New York, Nov 19 : New York City has reached the threshold of 3 per cent Covid-19 test positivity rate on a seven-day average, which "means public school buildings will be closed", Mayor Bill de Blasio said. The closures will come into effect from Thursday onwards, Xinhua news agency reported. "Health and safety have always been our first priority for @NYCSchools students, staff, and families," de Blasio said in a series of tweets on Wednesday. "We must fight back the second wave of Covid-19. To protect our school communities and our city, beginning tomorrow, all @NYCSchools buildings will be closed, and all learning will proceed remotely, until further notice," he added. Meanwhile, the Twitter account of NYC Public Schools said that "starting tomorrow, all @NYCschools buildings are closed for in-person learning until further notice". "All students who were learning in school buildings part of the week will transition to remote learning every day," the tweet added. New York City's public school system, accommodating more than 1.1 million students, is the largest of its kind in the US. Currently, New York City's overall coronavirus death toll and caseload have increased to 24,146 and 285,275, respectively. /IANS