The Omicron variant of the coronavirus has spread to about one-third of US states, but the Delta version remains the majority of COVID-19 cases nationwide, US health officials said on Sunday.
Though the emergence of the new variant has caused alarm worldwide, Dr. Anthony Fauci, the top US infectious disease official, told CNN "thus far it does not look like there's a great degree of severity to it" but he added that it was too early to draw definitive conclusions and more study is needed.
Fauci also hoped the United States would lift its ban on travelers from southern African countries in a "reasonable period of time." The South African government has complained it is being punished - instead of applauded - for discovering the new variant and quickly informing international health officials.
Fauci praised South Africa for its transparency and said the US travel ban was imposed at a time "when we were really in the dark" and needed time to study the variant.
"We all feel very badly about the hardship that that might have put upon not only South Africa but the other African countries," he added on CNN's "State of the Union."
At least 15 US states have reported Omicron cases: California, Colorado, Connecticut, Hawaii, Maryland, Massachusetts, Minnesota, Missouri, Nebraska, New Jersey, New York, Pennsylvania, Utah, Washington and Wisconsin, according to a Reuters tally.
Many of the cases were among fully vaccinated individuals with mild symptoms, although the booster shot status of some patients was not known.
Despite several dozen Omicron cases, the Delta variant still accounts for 99.9% of the 90,000 to 100,000 new cases of COVID each day in the United States https://tmsnrt.rs/2WTOZDR, CDC Director Dr. Rochelle Walensky told ABC News in an interview.
"We are everyday hearing about more and more probable cases so that number is likely to rise," she said.
Louisiana's Department of Health said on Saturday that a Norwegian Cruise Line Holdings Ltd cruise ship set to dock in New Orleans with more than 3,000 passengers has detected 10 cases of COVID-19 on board.
The Norwegian Breakaway left New Orleans on Nov. 28 and had stops in Belize, Honduras and Mexico, officials said, adding everyone on board would be tested and provided with post-exposure and quarantine public health guidance by the CDC.
COVID-19 vaccine makers are looking to quickly tweak their shots to target Omicron and US regulators have vowed speedy reviews, but that could still take months.
"Certainly, FDA (Food and Drug Administration) will move swiftly and CDC will move swiftly," Walensky said.
Moderna Inc has said it could seek US approval for an updated vaccine as soon as March, but company officials in television interviews on Sunday said it still take time to increase output.
Moderna Co-founder and Chairman Noubar Afeyan told CNN it would take another seven to 10 days to gather key Omicron data. Then, it "will take a good 60 to 100 days" to deploy an Omicron-specific shot, although other options like a higher dose of the current booster are being explored, he said.
US government officials are also working with vaccine makers Pfizer Inc and Johnson & Johnson on updated shots.
Pfizer and Merck & Co Inc are also pursuing COVID-19 pill treatments.