Abstract
In British Columbia (BC), hepatitis A virus (HAV) and hepatitis B virus (HBV) vaccines are provincially funded for persons with chronic hepatitis infections. To assess the effectiveness of BC public health follow-up of HBV and hepatitis C virus (HCV) cases and immunization policy by determining the number of vaccine-preventable acute hepatitis infections reported following a chronic HBV or HCV diagnosis, by examining demographic characteristics and by observing temporal trends. All newly identified cases of HAV, HBV and HCV between 1991 and October 2007 were extracted from the BC integrated Public Health Information System and linked to ascertain cases of hepatitis suprainfection. Between 1991 and October 2007, 30 BC residents with chronic HBV and 104 with HCV were subsequently diagnosed with HAV. Acute HBV was identified in 162 persons previously diagnosed with HCV. Significantly more men than women developed hepatitis suprainfection (P<0.0001), but women were of a younger age when they were diagnosed with HAV (P=0.02) and acute HBV (P=0.0002). HAV suprainfection cases among those with HCV peaked in 1998 at 33 cases and declined to zero cases in 2007. In comparison, HBV suprainfection among individuals with chronic HCV peaked in 1996 at 26 cases and declined to two cases in 2007. Cases of HAV and acute HBV have declined among HCV-infected individuals. However, despite the availability of publicly funded vaccines for high-risk groups, a substantial number of acute HBV infections post-HCV identification are still identified, indicating that follow-up and vaccination coverage should be improved in these populations.
Highlights
BACkgrounD: In British Columbia (BC), hepatitis A virus (HAV) and hepatitis B virus (HBV) vaccines are provincially funded for persons with chronic hepatitis infections
Transmission routes for hepatitis B virus (HBV) and hepatitis C virus (HCV) may be similar [7] in Canada, HBV is mainly transmitted sexually [8] whereas HCV is primarily transmitted parenterally, with the majority of incident and prevalent HCV infections occurring among injection drug users (IDUs) [3,9,10,11]
People with chronic viral hepatitis who become acutely infected with HAV or HBV are at an increased risk of liver failure [12]; chronic HBV and HCV coinfection is associated with poorer outcomes and an accelerated progression of liver disease [7,13,14,15]
Summary
Data cleaning removed a total of 90 cases; the majority were excluded to ensure temporality (ie, acute HAV or HBV diagnosis occurred after chronic hepatitis diagnosis [not before or within 14 days]). Between 1991 and October 2007, 30 BC residents with chronic HBV and 104 with HCV were subsequently reported to be infected with HAV (Table 1); of these, 13 had HAV after both chronic HBV and HCV. During this period, the overall cumulative population rate of HAV suprainfection identification was 3.1 per 100,000. The cumulative identification rate for individuals diagnosed with HAV alone was 82.3 per 100,000, and the mean age at diagnosis was significantly younger than the suprainfected cases – 31.6 years (95% CI 31.1 to 32.2) versus 35.9 years (95% CI 33.9 to 37.8). Reported cases of HAV were declining before publicly funded immunization programs for high-risk groups, from 900 cases in 1992 to 478 cases in 2006; since
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