Data collection.

Data were gathered on precoded standardized questionnaire by trained community health-care workers (CHWs). Community health-care workers sequentially visited the households of children randomly selected from a sampling frame provided by surveillance system and administered the questionnaire. The primary respondent was the main caretaker or the mother. If the caretaker or the mother was absent, or the house was locked, three attempts were made to establish contact. In case contact could not be established or there was refusal to participate, the next child on the list was contacted. Information on household demographics and composition, occurrence of pneumonia, vaccination, air quality, and knowledge regarding preventive measures for pneumonia was collected. If caretaker recalled an incident of pneumonia in past 8 weeks, further questions were asked regarding specific symptoms such as fever, fast breathing, chest indrawing, and danger signs. Also, questions were asked regarding care seeking, use of drugs, outcome, and hospitalization. If the child did not experience the disease or related symptoms in the past 8 weeks, hypothetical questions were asked about anticipated health-care use in case the child developed such an illness.