New York City has been ordered to close its schools from Thursday, amid a Covid-19 spike.
The decision to close the US’s largest public school system comes as positive test rates for the virus surpassed the 3% threshold, officials say.
It will affect some 300,000 children.
New York, where 35,000 residents have died with coronavirus, was the epicentre of the outbreak in the US in the spring. It now appears to be facing a new wave.
A letter from New York City Schools Chancellor Richard Carranza released on Wednesday informed parents that all schools would close and classrooms would immediately shift to online learning “until further notice”.
“You will hear from your principal shortly about next steps for you and your student. Please note that this is a temporary closure, and school buildings will reopen as soon as it is safe to do so.”
The move comes only eight weeks after the school system reopened to students.
Bill de Blasio, the New York mayor, said: “No one is happy about this decision. We all in fact are feeling very sad about this decision because so much good work has been put into keeping the schools open, opening them up to begin with.”
However, he said that officials had “set a very clear standard” on safety metrics that needed to be met in order for schools to take pupils, “and we need to stick to that standard”.
“I want to emphasise to parents, to educators, to staff, to kids that we will intend to come back and come back as quickly as possible,” he said.
The school closure is the latest measure amid attempts to curb a fresh outbreak of cases.
Mr de Blasio had previously committed to shutting schools if the infection rate reached 3% of the population for a week average – which happened on Wednesday.
Last week further restrictions were put into place – including bars and restaurants moving to takeaway-only after 22:00 and parties at private residences being limited to 10 people.
The decision to close the schools is in contrast to measures in Europe, where businesses have closed but schools largely remain open.
The move, which represents a major backslide for the city’s’ coronavirus recovery, has also left parents scrambling for last-minute childcare options.