1. Control close contacts and sub-close contacts.

2. Seal and control places where close contacts and sub-close contacts pass.

3. Thoroughly disinfect items that come into contact with close contacts and sub-close contacts to cut off the transmission of infection to the greatest extent. Influenza investigation is the key to epidemic control. It provides the basis for delineating a clear chain of virus transmission, identifying close contacts, taking isolation measures, and delineating the scope of disinfection. Later epidemic investigation is mainly to trace the source and find out who was the original infector. source, take effective measures to control and completely eliminate the risk of spreading infectious diseases.