ObjectiveTo develop an early warning index system to identify the outbreak of respiratory infectious diseases and to assess the epidemic risk of these diseases in Shanghai.

MethodsA two-round Delphi survey with a panel of 31 experts was used to select the modifying indicators. All indicators were evaluated for necessity，feasibility，stability， and sensitivity through online questionnaires.

ResultsThe consultation recovery rates of both rounds were 100%. The authority coefficient was 0.88， and the Kendall's W of the second-round consultation was 0.138 （P<0.001）， suggesting a good coordination among experts’ opinion. Our early warning index system was developed after the two-round Delphi survey and included two sets of indicators， one for rapid risk assessment and another for monitoring and tracing risk. Both sets of the indicators involved three aspects： transmissibility， clinical severity and potential influence of emerging diseases. The rapid risk assessment system part covered 10 indicators while the risk monitor system part covered 23 indicators. In the rapid risk assessment system part， the weight value of the top three indicators were greater than 0.10， with the highest weight value of 0.171 for titled visiting rate of influenza-like illness patients in the Emergency Department or other outpatient visits. In the risk monitor system part， the weight value of the top eight indicators were greater than 0.05， and the greatest was 0.087 for R₀ （basic reproductive number）.

ConclusionThe developed scientific and reliable evaluation indicator system can be used to forecast the outbreak and epidemic risk of respiratory infectious diseases. However， sensitivity and stability of the indicators need further validation and evaluation.