Table 1 Timeline of school closures

April 23, 2009 - The first suspected 2009 H1N1 cases in a school in the United States are identified at St. Francis Preparatory School in New York City. Eight confirmed cases were reported on April 26 [7].

April 24, 2009 - All schools in Mexico City--serving about seven million students--are closed as a social distancing measure to slow the spread of 2009 H1N1 [8].

April 25, 2009 - Byron Steele High School in Cibolo, Texas, is the first school in the United States closed because of 2009 H1N1. The following day, all schools in Schertz-Cibolo-Universal City Independent School District are closed by the Texas Department of State Health Services [9].

April 26, 2009 - School officials close St. Francis Preparatory School to disinfect the school. The same day, CDC recommends closing schools for seven days when a case is identified [10].

May 1, 2009 - The U.S. Centers for Disease Control and Prevention recommends that schools close for up to 14 days if a case of 2009 H1N1 is identified [11].

May 5, 2009 - CDC changes its guidance to recommend that schools generally do not need to close and should, instead, keep ill children home for at least seven days [12].

June 2, 2009 - New York City closes its final school in response to 2009 H1N1. New York continued school closures well after CDC ceased recommending closure, with the justification that closure would protect particularly vulnerable students from within-school transmission [13].

August 7, 2009 - CDC recommends against school closures in most cases, instead recommending that ill children remain at home, as part of its comprehensive guidance for schools to use during the Fall semester [14].