Table 2. Seroprevalence of naturally acquired antibodies to pandemic influenza A(H1N1) 2009, New Zealand and Singapore, 2009.

Country	Sample Size	Study Population	% Seropositive
New Zealand4	1 696	1–4 years old	29.5
	171	5–19 years old	46.7
	148	20–39 years old	22.2
	206	40–59 years old	20.2
	221	60+ years old	24.8
	258	Primary HCWs	29.6
Singapore5	838	Community (21–75 years)	13.5
	1 213	Military personnel (males 18–19 years)	29.4
	558	Acute care hospital staff	6.5
	300	Staff and residents of long-term care facility	1.2

*HI titres > 40, HCWs = health care workers