Figure 2. Cumulative virology test volumes and influenza A–positive results, North Shore–Long Island Jewish Health System, New York City metropolitan area, USA, April 24–May 15, 2009. INFA RAP, rapid antigen test for influenza A; DFA, direct immunofluorescent antibody test; VCR, rapid respiratory virus culture by R-Mix (Diagnostic Hybrids Inc., Athens, OH, USA); RVP, Luminex xTAG Respiratory Virus Panel (Luminex Molecular Diagnostics, Toronto, Canada). White bars, number of tests with negative results for influenza A.; black bars, number of test results positive for influenza A. Actual numbers are included above the bars. For influenza A, the percentages of samples positive for influenza A are shown in parentheses.