Table 1.

Seroprevalence of varicella in American Samoa for elementary and college students, 2011, by selected variables

Variable	Elementary school students			College students
	No. of students	Seroprevalence, % (95% CI)	P value	No. of students	Seroprevalence, % (95% CI)	P value
Sex*			0·454			1·000
Female	258	77·5 (72·4–82·6)		127	96·1 (92·7–99·5)
Male	248	81·9 (77·1–86·7)		73	97·3 (93·5–100·0)
Age (years)†			0·388			1·000
4–6	304	76·0 (73·3–82·6)		n.a.	n.a.
7–9	205	79·5 (75·6–86·4)		n.a.	n.a.
17–19	n.a.	n.a.		80	97·5 (94·1–100·0)
20–22	n.a.	n.a.		83	96·4 (92·4–100·0)
⩾23	n.a.	n.a.		43	97·7 (93·2–100·0)
Region‡			0·093			0·672
Central	91	73·6 (63·4–82·3)		58	96·6 (88·1–99·6)
East	68	83·8 (72·9–91·6)		26	96·2 (80·4–100·0)
Midwest	249	80·3 (74·8–85·1)		86	95·4 (88·5–98·7)
West	105	70·5 (60·8–79·0)		37	100·00 (90·5–100·0)
Place of birth§			0·277
American Samoa (AS)	463	77·5 (73·5–81·3)		n.a.	n.a.
Outside AS∥	21	90·5 (69·6–98·8)		n.a.	n.a.
History of varicella disease			< 0·001			1·000
No	247	63·6 (57·2–69·6)		66	97·0 (89·5–100·0)
Yes	211	93·4 (89·1–96·3)		127	97·6 (93·3–100·0)
Documented history of one dose of varicella vaccine			0·141			1·000
Yes	18	94·4 (72·7–100·0)		1	100·0 (2·5–100·0)
No	467	77·5 (73·5–81·2)		149	98·0 (94·2–100·0)

CI, Confidence interval; n.a., not available.

^*Excludes 16 students with missing information on gender.

^†Excludes eight students with missing information on birth date or date of serum collection. No data were available on children aged 10–16 years.

^‡Excludes one student with missing information on region.

^§Place of birth was only available for 484 elementary school students.

^∥Eighteen students were born in the USA, one student was born in Marshall Islands, one student was born in Australia, and one student in Tonga.