BLOOD DONORS AND BLOOD COLLECTION Epidemiology of hepatitis B in Canadian blood donors Sheila F. O’Brien, Guoliang Xi, Wenli Fan, Qi-Long Yi, Margaret A. Fearon, Vito Scalia, and Mindy Goldman BACKGROUND: The residual risk of hepatitis B is higher than for other markers such as human immuno- deficiency virus and hepatitis C virus in nonendemic countries. Evaluating the potential for further risk reduc- tion requires a better understanding of the relationship between donor selection criteria, immigration from endemic countries, and public health vaccination strategies. STUDY DESIGN AND METHODS: Age and sex trends of hepatitis B surface antigen (HBsAg)-positive donors from 1997 to 2006 were analyzed using a Poisson model. All HBsAg-positive donors in 2005/2006 plus four matched control donors for every HBsAg-positive donor who participated were invited to participate in a risk factor interview and predictors of HBsAg positivity identified by logistic regression. A survey of 40,000 donors who did not react for all markers asked about vaccination history and country of birth. RESULTS: Most HBsAg-positive donations were from first-time donors (86%), have been decreasing in donors under the age of 30 (p < 0.01), and were corre- lated with geographic regions with more donors from higher-prevalence countries (p < 0001). Birth in a higher-prevalence country predicted HBsAg positivity (p < 0.01). Fifty-six percent of donors reported being vaccinated for hepatitis including approximately 80 percent of donors under age 30 who reported being vaccinated as part of regular school programs. CONCLUSION: HBsAg-positive donations are decreas- ing in donors under age 30, those most frequently vaccinated through provincial vaccination programs. HBsAg-positive donations largely reflect immigration from high-prevalence countries without other deferrable risk factors, mainly chronic cases that will be detected by current testing. Furthermore, risk of incident infec- tions should decrease with increasing vaccination rates in donors, especially the younger cohort now receiving universal vaccination. I n Canada testing for hepatitis B surface antigen (HBsAg) has been in place since 1972, and in 2005 testing for antibody to hepatitis B core antigen (anti- HBc) was implemented to further reduce the risk of potentially infectious donations from entering the blood supply. 1 The residual risk of infection from hepatitis B virus (HBV ) is higher than for hepatitis C virus (HCV ) and human immunodeficiency virus (HIV ) in Canada, 2 similar to many industrialized nations, 3-5 but evaluating the potential for further risk reduction requires a better understanding of the factors influencing the epidemiol- ogy of HBV in blood donors. Hepatitis B risk has some attributes in common with other transfusion-transmissible infections for which the blood is routinely screened, but also some important dif- ferences. For example, some behaviors that increase risk of HBV infections such as drug use and sex with a high-risk partner are the same, but others such as birth (or parent birth) in an endemic country tend to be more associated with HBV in blood donors 6,7 than with HCV 7,8 or HIV. Fur- thermore, unlike HIV and HCV, HBV can be prevented by vaccination so that the probability of transmission even in high-risk groups can be reduced. In Canada, immigration has been changing the ethnic composition of the population, such that the visible minority continues to increase, with the fastest growing immigrant populations being from countries where hepa- titis B is more prevalent. 9 Thus the changing ethnic com- position of the donor base in Canada and other countries From the Canadian Blood Services, Ottawa, Ontario; and the Departments of Epidemiology & Community Medicine and Pathology & Laboratory Medicine, University of Ottawa, Ottawa, Ontario; and the Department of Pathology & Laboratory Medicine, University of Toronto, Toronto, Ontario, Canada. Address reprint requests to: Sheila F. O’Brien, National Epi- demiology and Surveillance, Canadian Blood Services, 1800 Alta Vista Drive, Ottawa, Ontario, Canada K1G 4J5; e-mail: sheila.o’brien@blood.ca. Supported by Canadian Blood Services. Received for publication May 1, 2008; revision received May 16, 2008; and accepted May 18, 2008. doi: 10.1111/j.1537-2995.2008.01845.x TRANSFUSION 2008;48:2323-2330. Volume 48, November 2008 TRANSFUSION 2323