December 29 coronavirus pandemic and Omicron variant news

Dr. Rochelle Walensky, director of the US Centers for Disease Control and Prevention, said on CNN’s New Day Wednesday the decision to shorten the isolation period for those with asymptomatic Covid-19 infection was driven by evidence around transmission and what isolation protocol people “would be able to tolerate.”

CDC “really wanted to make sure” that the first five days were spent in isolation, Walensky said, adding that they were asking people to mask in the last five days. 

They also looked at epidemiology, she said, and they are seeing and expecting even more cases of Omicron, many of which were mildly or asymptomatic. 

Finally, they looked at behavioral science, “what will people actually do when people need to get back to work? What is it that they will actually do? And if we can get them to isolate, we do want to make sure that they’re isolating in those first five days when they’re maximally infectious.” 

Asked if the decision had as much to do with business as with science, Walensky said “it really had a lot to do with what we thought people would be able to tolerate.” 

There have been relatively low rates of isolation throughout the pandemic, she said, adding “some science has demonstrated less than a third of people are isolating when they need to.” 

“We really want to make sure that we had guidance in this moment where we were going to have a lot of disease that could be adhered to, that people were willing to adhere to. And that spoke specifically to when people were maximally infectious. So it really spoke to both behaviors as well as what people were able to do,” she said.

Walensky also said that the old 10 day guidance was “conservative,” when asked why they didn’t make the change sooner. 

“But, in the context of the fact that we were going to have so many more cases, many of those would be asymptomatic or mildly symptomatic, people would feel well enough to be at work, they would not necessarily tolerate being home and that they may not comply with being home,” she said. “This was the moment that we needed to make that decision and those changes.”

Dr. Rochelle Walensky, director of the US Centers for Disease Control and Prevention, advised people who may have coronavirus symptoms to get a PCR test if they get a negative antigen test.

"Antigen tests still work quite well, and they work well especially in places that we're using them, like in higher education, in test to stay in schools where we’re doing several tests, one every other day, every third day, and that’s really when they work well as well. So, we still are encouraging their use, they may not work as well as they had for the Delta variant,” Walensky continued.

On Monday, the CDC shortened the recommended times that people should isolate when they've tested positive for Covid-19 from 10 days to five days if they don't have symptoms – and if they wear a mask around others for at least five more days.

The CDC also shortened the recommended time for people to quarantine if they are exposed to the virus to a similar five days if they are vaccinated. People who are fully vaccinated and boosted may not need to quarantine at all, the CDC said.

Walensky reiterated the agency's stance that kids "can safely return to school" as long as they are testing for Covid-19 regularly.

Greece is bringing forward restrictions that were due to take effect on Jan. 3 in an effort to curb the spread of the Omicron variant which has become dominant across the country.

Greece registered 21,657 new coronavirus cases on Tuesday – its highest daily record since the start of the pandemic.

Health Minister Thanos Plevris announced in a news conference that the new restrictions will instead take effect tomorrow at 6 a.m. local.

The measures include the closure of hospitality and entertainment venues at midnight, a ban on standing customers and a maximum limit of six people per table, reduced sports venue capacity and the reintroduction of 50% remote working for public and private sectors.

Plevris added that music will also be banned in entertainment venues. 

Omicron variant cases are doubling every two to three days, French Health Minister Olivier Veran told a parliamentary health commission in Paris Wednesday.

Veran also told French lawmakers that his European colleagues are also seeing a similar trend.

To curb the spread of Omicron, the French government will require a vaccine pass that will to come into force from Jan. 15 in restaurants as well as in some of the country’s public transportation and proof of vaccination will be required.

Hospitals and elderly care homes will just be governed by the current health pass.

Earlier, the French health minister said France has seen 208,000 cases in the last 24 hours. Every second more than two French people test positive, he noted.

“Delta has not had its final word,” he said.

The official said about the unvaccinated, there was “very little chance this time you’ll be able to slip through the net,” when it comes to getting infected.

He said at least one million people were infected at this point.

CNN readers from around the world have asked more than 150,000 questions (and counting) about coronavirus. One of those questions was if people who have previously had Covid-19 can still get infected with the Omicron variant. The answer is yes.

In fact, the first confirmed Omicron-related death in the US was a man who previously had Covid-19.

The Texas man, in his 50s, had not been vaccinated, Harris County health officials said.

For months, the US Centers for Disease Control and Prevention has said vaccines give stronger protection against Covid-19 than previous infection alone.

With the new Omicron variant, the risk of getting reinfected is 5.4 times higher with Omicron than it was with Delta, according to a team of disease modelers at Imperial College London.

“This suggests relatively low remaining levels of immunity from prior infection,” the team wrote in a December report.

Health experts say the best way to help protect against the Omicron variant is to get vaccinated and boosted.

Dr. Rochelle Walensky, director of the US Centers for Disease Control and Prevention, told CNN’s New Day Wednesday that the rapid speed of Omicron spread meant that early predictive estimates about how prevalent it is can be less stable.

The CDC said Tuesday that the Omicron variant caused 58.6% of new coronavirus cases in the US last week, which is lower than previously thought, but the agency has said it will adjust its estimates based on additional sequencing.

“But, I think the important thing to note here is that there are areas of this country that have 20% Omicron, there are areas of this country that have 90% of cases Omicron, and what we have seen and what our predictions have demonstrated is that this is a rapidly increasing variant in the United States,” she said.

The US Centers for Disease Control and Prevention updated their isolation and quarantine guidelines on Monday for those who test positive with Covid-19.

Here's what to know:

The update did not explicitly say how long infected people who still had symptoms need to isolate. The CDC has previously said people with symptomatic Covid-19 should isolate for 10 days.

“To calculate your 10 full day isolation period, day 0 is your first day of symptoms,” the CDC said Dec. 9. “Day 1 is the first full day after your symptoms developed.”

The decision to reduce isolation times for those who are asymptomatic after five days was motivated by research showing the majority of Covid-19 spread “occurs early in the course of illness, generally in the 1-2 days prior to onset of symptoms and the 2-3 days after,” the CDC said on Dec. 27.

“Therefore, people who test positive should isolate for 5 days and, if asymptomatic at that time, they may leave isolation if they can continue to mask for 5 days to minimize the risk of infecting others.”

Have more coronavirus questions? We're answering them here.

The US hit a seven-day average of 265,427 new Covid-19 cases on Tuesday, blowing past the country's previous record of about 252,000 daily cases, reported nearly a year ago on Jan. 11.

The new peak, according to data from Johns Hopkins University, comes as rapid acceleration of infections continues in the United States.

Here's a look at how Covid-19 is spreading in communities across the country:

Track Covid-19 cases in the US here.

CNN's Holly Yan and Amir Vera contributed reporting to this post. 

US Centers for Disease Control and Prevention Director Dr. Rochelle Walensky explained the agency's stance on rapid tests on CNN’s New Day Wednesday. Walensky said the CDC does not recommend rapid tests for ending Covid-19 isolation because they don’t know how they perform or predict how transmissible people are at the end of infection. 

The US Food and Drug Administration has not authorized them for that use, she said, and it is not known how they perform. 

“So what we said was, well, if you got a rapid test at five days and it was negative, we weren’t convinced that you weren’t still transmissible,” she said. “We didn’t want to leave a false sense of security, we still wanted you to wear the mask. And if it was positive, we still know the maximum amount of transmission was behind you, we still wanted you to wear a mask and given that we were not going to change our recommendations based on the result of that rapid test, we opted not to include it.” 

Asked why health care workers need a negative test just a few days ago, according to CDC guidance, but the general public doesn’t, Walensky said that infection control recommendations in health care workplaces are “always more stringent” than for the general population. 

She also said that the decision had nothing to do with shortages of rapid tests, saying “this decision really from an isolation standpoint had everything to do with the fact that we wouldn’t change our guidance based on the result of that rapid test. And you know that it didn’t have anything to do with any shortage at all, because we recommend rapid tests for those in quarantine.” 

You can read more about the CDC's updated isolation guidelines here.