According to university statistics compiled for Fall 2007, there were 23,499 undergraduate students at the university, among which 9,618 students (42%) identified themselves as an A/PI ethnicity. 612 students responded to the first email invitation and 604 students who did not respond to the first email responded to the second email invitation (). Between November 1, 2007 and November 24, 2008, 311 students were enrolled in the study; complete serologic, demographic and questionnaire data were available on 304 students.
Study design, recruitment and enrollment of Asian and Pacific Islander undergraduate university students for the study of HBsAg seroprevalence.
Of the enrolled subjects with complete data (n=304), 145 (47.70%) were born in the US and 159 (52.30%) were born in foreign countries ( and ). Seven of the foreign-born students were born in non-A/PI countries including Australia (2), Brazil (1), Canada (1), England (1), Germany (1), and Saudi Arabia (1) and were excluded from analysis. Among the US-born students, 121 (83.45%) were born to immigrant mothers, all from Asian countries or the Pacific Islands. There was no statistically significant difference in gender between the US-born and A/PI-born groups (63% female versus 63% female, respectively, p = 0.90). Note that females comprise 56% of the total undergraduate population, but the gender distribution in the population of A/PI undergraduate students is not available. The mean (+/− standard deviation) age of US-born (19.5 ± 1.3 y) was significantly lower than of A/PI-born students (20.6 ± 2.8, P<0.0001).
Comparison of HB seropositivity and Vaccination Status in US-born to Asia/Pacific Islander-born students
Overall, nearly one-third of all students (32.9%) reported that they did not know if they had received the HBV vaccine. There was no statistically significant difference (P = 0.7) in self-reported HBV vaccination between the US-born (69.7%, C.I. = 61.5%, 77.0%) and A/PI-born (64.5%, C.I. = 56.3%, 72.1%) groups.
Of the total sample, 7 students (2.3%) tested positive for HBsAg: 2 students from the US-born group (1.4%, C.I. = 0.0%, 3.3%) and 5 from the A/PI-born group (3.3%, C.I. = 0.5%, 6.1%). Both HBsAg-positive US-born students were born of immigrant mothers (Korea and Vietnam, respectively), giving a prevalence of 1.7% (C.I. = 0.0%, 3.9%) among US-born students born of immigrant mothers (). Of the five A/PI-born HBsAg-positive students, one was born in China and four in Vietnam. There was no statistically significant difference in HBsAg prevalence between the US-born group and the A/PI-born group (P = 0.45). Of the 7 HBsAg seropositive students, 4 recalled having received the HBV vaccine.
Prevalence rates of HBsAg in University Undergraduate Students in California, USA
Simple logistic regression did not reveal any significant associations between HBsAg positivity and country of birth, gender, age, or parents’ country of birth. Presence of HBsAg was negatively associated with reported HBV vaccination (OR 0.03, P = 0.01). In other words, a reported lack of HBV vaccination was associated with an increased risk of testing positive for HBsAg.