Twelve Orthodox Jewish day schools in Bergen County, N.J., are closed until at least Friday, March 20, in an effort to stem the number of cases of the coronavirus there.

At least 15 people in Bergen County have tested “presumptive” positive for the coronavirus, or COVID-19. (A presumptive positive means the results have not be verified by the Centers for Disease Control and Prevention.) Nationwide, more than 1,270 people have the virus—a number that experts say is probably not indicative of the true number of people ill because of a limited number of test kits available.

In a joint letter to parents, signed by the leaders of all the schools, the administrators wrote, “In consultation with medical specialists and representatives from the Bergen County school district, local Jewish day-school leaders have been working together to create a community-wide approach to dealing with this rapidly changing and evolving situation, one that will hopefully slow the spread of the coronavirus in our community. At this time, the schools’ closures will begin on Thursday, March 12th and will remain in effect through Friday, March 20th. Our school leaders will remain in regular contact with each other, the Department of Health and other medical authorities, to discuss the impacts of the coronavirus on our community and how best to continue addressing them proactively.”

Because of the nature of the Bergen County Jewish community, families are often affiliated with more than one school, with significant interaction among the teachers and student populations. Several of the schools reported having a parent, staff member or student with symptoms of the virus.