Public schools in New York will remain closed until the end of the academic year due to the COVID-19 pandemic, New York City Mayor Bill de Blasio said at a press briefing on Saturday.

De Blasio said reopening of learning institutions is unrealistic due to the amount of preparation required to do it safely.

New York is the most COVID-19- affected state in the United States, having recorded over 5,800 deaths.

Governor Andrew M. Cuomo signed an executive order last month directing all schools in New York to close by March 18 for an initial period of two weeks ending April 1. An escalation of the situation made the reopening of the schools impossible, as the state deteriorated to become the epicenter of the U.S. outbreak.

In his briefing on Saturday, De Blassio said bringing students back until June would not result in meaningful academic work, noting that buildings would have to shut down in case of any individual COVID-19 cases.

The New York City school system is the largest in the U.S., with some 1.1 million students.

(With input from CNN)