Characteristics of US public schools with reported cases of novel influenza A (H1N1).

OBJECTIVE The 2009 pandemic of influenza A (H1N1) has disproportionately affected children and young adults, resulting in attention by public health officials and the news media on schools as important settings for disease transmission and spread. We aimed to characterize US schools affected by novel influenza A (H1N1) relative to other schools in the same communities. METHODS A database of US school-related cases was obtained by electronic news media monitoring for early reports of novel H1N1 influenza between April 23 and June 8, 2009. We performed a matched case-control study of 32 public primary and secondary schools that had one or more confirmed cases of H1N1 influenza and 6815 control schools located in the same 23 counties as case schools. RESULTS Compared with controls from the same county, schools with reports of confirmed cases of H1N1 influenza were less likely to have a high proportion of economically disadvantaged students (adjusted odds ratio (aOR) 0.385; 95% confidence interval (CI) 0.166-0.894) and less likely to have older students (aOR 0.792; 95% CI 0.670-0.938). CONCLUSIONS We conclude that public schools with younger, more affluent students may be considered sentinels of the epidemic and may have played a role in its initial spread.