Influenza surveillance in Hong Kong: results of a trial Physician Sentinel Programme.

The H5N1 influenza outbreak in Hong Kong at the end of 1997 emphasised the need for viral surveillance so that new influenza epidemics can be foreseen. Although South China is regarded as the regional epicentre of influenza epidemics, there has been little epidemiological documentation of the disease there. A sentinel physician network was established in Hong Kong in 1993 to estimate the incidence, severity, and seasonality of influenza-like illnesses and to provide data on the demand for health care that is related to this illness. Influenza-like illness occurred throughout the year of the survey, peaking from March through May and accounting for 15% of doctor visits. The incidence was approximately 117 in 1000 patients and was greatest among children aged 1 to 4 years. Ongoing physician surveillance with appropriate coverage of the general population supported by a laboratory virus isolation capability may help control future influenza outbreaks.