Table 1.

Summary of case definitions and included symptoms used for influenza surveillance

Case definition and its source	Fever	Cough	Sore throat	Difficulty breathing (history)	Nasal discharge/runny nose	Earache	Rapid breathing (examination)
Influenza‐Like Illness (ILI): Sudden onset of a fever over 38°C, and either cough or sore throat in the absence of other diagnoses : WHO 3	Yes	Yes	Yes	No	No	No	No
Severe Acute Respiratory Illness (SARI) in ≥5 year age: Sudden onset of Fever over 38°C and either cough or sore throat, shortness of breath or difficulty breathing, and requiring hospital admission: PAHO 4	Yes	Yes	Yes	Yes	No	No	No
Severe Acute Respiratory Illness (SARI) in <5 year age: Any child <5 years old clinically suspected of having Pneumonia or severe/very severe pneumonia, and requiring hospital admission: WHO – IMCI. 16	No	Yes	No	Yes	No	No	Yes
Acute Respiratory Infection (ARI): ≥1 of the following: cough (new or worsened), sore throat, difficulty breathing or nasal discharge: ECDC 5	No	Yes	Yes	Yes	Yes	No	No
Febrile Acute Respiratory Illness: Sudden onset of fever and one or more of cough, sore throat, difficulty breathing, runny nose, or ear ache	Yes	Yes	Yes	Yes	Yes	Yes	No
≥1 respiratory symptom: ≥1 of the following signs or symptoms: cough, earache, nasal discharge, difficulty breathing (history), rapid breathing (examination), and sore throat	No	Yes	Yes	Yes	Yes	Yes	Yes