Mayor Bill de Blasio announced Tuesday that the city’s public schools would be doubling their testing efforts when students return to class on Jan. 3.

After the holiday break, testing will include both unvaccinated and vaccinated students. It had previously been limited to just unvaccinated students.

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Also, if a classroom has a positive COVID-19 case, each classmate will be given an at-home test. If they are asymptomatic and test negative, they will be able to return to class the next day.

“This is really a sea change in thinking in terms of public safety,” said the mayor, who stressed the importance of keeping schools open amid the rise in COVID-19 cases.

Fueled by the super-contagious Omicron variant, new coronavirus cases in the city have rocketed from an average of about 3,400 a day in the week that ended Dec. 12 to 22,000 in the week that ended Sunday. Hospitalizations also have risen, but not as sharply.

Mayor de Blasio was joined by Mayor-elect Eric Adams and Gov. Kathy Hochul during Tuesday’s media availability.