NACI Update on Hepatitis B Vaccine

Abstract

Background: Infant and adolescent hepatitis B (HB) immunization programs have been successfully implemented in all Canadian provinces and territories since the 1990s. Following the introduction of universal immunization programs, the incidence of HB has decreased in all age groups. However, the duration of protection against chronic infection, as measured by preserved T- and B-cell memory, remains unknown.

Objectives: To review the evidence on long-term protection against HB in adolescents who received routine immunization in infancy, determine the level of risk of HB infection in Canadians with diabetes and assess the timing of re-vaccination of individuals with immunocompromising conditions.

Methods: The National Advisory Committee on Immunization (NACI) Hepatitis Working Group reviewed key questions and performed an evidence review and synthesis. In consideration of the burden of illness to be prevented, the target population and issues related to safety, immunogenicity, efficacy and effectiveness of the vaccine, the group proposed recommendations for vaccine use to NACI. All evidence was rated and summarized in tables. NACI approved specific evidence‑based recommendations and elucidated the rationale and relevant considerations in the Statement update.

Results: In addition to the epidemiological data assessment, NACI reviewed evidence from efficacy and effectiveness studies with up to 30 years of follow-up data as well as data from 39 publications on immune response following the administration of a HB booster dose in individuals who were immunized as infants. Based on the conducted review, NACI did not find evidence that would support a change to its current recommendation that there is no need for routine booster immunization of individuals immunized in infancy and that there is no evidence to support preferential immunization schedules or routine immunization of individuals with diabetes.

Conclusion: NACI now recommends that following immunization of immunocompromised individuals, initial annual monitoring of HB antibody levels may be considered.

Introduction

In unvaccinated individuals, the risk of chronic hepatitis B (HB) infection varies with age. Up to 95% of infants, 50% of children less than five years of age and 10% of adolescents and adults will develop a chronic infection ^{Footnote 1}. Although protection following a completed primary schedule is believed to be long lasting, the exact duration is not known. Presence of T- and B-cell memory is required for long-term protection ^{Footnote 2Footnote 3Footnote 4Footnote 5Footnote 6Footnote 7}. Following the introduction of universal immunization programs in all Canadian provinces and territories in the 1990s, the incidence of HB has decreased in all age groups ^{Footnote 8}. A summary of the current recommendations for HB vaccine is available in the Canadian Immunization Guide ^{Footnote 9}.

National Advisory Committee on Immunization (NACI) is a committee of immunization experts from across Canada that provides ongoing medical, scientific and public health advice to the Public Health Agency of Canada (PHAC) on vaccines authorized for sale in Canada. The NACI Hepatitis Working Group consists of NACI members, liaison members and other vaccine experts who systematically review and synthesize available scientific and other technical information (e.g. disease burden, vaccine characteristics, unpublished study data) pertaining to specific questions or issues concerning hepatitis A and hepatitis B vaccines ^{Footnote 10}.

Methods

The Hepatitis Working Group reviewed key questions and performed a review and synthesis of evidence on long-term protection against HB in adolescents who received routine immunization in infancy and the timing for re-vaccination of people with immunocompromising conditions. The group also reviewed epidemiological data and research evidence to determine the level of risk of HB infection in Canadians with diabetes. In consideration of the burden of illness to be prevented, the target population, safety, immunogenicity, efficacy and effectiveness of the vaccine, the Hepatitis Working Group proposed recommendations for vaccine use to NACI. All evidence was rated and summarized in evidence tables. NACI approved specific evidence-based recommendations and elucidated the rationale and relevant considerations in the Statement Update.

Results

In 2013, there were 0.5 cases of acute HB infection per 100,000 population and 12 cases of chronic HB infection per 100,000 population reported through the Canadian Notifiable Disease Surveillance System (CNDSS) ^{Footnote 10}. According to Canadian Health Measures Survey (CHMS) data, the prevalence of present HB infection in individuals 14 to 79 years of age is estimated to be 0.4%, with the highest infection rate reported in non-white (1.8%) and the foreign-born (1.6%) populations ^{Footnote 11}.

Based on a review of studies with up to 30 years of data, NACI did not find evidence that would suggest reduced long-term vaccine effectiveness in individuals who were immunized as infants. In addition, NACI also reviewed 39 publications which reported data on immune memory following the administration of a HB challenge dose and did not find evidence that would support the need for a routine HB vaccine booster dose in routine immunization programs.

Based on the reviewed evidence, NACI issued four recommendations for the use of HB vaccines in Canada. (see Text box)

A complete review of evidence and full NACI recommendations on the use of HB vaccine are published in the NACI Statement Update ^{Footnote 10} and the hepatitis B vaccine chapter of the Canadian Immunization Guide ^{Footnote 9}.

Conclusion

NACI now recommends that, following immunization of immunocompromised individuals, initial annual monitoring of HB antibody levels may be considered.

Authors' statement

This statement was prepared by the Hepatitis Working Group: Henry B (Working Group Chair), Baclic O, Brophy J, Choudhri Y, Coleman G, Gilca V, Ismail S, Marchant-Short S, Pham-Huy A, Salvadori M, Warrington R

Conflict of interest

None.

Acknowledgements

NACI members: Gemmill I (Chair), Quach C (Vice-Chair), Dayneka N, Deeks S, Henry B, Marchant-Short S, Salvadori M, Sicard N, Vaudry W, Vinh D, Warrington R

Liaison representatives: Blake J (Society of Obstetricians and Gynaecologists of Canada), Brophy J (Canadian Association for Immunization Research and Evaluation), Cohn A (Centers for Disease Control and Prevention, United States), Cole T (Canadian Immunization Committee), Emili J (College of Family Physicians of Canada), Lavoie M (Council of Chief Medical Officers of Health), Mah C (Canadian Public Health Association), Moore D (Canadian Paediatric Society), Pham-Huy A (Association of Medical Microbiology and Infectious Disease Canada)

Ex-officio representatives: Barnes K (National Defence and the Canadian Armed Forces), Charos G (Centre for Immunization and Respiratory Infectious Diseases [CIRID], Public Health Agency of Canada [PHAC]), Coleman G (Biologics and Genetic Therapies Directorate, Health Canada [BGTD], HC), Gallivan J (Marketed Health Products Directorate [MHPD], HC), Pennock J (CIRID, PHAC), Wong T (First Nations and Inuit Health Branch [FNIHB], HC)

Funding

The work of NACI is supported by Public Health Agency of Canada.