(CNN) As the first case of the Omicron variant in the US was detected on Wednesday, health officials are urging Americans not to wait any longer to receive a vaccination or booster to better protect themselves and others.
With the Delta variant still spreading -- and travel expected to increase this month -- vaccinations are key to safely enjoying end-of-the-year festivities.
"Just as I said and I'll say it again, if you have a vaccinated situation, enjoy the holidays with your family in a family setting," National Institute of Allergy and Infectious Diseases director Dr. Anthony Fauci said at a CNN Global Town Hall on Wednesday.
Results from studies being performed on Omicron to determine its severity and transmissibility are expected in the coming weeks.
But it's clear that vaccinations have been effective against other coronavirus variants, including the Delta variant that is still raging in hotspots across the US. And Fauci said their success against Delta may also be seen with Omicron.
"That's where we're hoping we'll see with the Omicron variant, that if you get your levels high enough it'll spill over and get cross-protection against that variant," Fauci said, adding that it is still not clear whether people will need yearly or more frequent Covid-19 booster shots.
Some Americans may be asking if they should wait to get a Covid-19 booster depending on what scientists learn about the Omicron variant, but Fauci said to not wait.
"Get that extra boost now," Fauci said. "The level of antibodies that rise and go up following a boost is much, much higher than the peak level that you get after your second dose of a two-dose vaccine."
The first confirmed case in the US of the Omicron variant was identified in California on Wednesday. Fauci said the person was fully vaccinated and is experiencing "mild symptoms, which are improving at this point."
A second case has been found in a Minnesota resident who had traveled to New York City. The person -- an adult male -- was vaccinated, had mild symptoms on November 22 and was tested on November 24. He has since recovered, according to the Minnesota Department of Health.
New York officials are asking individuals who attended a conference at the Javits Center between November 18-22 to get tested following revelations that the Minnesota resident also attended the conference. Proof of vaccination was required to attend the convention, New York Gov. Kathy Hochul said Thursday.
Health officials expect to find more Omicron cases as genetic sequencing continues around the country.
The Delta variant is still at the forefront of health officials' minds as it accounts for practically all new infections. Nearly 58,000 Americans are hospitalized with Covid-19, according to data from US Health and Human Services.
Dr. Richard Besser, former acting director of the US Centers for Disease Control and Prevention, told CNN's Anderson Cooper on Wednesday that he hopes so-called "Covid-19 fatigue" will not prevent people from getting vaccinated.
"Even if the Omicron strain doesn't turn out to be any worse, we are losing close to a thousand people every day from the Delta variant, and that in and of itself is a reason for people to get boosted," Besser said.
With Omicron detected in at least 25 countries and territories, officials are working to find those infected and are cautioning those at higher risk of severe symptoms to avoid travel.
In the US, the Biden administration announced restrictions last week against travelers, with the exception of US citizens and legal permanent residents, from entering the US from eight southern African nations. The Omicron variant was first identified by South African scientists.
Following an earlier CDC order that airlines must collect contact information from passengers before their arrival to notify of possible Covid-19 exposures, the agency plans to provide the names of those on flights from southern Africa to state and local public health departments, a health official confirms. Delta Air Lines, United Airlines and American Airlines told CNN they are complying with the directive.
Fauci told a White House news briefing Wednesday that the travel bans are meant to be "temporary" and were needed to slow the variant's arrival, rather than the highly unlikely task of stopping it completely.
"No one feels -- I certainly don't -- that a travel ban is going to prevent people who are infected from coming to the United States," Fauci said. "But we needed to buy some time to be able to prepare, understand what's going on."
The World Health Organization on Tuesday said those who are not fully vaccinated or do not have proof of prior infection, as well as those over 60 years of age or have comorbidities such as heart disease, cancer or diabetes should "postpone travel to areas with community transmission" due to the Omicron variant.
With more than 785,000 Americans dead from Covid-19 and hospitals still stretched to capacity in some parts of the country, two recent studies further demonstrate how damaging the virus has been as well for those who survived.
People who lived through a severe case of Covid-19 -- those requiring hospitalization -- were about 2.5 times more likely to die within a year of diagnosis than those who did not have Covid-19, according to a study published Wednesday in the journal Frontiers in Medicine, and were nearly two times more likely to die than those who had a mild or moderate case.
The study from researchers at the University of Florida found no significant difference in mortality risk between patients with mild or moderate Covid-19 and those who did not have Covid-19, suggesting that preventing severe Covid-19 infections is the most effective ways to avoid deaths.
Only about 20% of "downstream deaths" among Covid-19 patients were from respiratory or cardiovascular causes, the study determined.
"Since these deaths were not for a direct Covid-19 cause of death among these patients who have recovered from the initial episode of Covid-19, this data suggests that the biological insult from Covid-19 and physiological stress from Covid-19 is significant," the researchers wrote. The de-identified medical records of nearly 14,000 patients in 2020 were used in their study.
Another analysis, from the United Network for Organ Sharing, found that one in every 10 lung transplants in the US in 2021 has gone to a patient with lung damage related to Covid-19.
In the last five months of 2020, only about 2% -- one in every 50 -- lung transplants went to Covid-19 patients, data showed.