Direct Fluorescent-Antibody Testing Followed by Culture for Diagnosis of 2009 H1N1 Influenza A

During the 2009 H1N1 influenza A outbreak, 773 children were tested for influenza by direct fluorescent-antibody testing with PCR confirmation. Direct fluorescent-antibody testing has a specificity of 99.6% but a sensitivity of only 65.0%. Physicians should recognize diagnostic limitations of direct fluorescent-antibody testing, which missed one-third of infected individuals.