Surveillance of human- and swine-origin influenza in Hong Kong children
TF Leung1, PKS Chan2, KL Hon1, AM Li1
1 Department of Paediatrics, The Chinese University of Hong Kong
2 Department of Microbiology, The Chinese University of Hong Kong
1. Of 49 children aged 5 years recruited from three randomly selected kindergartens in the New Territories East Cluster, 49 provided at least one nasopharyngeal swab for influenza surveillance. Of them, 44 (89.8%) provided four bi-weekly nasopharyngeal samples between early February and late March 2012. Serial nasopharyngeal sampling is a feasible approach for respiratory virus surveillance in local preschool children.
2. Of all samples, 13 from 12 (24.5%) children were influenza-positive, including those from 10 (20.4%) of 49 children under surveillance and three of 10 children who provided illness visit samples. Asymptomatic and mildly symptomatic influenza infection is common in these young children.
3. Of the 49 children, 27 (55.1%) had received influenza vaccination within 3 years, but only two (16.7%) who were infected with influenza had been vaccinated within the past 12 months. The low level of vaccine uptake is probably the main cause of influenza infection in our preschoolers.
4. Influenza infection was not associated with any personal or environmental factors, including influenza vaccination.