Dec 28 (Reuters) - New York City will stop quarantining entire classrooms exposed to the coronavirus and will instead prioritize a ramped-up testing program so that asymptomatic students testing negative for COVID-19 can remain in school, officials said on Tuesday. A day earlier, the U.S. Centers for Disease Control and Prevention (CDC) shortened the recommended isolation time for Americans with asymptomatic cases of COVID-19 to five days from the previous guidance of 10 days. read more President Joe Biden has pledged to ease a shortage of COVID-19 tests with the Omicron variant threatening to overwhelm hospitals and stifle travel plans as it spreads across the country this holiday week. read more The Omicron variant was estimated to be 58.6% of the coronavirus variants circulating in the United States as of Dec. 25, CDC data showed on Tuesday. Mayor Bill de Blasio described New York"s new policy as "Stay Safe, and Stay Open" and said it will take effect on Jan. 3. About a million New York City public school students are scheduled to return from holiday break on Monday. New York City Mayor-elect Eric Adams, de Blasio and New York Governor Kathy Hochul made the announcements at a news conference. New York City aims to detect more infections while mitigating disruptions as officials described remote learning as "a failed experiment." The city"s previous policy was to quarantine unvaccinated close contacts of infected students for 10 days. REUTERS/Ronen Zvulun People wait in line to take coronavirus disease (COVID-19) tests at pop-up testing site in New York City, U.S., December 14, 2021. REUTERS/Brendan McDermid REUTERS/Ronen Zvulun 1/2 People wait in line to take coronavirus disease (COVID-19) tests at pop-up testing site in New York City, U.S., December 14, 2021. REUTERS/Brendan McDermid Instead of sending classes of unvaccinated students home to learn online when a student tests positive, the students will be given rapid at-home tests. If they are asymptomatic and test negative, they can return the day after their first negative test. Students will be given a second at-home test within seven days of their exposure, according to the announcement. The step raised some concerns among parents. One tweeted that schools should be kept remote for at least a week"s cushion following potential holiday gathering and travel exposure. Others called for mandatory testing for all children, as well as school employees. Broadway"s revival of "The Music Man," the hottest ticket in town, on Tuesday canceled performances for five days after star Hugh Jackman tested positive for COVID, becoming the latest New York City show to fall victim to the surging coronavirus. read more New York will also sharply limit the number of people it allows in Times Square for its New Year"s Eve celebration. read more Separately, Biden on Tuesday revoked a proclamation put in place last month that imposed travel restrictions on eight southern African nations, including South Africa, after the emergence of the Omicron variant.