By Maria Caspani

NEW YORK (Reuters) – Public high schools in New York City will welcome students back for in-person instruction on March 22, Mayor Bill de Blasio announced on Monday, the latest step by the United States’ largest school system to open classrooms shuttered due to COVID-19.

“We have all the pieces we need to bring high school back and bring it back strong, and, of course, bring it back safely,” de Blasio told a news conference. “We are bringing our schools back fully in September, period.”

The mayor has made restarting in-person instruction a priority, even as health experts have warned that teenagers are more likely to spread the virus than younger children, making the reopening of public high schools riskier than lower grades.

Students in Los Angeles, Chicago and other big cities have been shut out of the classroom since last year, as officials struggle to come to agreements with teacher unions on restarting in-person classes prior to widespread vaccinations.

Sari Rosenberg, who teaches at high school in Manhattan, said she misses the classroom but believes the risk remains too high given that teenagers can spread the disease without symptoms and teachers and staff are still getting inoculated.

“I think that it’s premature,” Rosenberg said.

Reopening the city’s public high schools will serve as the first major test for incoming schools chancellor Meisha Porter, who will take over from Richard Carranza this month. Carranza resigned from the post last month.

Porter said on Monday that about 55,000 high schoolers — out of a total population of 282,000 high school students — will resume in-person education on March 22.

New York City shut down schools in mid-November due to an increasing COVID-19 infection rate and has gradually brought students back to classrooms, starting with the youngest students and followed by middle school students last month.

De Blasio had promised high school students would not be far behind.

New York City’s school system is the largest in the United States with 1.1 million students and 1,800 buildings.

(Reporting by Maria Caspani and Nathan Layne; Editing by Chizu Nomiyama and Jonathan Oatis)