It's still too early to predict whether Omicron's rapid spread will help push coronavirus from the pandemic phase to a more manageable endemic phase -- but "I would hope that that's the case," Dr. Anthony Fauci said Monday.
A disease that is endemic has a constant presence in a population but does not affect an alarmingly large number of people or disrupt society, as typically seen in a pandemic.
Since Omicron is highly transmissible but apparently less likely to cause as severe disease as some previous variants, it could mark a transition from this Covid-19 pandemic chapter to an endemic phase.
"But that would only be the case if we don't get another variant that eludes the immune response to the prior variant," Fauci told the Davos Agenda, a virtual event this week held by the World Economic Forum.
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"We were fortunate" that Omicron did not share some of the same characteristics as Delta, Fauci said. "But the sheer volume of people who are getting infected overrides that rather less level of pathogenicity."
"It is an open question as to whether or not Omicron is going to be the live virus vaccination that everyone is hoping for because you have such a great deal of variability with new variants emerging," he said.
That doesn't mean people should intentionally try to get the Omicron variant. Doctors say that's a terrible idea for several reasons.
And it doesn't mean the battle against Covid-19 is over -- especially as overwhelmed hospitals delay elective surgeries and schools switch to remote learning.
Health care systems -- some facing critical staffing shortages -- have treated more Covid-19 patients in recent days than ever. At least 156,676 Covid-19 patients in the US were hospitalized Monday, according to data from the Department of Health and Human Services.
And an average of 1,695 Americans died from Covid-19 every day over the past week, according to data from Johns Hopkins University.
Schools grapple with the Omicron surge
In Texas, all schools and offices in the Houston Independent School District were closed Tuesday due to rising infections in the area, the school district announced on its website. Classes are expected to resume Wednesday.
HISD encouraged students and staff to take "this extra day to mitigate potential exposure."
But New York City's mayor emphasized that classrooms in the nation's largest school district will remain open -- citing "good news" in the city's fight against Covid-19.
"We have not won yet," Mayor Eric Adams said Tuesday, but "we are winning."
Covid-19 hospitalizations have decreased from about 6,500 on January 11 to about 5,800 on January 16, city Health Commissioner Dr. Dr David Chokshi said.
But Chokshi warned Covid-19 numbers are still high, reinforcing the need for vaccination.
While districtwide remote learning is not an option, the mayor said, the city is in talks with the teachers' union about the possibility of a remote option for sick children who are isolating at home.
Meanwhile, a mask mandate in schools is under fire in Virginia.
Citing "individual liberty" and the availability of vaccines for K-12 students, newly inaugurated Gov. Glenn Youngkin issued an executive order stating parents will get to decide if their child must wear a mask in class, a departure from his predecessor's public health emergency order in August that masks were to be worn in schools.
Several districts in the Northern Virginia and metro Richmond area announced they will reject the latest order, which is set to begin January 24.
"Our layered prevention strategies have proven effective in keeping transmission rates low in our schools," Fairfax County Public Schools Superintendent Scott Brabrand said in a letter to the school community.
"Universal mask use has proven effective in keeping Covid-19 transmission rates low in our schools and ensuring schools remain safe and open," a statement from Arlington Public Schools said about its decision.
And an email from Henrico County Public Schools to parents and guardians reads, "Mask use is a vital component of the division's layered prevention measures," while noting the Centers for Disease Control and Prevention recommends masks in schools and that federal law requires masks on school buses.
Progress on future vaccines moves forward
To further get ahead of variants, new vaccines are under development.
Moderna should have data available on its Omicron-specific Covid-19 vaccine in March, company CEO Stephane Bancel said Monday.
"It should be in the clinic in the coming weeks. And we're hoping in the March timeframe, we should be able to have data to share with regulators to figure out the next step forward," he said in a panel conversation at Davos.
A combined Covid-19 and flu booster shot from Moderna could also be available in some countries by fall 2023, Bancel said, but he cautioned the goal date is a "best case scenario."
Doctors say Covid-19 vaccines and booster doses are the most effective way to ward off severe Covid-19 complications.
Booster doses have successfully demonstrated the ability to raise a person's antibody levels months after initial inoculations, helping to keep those at higher risk out of the hospital.
Early data out of Israel suggests a fourth dose of either the Pfizer/BioNTech or Moderna vaccines can elicit an increase in antibodies -- more than what has been seen following a third dose -- but it still might not be enough to protect against possible breakthrough infections caused by Omicron.
In December, Israel started trialing a fourth dose of the coronavirus vaccines for healthy participants ahead of a roll out of the additional booster shot to at-risk populations -- marking the first study of its kind among healthy people getting a fourth dose.
"I think that the decision to allow the fourth vaccine to vulnerable populations is probably correct," Dr. Gili-Regev Yochay, director of Infection Prevention Control Unit at the Sheba Medical Center, said Monday of the data. "It may give a little bit of benefit but probably not enough to support the decision to give it to all of the population, I would say."
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CNN's Jacqueline Howard, John Bonifield, Virginia Langmaid, Kristina Sgueglia, Dan Merica, Eva McKend, Ryan Nobles, Livvy Doherty, Carma Hassan and Alex Medeiros contributed to this report.