vaccine.

“Someone’s got to do it," she said. "My kids are the most important thing in the world to me but so is anyone else’s kids who have been a part of trials.” Read more here.

– Adrianna Rodriguez

New infections up 41% from a month ago

The U.S. is moving toward Christmas in dramatically different shape than it was before Thanksgiving. A month ago, case counts had been rising, to about 90,000 per day on average. For much of December cases appeared to hover around 120,000 but have recently leaped above 130,000 per day, Johns Hopkins data shows. Compared to a month ago, the pace of new cases nationally is up 41%.

Overall, the CDC says about three-quarters of counties have high levels of transmission. But where you live is important. The pace of cases is up 393% in Hawaii, more than tripled in Connecticut and New Jersey, and more than doubled in Delaware, Florida, Illinois, Massachusetts, New York and Rhode Island. But cases appear to have fallen in at least a third of the states – down 72% in Montana, 61% in Wyoming, 58% in Alaska, 46% in Colorado.

– Mike Stucka

New Zealand man dies from myocarditis linked to Pfizer vaccine

A 26-year-old man has died from myocarditis linked to the Pfizer vaccine, health officials in New Zealand said Monday.

Myocarditis, a form of heart inflammation, has been detected in a small number of vaccinated individuals. It is treatable, is not specific to COVID-19 vaccines, and was a common side effect of the smallpox vaccine in the past, according to the U.S. Centers for Disease Control and Prevention. 

The man died within two weeks of receiving his first dose, and a coroner determined that preliminary information has identified myocarditis as the probable cause of death, New Zealand's COVID-19 Vaccine Independent Safety Monitoring Board said in a statement.

"With the current available information, the board has considered that the myocarditis was probably due to vaccination in this individual," the monitoring board's statement said.

The statement said the benefits of vaccination with the Pfizer vaccine continue to "greatly outweigh" the risk of such rare side effects, adding that the COVID-19 infection can itself be a cause of myocarditis as well as other serious illnesses.

More on myocarditis:

• Kids getting sick with COVID-19 is far riskier than rare side effect myocarditis, experts say
• Rate of myocarditis slightly higher in young people after COVID vaccine, CDC finds

Dozens on cruise ship test positive

At least 48 people on board Royal Caribbean's Symphony of the Seas ship that ended a seven-day cruise in Miami on Saturday were positive for COVID-19 during the sailing, the cruise line said. Those 48 people who tested positive represented less than 1% of the 6,074 passengers and crew members on board Symphony of the Seas, which left Miami on Dec. 11 and made stops in St. Maarten, St. Thomas, and Perfect Day at CocoCay (Royal Caribbean's private island), spokesperson Lyan Sierra-Caro told USA TODAY.

Connor O'Dell, 29, said a 66-year-old relative reported her symptoms to Royal Caribbean during the cruise. He said neither a doctor nor nurse gave her an in-depth physical exam or asked her about preexisting conditions.

"We all knew the risks of going on the ship," O'Dell told USA TODAY. "The problem is that we were promised a set of protocols (or) adequate medical staffing and they were never adhered to."

– Morgan Hines

Sens. Elizabeth Warren and Cory Booker test positive for COVID-19

Senators Elizabeth Warren, D-Massachusetts, and Cory Booker, D-New Jersey, and Rep. Jason Crow, D-Colorado, have tested positive for COVID-19 in breakthrough cases with mild symptoms, they announced on Twitter.

"I regularly test for COVID & while I tested negative earlier this week, today I tested positive with a breakthrough case. Thankfully, I am only experiencing mild symptoms & am grateful for the protection provided against serious illness that comes from being vaccinated & boosted," Warren wrote. 

Booker tweeted: "I learned today that I tested positive for COVID-19 after first feeling symptoms on Saturday. My symptoms are relatively mild. I’m beyond grateful to have received two doses of vaccine and, more recently, a booster – I’m certain that without them I would be doing much worse."

The senators from Massachusetts and New Jersey have both been vocal proponents of the COVID-19 vaccine in Washington. Warren lost her older brother to the virus in May 2020. The Democrats are just two of several senators who have tested positive for COVID despite being fully vaccinated, including Lindsay Graham, R-SC and John Hickenlooper, D-Colo.

The latest congrespositive tests come amid a rise of COVID-19 cases across the nation and the omicron variant, which Dr. Anthony Fauci, the nation’s leading infectious diseases expert, said has an "extraordinary capability of spreading."

– Celina Tebor, USA TODAY

Contributing: The Associated Press; Karen Weintraub, USA TODAY