Table 3.

Effectiveness of the 2011 and 2012 Southern Hemisphere influenza vaccines in various scenarios

		2011 Southern Hemisphere vaccine		2012 Southern Hemisphere vaccine
Scenario	Vaccination status	Vaccine effectiveness	95% confidence interval	Vaccine effectiveness	95% confidence interval
Adjust for age at ARI (continuous variable) and the presence of underlying medical condition	Full	57	–46, 87	64	12, 85
Exclude ARI episodes occurring during the last 6 months of season	Full	55	–72, 88	64	13, 85
Exclude all ARI episodes in persons treated with oseltamivir before swab collection	Full	75	–53, 96	57	–31, 86
Exclude ARI episodes that tested positive for A(H3N2) in 2012–2013 season	Full	n/a	n/a	63	2, 86
Re-classify children with 1st 2 doses administered <28 days apart as fully vaccinated	Full	57	–67, 89	64	13, 85
Exclude episodes with specimens collected =7 days of illness onset	Full	78	–31, 96	61	50, 84
Shorten time between last vaccination and onset of illness from 14 to 7 days	Full	58	–64, 89	65	13, 86
Include only children aged <36 months	Full	46	–103, 86	79	29, 94
Include only children with ≤3 months between vaccination and ARI onset	Full	*	*	3	–154, 63
Include only children with =3–6 months between vaccination and ARI onset	Full	*	*	61	–12, 87
Include only children with =6–9 months between vaccination and ARI onset	Full	*	*	84	6, 97

ARI, acute respiratory illness; n/a, not applicable.

^*Could not be calculated due to small sample size.