By Doina Chiacu and David Brunnstrom
WASHINGTON (Reuters) - U.S. health officials urged Americans on Sunday to get booster shots, wear masks and be careful if they travel over the winter holidays, as the Omicron variant raged across the world and was set to take over as the dominant strain in the United States.
The government is gearing up for the next phase of battle in a two-year fight against a virus that has killed 800,000 people in the United States and disrupted every aspect of daily life.
Two U.S. senators, Democrats Elizabeth Warren and Cory Booker, said on Sunday they tested positive for COVID-19 but were experiencing only mild symptoms.
Warren, 72, said on Twitter she was "grateful for the protection provided against serious illness that comes from being vaccinated and boosted," and urged other Americans to do the same.
Dr. Francis Collins, director of the National Institutes of Health, told CBS' "Face the Nation" that the number of Omicron cases will rise steeply in the next two weeks.
"A big message for today is if you've had vaccines and a booster, you're very well protected against Omicron causing you severe disease. So, anybody listening to this who's in that 60% of Americans who are eligible for a booster but haven't yet gotten one: This is the week to do it. Do not wait," he said.
Omicron is multiplying rapidly, making COVID-19 vaccinations and booster shots more crucial than ever, chief White House medical adviser Dr. Anthony Fauci said on Sunday. Currently, 27% of U.S. residents have not gotten even a single dose of vaccine, according to the Centers for Disease Control and Prevention.
"It is just, you know, raging through the world," Fauci, director of the National Institute of Allergy and Infectious Diseases, said on NBC's "Meet the Press."
Omicron has been found in 43 out of 50 U.S. states and around 90 countries so far.
New York state recorded 22,478 positive COVID-19 cases on Saturday, Governor Kathy Hochul tweeted on Sunday, marking the state's third daily record in new positive cases in three days.
More than half of the state's new cases recorded on Saturday were in New York City, where Mayor Bill de Blasio called for the country to "go on a war footing" to fight the Omicron variant with more vaccinations. He said the city would spend $10 million on an advertising campaign to promote booster shots.
The number of cases is doubling in 1.5 to three days in areas with community transmission, the World Health Organization said on Saturday.
In certain regions of the United States, 50% of the COVID-19 tests genetically sequenced detected the Omicron variant, Fauci told CNN, "which means it's going to take over."
The virus is forcing sports leagues to reschedule games and entertainment venues to cancel shows. The National Basketball Association postponed five additional games on Sunday.
The National Hockey League said it agreed with its players association to continue its 2021-22 regular-season schedule, as nearly all players and staff are vaccinated, but would temporarily shut down individual teams on a case-by-case basis. It also postponed cross-border games involving Canadian and U.S.-based teams through Thursday.
In a reminder of the pandemic's early spread on cruise ships, about four dozen guests and crew members aboard Royal Caribbean's Symphony of the Seas ship, which docked in Miami on Saturday, tested positive for COVID-19, NBC News reported, citing a statement from the company.
Colorado Governor Jared Polis told NBC he was considering changing the definition of fully vaccinated in his state to three shots from two. "I wish they'd stop talking about it as a booster. It really is a three-dose vaccine," he said.
BOOSTERS, TESTING, SURGE TEAMS
President Joe Biden plans to give a speech on Tuesday about the rising COVID-19 cases, hammering home his message to unvaccinated Americans to get a shot and for those who are vaccinated to get a booster.
Part of Biden's strategy is to focus on increased testing, Fauci told CNN's "State of the Union."
"We really need to flood the system with testing. We need to have tests available for anyone who wants them," he said.
Hospitals in some parts of the country are already becoming strained by COVID-19 patients and things are likely to get worse, the health officials said.
"The government is prepared now to start sending out surge teams as needed to places that are really hit hard and the president's going to have more to say about that in a speech on Tuesday," Collins said.
Neither Fauci nor Collins urged vaccinated Americans to cancel travel plans - just to wear a mask at all times in airports, on planes, trains and buses.
"I'm not going to say you shouldn't travel, but you should do so very carefully," Collins said.
(Reporting by Doina Chiacu and David Brunnstrom; Additional reporting by Nathan Layne in Wilton, Connecticut; Editing by Lisa Shumaker, Daniel Wallis and Peter Cooney)