Identification of the child with influenza A (H1N1): Clinical criteria versus the rapid influenza A-B test

Introduction: During the influenza A (H1N1) pandemic infection, the Ministry of Health in Mexico recommended that it be considered as a suggestive clinical picture in patients with fever, cough and headache. In some places where the resource was available, the rapid seasonal influenza (A-B) test was used as an alternative identification strategy. Methods: From April 2009 to May 2010, patients under 18 years of age with acute respiratory tract symptoms were included in a retrospective study. They underwent the following procedures: 1) application of the clinical criteria recommended by the federal Ministry of Health during the A (H1N1) pandemic; 2) rapid test for seasonal influenza (A-B), and 3) search for the influenza A (H1N1) virus by means of the real time polymerase chain reaction (RT-PCR). The study was approved by the research and ethics committee at the Central South Hospital of the government-owned Mexican Petroleum Company (PEMEX). Results: One hundred and thirty pediatric patients with a median age of eight years and a range between one and 17 years were included. Taking into account the Ministry of Health’s criteria, we found the following: 50% sensitivity, 69% specificity, 80% positive predictive value and 27% negative predictive value versus the rapid test that displayed 82% sensitivity, 70% specificity, 80% positive predictive value and 27% negative predictive value. Conclusions: Clinical criteria display low sensitivity in the infected children studied, whereas the rapid influenza A-B test constitutes a better option to identify these patients.