Ineffectiveness of the Current Strategy to Prevent Hepatitis A in Travelers

BACKGROUND: Each year, a large number of Canadians travel to regions of the world where hepatitis A remains endemic. Many of these travelers are not immune and the current preventive strategy relies wholly on self-referral to a travel clinic. All of the costs associated with such a visit are assumed by the traveler. We estimated the effectiveness of this strategy. METHODS: This case-control study included 108 travel-related hepatitis A cases with onset of disease between 1997 and 1999 and 620 controls who traveled during the same period. RESULTS: Hepatitis A was strongly associated with high-risk travel (Odds Ratio = 7.2, 95% Confidence Interval 1.76-29.4), but only 7% of cases were found in this category. The risk of hepatitis A was 5 times lower in travelers who visited a travel clinic than in those who did not (80% efficacy). However, only 14% of the controls visited a travel clinic. As a result, the effectiveness of the current strategy is estimated to be 11% (80% of 14%). CONCLUSIONS: Hepatitis A in travelers can be prevented effectively by attendance at a travel clinic. Unfortunately, most travelers do not visit such clinics prior to departure. Even if all high-risk travelers were to visit a travel clinic and receive vaccination, this would have negligible impact on the number of travel-related hepatitis A cases (approximately 7% reduction). The current strategy for the prevention of hepatitis A in travelers is ineffective and should be reexamined.