Table 3.

Summary of large, prospective studies with sufficient follow up and laboratory confirmation of influenza outcomes.

Study	Population	Study design	Surveillance method	Dates of surveillance	Influenza detection	Outcome	Incidence rate of LRTI per 1000 person years	NOS
Neuzil et al. [26]	Children less than 5 years; Nashville TN, USA (n = 1665)	Prospective cohort study	Passive, children < 5 years old seeking care at clinic for acute respiratory illness	August 1, 1974- July 31 1999	Virus culture, HAI	Clinical diagnosis of lower respiratory tract disease	8 (5–12)	7
McMorrow et al. [27]	Children less than 5 years; Kenya (n = 8493)	Prospective household and clinic-based surveillance network	Active, bi-weekly or weekly home visits	2009–2012	RT-PCR	Acute respiratory infection with a subjective or measured temperature of ≥ 38 °C and cough with onset in the last 10 days requiring hospitalization plus physician diagnosed lower respiratory tract infection	17 (14–20)	8
Broor et al. [30]	Infants followed until 3 yrs old; Nepal (n = 281)	Prospective cohort study	Active, weekly home visits	October 1, 2001 – December 31 2004	DFA	WHO ICMI classification for acute lower respiratory disease	13 (0–69)	7