Table 1. Proportion of baseline sera reactive to pandemic influenza H1N1 (2009) virus in each age group, 2006–2008.

Age (years)	No. of Samples tested(n = 2379)	No. of positive samples	Proportion of positive antibody %	95%CI
0–5	436	0	0	0–0.7
6–15	556	6	1.1	0.4–2.3
16–24	360	12	3.3	1.7-5.8
25–59	534	3	0.6	0.1–1.6
60–	493	10	2.0	1.0–3.7