By Rong-Gong Lin Ii & Luke Money

Some health officials are calling it a hopeful sign that the first people known to be infected with the Omicron variant have had mild symptoms of COVID-19, although they warned it is still far too early to understand the implications of the newest coronavirus variant of concern.

A report issued over the weekend by the South African Medical Research Council said most of the patients in a Pretoria hospital who are believed to be infected with Omicron weren’t hospitalized because they had COVID-19 but for another medical reason.

Of the 42 patients, about 70% of them have no trouble breathing and do not need oxygen support.

“This is a picture that has not been seen in previous waves,” the report said; even at the start of previous waves, most hospitalized COVID patients have had trouble breathing. Still, “more time is required to fully answer the questions about the severity of COVID-19 caused by the new Omicron variant.”

California state epidemiologist Dr. Erica Pan seemed to be heartened by that preliminary assessment.

“It is very early, and patient population is young, but encouraging early data suggesting less [oxygen needed for patients] and less severity,” Pan tweeted.

Dr. Anthony Fauci, President Biden’s chief medical advisor for the pandemic, called the South Africa report “encouraging” in an interview, but added that “we have really got to be careful before we make any determinations that it is less severe, or it really doesn’t cause any severe illness comparable to Delta.”

Maria Van Kerkhove, an epidemiologist with the World Health Organization, agreed that it’s still too early to tell whether Omicron will result in more mild COVID-19 symptoms.

“Even if it is a mild disease, it’s important that we still act fast now to take measures to control its spread, because even if we have a large number of cases that are mild, some of those individuals will need hospitalizations … go into ICU, and some people will die,” she said. “More cases can mean more hospitalizations, more hospitalizations could mean more deaths and we don’t want to see that happen on top of an already difficult situation with Delta circulating globally.”

One of the biggest questions for the U.S. is what will happen as Omicron goes up against the Delta variant, which currently comprises 99.9% of analyzed coronavirus samples nationwide. It’s unclear whether Delta will remain the dominant strain in the U.S. or if Omicron will be able to displace it.

“What we don’t yet know is how transmissible it will be, how well our vaccines will work, whether it will lead to more severe disease,” said Dr. Rochelle Walensky, the director of the U.S. Centers for Disease Control and Prevention.

Concerns remain about how transmissible Omicron may be. Trevor Bedford of the Fred Hutchinson Cancer Research Center, an infectious disease researcher who has been studying coronavirus spread, said the Omicron transmission rate could render this variant “a much larger threat in terms of case counts than Delta.”

“The size of this wave will depend largely on the susceptible population. Although current data cannot fully address this, I suspect there is decent immune evasion, and some individuals protected from infection by Delta will be susceptible to Omicron,” Bedford tweeted.

In California, local health officials and scientists said the best way to prepare for Omicron is for unvaccinated people to get their shots and for vaccinated people to get their booster shots, if they are eligible to do so. Even if it turns out that the vaccines are less effective against Omicron, having a higher level of antibodies — particularly following a booster shot — could still provide decent protection against severe illness from COVID-19, Fauci has said.

Getting vaccinated and boosted is “the most effective tool we have to protect you from severe illness,” said Dr. Regina Chinsio-Kwong, a deputy health officer for Orange County.

Eight confirmed Omicron cases identified among California residents appear to have resulted in relatively mild symptoms.

All of the residents had been vaccinated, and the patients whose ages have been identified are all under age 50.

Five new Omicron cases were reported Friday night. They involved vaccinated residents of Alameda County who attended a wedding in Wisconsin on Nov. 27. All of them had mild symptoms of COVID-19.

Seven additional people, who also live in Alameda County, were linked to the cluster of cases, but officials haven’t yet identified the variant responsible for their infections.

One of the 12 wedding guests had recently returned from an international trip, according to a statement provided by the Alameda County Public Health Department.

Of the dozen infected residents, all are vaccinated and between the ages of 18 to 49. Most of them had received boosters, and none has required hospitalization.

Omicron has also been detected in recent travelers who live in Los Angeles County and San Francisco. All were vaccinated, and none have reported severe illness.

The first L.A. County resident’s symptoms are improving without medical care. That person’s infection was most likely travel-related, health officials said, as the resident had returned to L.A. after flying to South Africa via London on Nov. 22. A small number of close contacts have tested negative and have no symptoms.

On Monday, officials reported the county’s second confirmed Omicron case: a USC student who had recently returned from the East Coast. The student had mild COVID-19 symptoms and is self-isolating. Close contacts who have been identified are quarantining and being tested for infection.

The San Francisco resident, described only as someone between the ages of 18 and 49, had only mild symptoms, was not hospitalized and has already recovered. The resident recently traveled to South Africa, returned home Nov. 22 and became symptomatic on or around Thanksgiving. Close contacts of the resident thus far have tested negative.