Table 3. Weighted seroprevalence of 2009 pandemic H1N1 virus antibodies by demographic characteristics among subjects who reported not receiving pH1N1 vaccine (N = 42,300).

Demographic Characteristics	Samples tested	Positive samples	pH1N1antibody (%)	Weighted prevalence ofpH1N1 antibody (%)	95% Confidence Interval
Age group, years
0–5	9512	2550	26.8	24.7	22.4–26.9
6–15	7409	2677	36.1	32.9	30.2–35.6
16–24	7485	2369	31.6	30.3	27.7–32.9
25–59	8984	1255	14.0	10.7	9.5–12.0
≥60	8910	768	8.6	9.9	8.2–11.7
Gender
Male	20430	4893	24.0	18.2	16.7–19.6
Female	21870	4726	21.6	16.0	14.8–17.2
Occupation#
Children in family care	3088	662	21.4	20.8	17.6–24.1
Children in kindergarten	6763	1967	29.1	26.2	23.0–29.5
Student	9871	3785	38.3	34.9	32.5–37.3
Teacher	609	136	22.3	16.1	7.9–24.4
Doctor or nurse	1311	303	23.1	19.0	13.7–24.4
Other	20579	2751	13.4	11.1	10.1–12.1
Urban/rural
Capital city (Municipalities)	13321	3052	22.9	17.1	15.7–18.4
Other urban areas	13791	3333	24.2	19.6	18.2–21.1
Rural areas	15188	3234	21.3	15.7	14.4–17.0
Region
Eastern	15483	3301	21.3	15.2	13.8–16.7
Central	15276	3554	23.3	18.6	17.3–19.8
Western	11541	2764	23.9	19.3	17.7–20.9
Total	42300	9619	22.7	17.1	16.1–18.0

NOTE. # 79 unvaccinated participants were missing occupation data.