Rapid Influenza Test Evaluated for Children

A rapid influenza assay has been evaluated for use with elementary school children and compared with a molecular test.

The test is a lateral-flow immunoassay that uses monoclonal antibodies specific for influenza viral nucleoprotein antigens and detects and differentiates between influenza A and B.

Public Health specialists at the University of Pittsburgh, (Pittsburgh, PA, USA), collected 278 pairs of nasal swabs from children during home visits during the 2007-2008 influenza season. One swab was tested with the immunoassay, which takes 10 minutes or less, and the other with a real time, reverse transcriptase polymerase chain reaction (RT-PCR). A total of 104 samples were positive by RT-PCR test, and of these, 54/104 (52%) were influenza A and 50/104 (48%) were influenza B.

Only 28/104 (27%), of these influenza-positive samples were detected as positive by QuickVue rapid immunoassay influenza testing. Influenza A accounted for 17 (61%) of the 28 positive tests, and of the remaining 11 (39%) were influenza B. The sensitivity and specificity of rapid influenza testing, using the QuickVue Influenza A+B test (Quidel; San Diego, CA, USA), in the students with influenza like illness who were tested was 27% (28/104) and 97% (168/174), respectively. The overall positive predictive value was 82% (28/34) and 69% (168/244) for negative predictive values. There was no statistically valid correlation between the semiquantitative PCR result and the QuickVue result.

The authors concluded that community testing includes patients who represent the entire spectrum of illness, with the majority exhibiting mild to moderate symptoms and not requiring medical attention. Viral load, technique, and the use of nasal swabs were examined as contributing factors to the low sensitivity of the QuickVue test, but were not found to be explanations for this result. If tests with higher sensitivities in community settings were available, they could be used as a part of an improved surveillance and early warning system for influenza activity and rapid confirmation of outbreaks. The study was published in March 2011, in the journal Influenza and Other Respiratory Viruses.

Related Links:
University of Pittsburgh
Quidel