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Considerations on the current universal vaccination policy against hepatitis A in Greece after recent outbreaks. PLoS One 2015; 10:e0116939. [PMID: 25590132 PMCID: PMC4295885 DOI: 10.1371/journal.pone.0116939] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 12/17/2014] [Indexed: 12/16/2022] Open
Abstract
Greece is the only European Union member state that in 2008 included hepatitis A (HAV) vaccine in the routine national childhood immunization program (NCIP). Given that the resources allocated to public health have dramatically decreased since 2008 and that Greece is a low endemicity country for the disease, the benefit from universal vaccination has been questioned. The aim of this paper is to summarize the available epidemiological data of the disease for 1982-2013, and discuss the effects of universal vaccination on disease morbidity. Descriptive analysis, ARIMA modeling and time series intervention analysis were conducted using surveillance data of acute HAV. A decreasing trend of HAV notification rate over the years was identified (p<0.001). However, universal vaccination (~ 80% vaccine coverage of children) had no significant effect on the annual number of reported cases (p = 0.261) and has resulted to a progressive increase of the average age of infection in the general population. The mean age of cases before the inclusion of the vaccine to NCIP (24.1 years, SD = 1.5) was significantly lower than the mean age of cases after 2008 (31.7 years, SD = 2.1) (p<0.001). In the last decade, one third of all reported cases were Roma (a population accounting for 1.5% of the country’s total population) and in 2013 three outbreaks with 16, 9 and 25 Roma cases respectively, were recorded, indicating the decreased effectiveness of the current immunization strategy in this group. Data suggest that universal vaccination may need to be re-considered. Probably a more cost effective approach would be to implement a program that will include: a) vaccination of high risk groups, b) universal vaccination of Roma children and improving conditions at Roma camps, c) education of the population and travel advice, and d) enhancement of the control measures to increase safety of shellfish and other foods.
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Momtaz H, Rahimi E, Hajian S, Momeni M. Prevalence of hepatitis A virus in sea food in Iran. ARQ BRAS MED VET ZOO 2012. [DOI: 10.1590/s0102-09352012000400015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The objective of this study was to determine the prevalence of Hepatitis A Virus (HAV) in sea food samples in the Isfahan and Shahrekord townships in Iran. From September 2010 to April 2011, a total of 300 samples of fresh fish, shrimp, crab and lobster were obtained from randomly selected retail stores in the Isfahan and Shahrekord townships in Iran. The samples were tested for the presence of HAV using a reverse transcriptase- polymerase chain reaction method. Out of the total number of samples examined, 8 (2.7%) were found to be positive for HAV. This virus was detected in 5% and 1.7% of fresh fish and shrimp, respectively. This study shows the importance of sea food as potential sources of HAV infection in people in Iran.
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Pham B, Chen MH, Tricco AC, Anonychuk A, Krahn M, Bauch CT. Use of a Catalytic Model to Estimate Hepatitis A Incidence in a Low-Endemicity Country. Med Decis Making 2011; 32:167-75. [DOI: 10.1177/0272989x11398489] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background. Evaluating the cost-effectiveness of vaccine programs with dynamic modeling requires accurate estimates of incidence over time. Because infectious diseases are often underreported, supplementary data and statistical analyses are required to estimate true incidence. This study estimates the true incidence of hepatitis A virus (HAV) infection in Canada using a catalytic model. Methods. A catalytic model was used to reconcile HAV seroprevalence data with the corresponding true cumulative risk of infection estimated from incidence data. Results. The average annual reported incidence was 6.2 cases per 100 000 from 1980 to 1989 and 7.7/100 000 from 1990 to 1999, indicating that Canada is a low-incidence country. The seroprevalence in Canadian-born individuals (n = 7 studies) was approximately 1%−8% in ages <20, 1%−11% in ages 20–29, 7%−29% in ages 30–39, and higher in older age groups. Between 1980 and 1995, the catalytic model estimated an average annual incidence of 60/100 000 (95% confidence interval, 33–524); approximately 7.73 (4.21–67.33) times the average annual reported incidence of 7.78/100 000. For a typical birth cohort of 403 434 Canadians born in 1990, the model predicted 32 750 HAV cases by age 39, with a corresponding seroprevalence of approximately 8.12% by the year 2029. Implications. Reliable estimates of true incidence of infectious disease are required for cost-effectiveness analysis of infectious disease programs. Catalytic models enable the synthesis of dispersed data, quantification of data limitations, and reconciliation of these limitations to estimate true incidence for economic evaluations.
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Affiliation(s)
- Ba’ Pham
- Toronto Health Economics and Technology Assessment Collaborative, University of Toronto, Toronto, Ontario, Canada (BP, MK)
- Department of Health Policy, Management and Evaluation, University of Toronto (BP, MK)
- Department of Biostatistics, University of Toronto (MHC)
- Toronto General Hospital, University Health Network, Toronto (MHC)
- Li Ka Shing Knowledge Institute of St Michael’s Hospital, Toronto (ACT)
| | - Maggie Hong Chen
- Toronto Health Economics and Technology Assessment Collaborative, University of Toronto, Toronto, Ontario, Canada (BP, MK)
- Department of Health Policy, Management and Evaluation, University of Toronto (BP, MK)
- Department of Biostatistics, University of Toronto (MHC)
- Toronto General Hospital, University Health Network, Toronto (MHC)
- Li Ka Shing Knowledge Institute of St Michael’s Hospital, Toronto (ACT)
| | - Andrea C. Tricco
- Toronto Health Economics and Technology Assessment Collaborative, University of Toronto, Toronto, Ontario, Canada (BP, MK)
- Department of Health Policy, Management and Evaluation, University of Toronto (BP, MK)
- Department of Biostatistics, University of Toronto (MHC)
- Toronto General Hospital, University Health Network, Toronto (MHC)
- Li Ka Shing Knowledge Institute of St Michael’s Hospital, Toronto (ACT)
| | - Andrea Anonychuk
- Toronto Health Economics and Technology Assessment Collaborative, University of Toronto, Toronto, Ontario, Canada (BP, MK)
- Department of Health Policy, Management and Evaluation, University of Toronto (BP, MK)
- Department of Biostatistics, University of Toronto (MHC)
- Toronto General Hospital, University Health Network, Toronto (MHC)
- Li Ka Shing Knowledge Institute of St Michael’s Hospital, Toronto (ACT)
| | - Murray Krahn
- Toronto Health Economics and Technology Assessment Collaborative, University of Toronto, Toronto, Ontario, Canada (BP, MK)
- Department of Health Policy, Management and Evaluation, University of Toronto (BP, MK)
- Department of Biostatistics, University of Toronto (MHC)
- Toronto General Hospital, University Health Network, Toronto (MHC)
- Li Ka Shing Knowledge Institute of St Michael’s Hospital, Toronto (ACT)
| | - Chris T. Bauch
- Toronto Health Economics and Technology Assessment Collaborative, University of Toronto, Toronto, Ontario, Canada (BP, MK)
- Department of Health Policy, Management and Evaluation, University of Toronto (BP, MK)
- Department of Biostatistics, University of Toronto (MHC)
- Toronto General Hospital, University Health Network, Toronto (MHC)
- Li Ka Shing Knowledge Institute of St Michael’s Hospital, Toronto (ACT)
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Amariei R, Willms AR, Bauch CT. The United States and Canada as a coupled epidemiological system: an example from hepatitis A. BMC Infect Dis 2008; 8:23. [PMID: 18307785 PMCID: PMC2292190 DOI: 10.1186/1471-2334-8-23] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2007] [Accepted: 02/28/2008] [Indexed: 11/23/2022] Open
Abstract
Background Hepatitis A (HA) is a low-incidence, non-endemic disease in Canada and the United States (US). However, a large difference in HA incidence between Canada and HA-endemic countries has made travel an important contributor to hepatitis A prevalence in Canada. There is also a (smaller) incidence differential between Canada and the US. Although the US has only moderately higher HA incidence, the volume of travel by Canadians to the US is many times higher than travel volume to endemic countries. Hence, travel to the US may constitute a source of low to moderate risk for Canadian travelers. To our knowledge, travel to the US has never been included as a potential risk factor for HA infection in Canadian epidemiologic analyses. The objective of this study was to use dynamic models to investigate the possible effects on hepatitis A incidence in Canada due to (1) implementing vaccination in the US, and (2) varying the volume of travel by Canadians to the US. Methods We developed and analyzed age-structured compartmental models for the transmission and vaccination of hepatitis A, for both Canada and the US. Models were parameterized using data on seroprevalence, case reporting, and travel patterns. The potential effect of hepatitis A prevalence in the US on hepatitis A prevalence in Canada was captured through a term representing infection of Canadians due to travel in the US. Results The model suggests that approximately 22% of HA cases in Canada in the mid 1990s may have been attributable to travel to the US. A universal vaccination programme that attained 70% coverage in young children in the US in the mid 1990s could have reduced Canadian incidence by 21% within 5 years. Conclusion Since not all necessary data were available to parameterize the model, the results should be considered exploratory. However, the analysis shows that, under plausible assumptions, the US may be more important for determining HA prevalence in Canada than is currently supposed. As international travel continues to grow, making vaccination policies ever more relevant to populations beyond a country's borders, such multi-country models will most likely come into wider use as predictive aids for policy development.
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Affiliation(s)
- Raluca Amariei
- Department of Mathematics and Statistics, The University of Guelph, Guelph, Canada.
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Cost-utility of universal hepatitis A vaccination in Canada. Vaccine 2007; 25:8536-48. [DOI: 10.1016/j.vaccine.2007.10.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2007] [Revised: 10/02/2007] [Accepted: 10/02/2007] [Indexed: 11/19/2022]
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Soysal A, Gokçe I, Pehlivan T, Bakir M. Interchangeability of a hepatitis A vaccine second dose: Avaxim 80 following a first dose of Vaqta 25 or Havrix 720 in children in Turkey. Eur J Pediatr 2007; 166:533-9. [PMID: 17318620 DOI: 10.1007/s00431-007-0432-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2006] [Revised: 01/17/2007] [Accepted: 01/18/2007] [Indexed: 10/23/2022]
Abstract
INTRODUCTION This randomised, observer-blind clinical trial conducted in Turkey evaluated the immunogenicity, safety and interchangeability of three paediatric inactivated hepatitis A vaccines in 424 seronegative children between 1 and 15 years of age. METHODS Potential subjects were screened for anti-hepatitis A virus (HAV) antibodies prior to receiving a first dose of Avaxim 80, Havrix 720 or Vaqta 25, followed by a second dose of either the same vaccine or Avaxim 6 months later. Anti-HAV antibody concentrations were measured 2 weeks after the first injection, at 24 weeks (before the second dose) and at 28 weeks for the evaluation of the immune response. RESULTS Nearly 80% of the children between 1 and 5 years of age and half of those between the ages of 6 and 10 in the population from which the subjects were recruited were seronegative for HAV antibodies. Two weeks after the first dose, 98.2% of all subjects had anti-HAV antibody concentrations equal to or higher than 20 mIU/mL, believed to be seroprotective, and all subjects were seroprotected before and after the second dose. Anti-HAV geometric mean concentrations (GMCs) 2 weeks after the first dose and before the second were similar in children who received Avaxim and Vaqta (P = 0.2), but both were higher than Havrix (P < 0.01). There were no significant differences in the anti-HAV GMCs between the study groups that received two doses of the same vaccine compared with two doses of different vaccines. There were no significant differences in the frequency of any local or systemic adverse events among the study groups following either of the two doses. CONCLUSION All three vaccines are safe and highly immunogenic in healthy children aged 1 to 15 years. Avaxim 80 may also be given as the second dose when Havrix 720 or Vaqta 25 are given as the first dose. The pattern of seroprevalence seen here is similar to that reported in a number of recent evaluations in Turkey, and are supportive of the routine hepatitis A vaccination of young children.
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Affiliation(s)
- Ahmet Soysal
- Department of Paediatric Infectious Diseases, Marmara University Medical School, Tophanelioğlu Caddesi, Altunizade, Istanbul, Turkey
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Bauch CT, Rao ASRS, Pham BZ, Krahn M, Gilca V, Duval B, Chen MH, Tricco AC. A dynamic model for assessing universal Hepatitis A vaccination in Canada. Vaccine 2007; 25:1719-26. [PMID: 17229493 DOI: 10.1016/j.vaccine.2006.11.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Accepted: 11/13/2006] [Indexed: 10/23/2022]
Abstract
Vaccination against Hepatitis A virus (HAV) in Canada is currently targeted toward high-risk groups. However, universal vaccination has been adopted in several other countries with a similar disease burden. Here we develop an age-structured compartmental model of HAV transmission and vaccination in Canada to assess potential universal vaccination strategies. The model predicts that universal vaccination at age 1 (respectively 4, 9, 15), with phasing out of targeted vaccination, would reduce reported incidence by 60% (respectively 52, 36, 31%) and mortality attributable to HAV by 56% (respectively 45, 26, 25%), relative to continued targeted vaccination, over 80 years.
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Affiliation(s)
- C T Bauch
- Department of Mathematics and Statistics, University of Guelph, Canada.
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Abstract
When first introduced in 1992 the hepatitis A vaccine was recommended for individuals at high risk of exposure. This policy was not expected to have a significant impact on disease incidence at population level in view of the epidemiology of the hepatitis A virus (HAV). More recently two countries, Israel and Bahrain, and regions or subpopulations in others (Australia, China, Byelorussia, Italy, Spain, US) have embarked upon more ambitious vaccination programmes that aim to immunize whole birth cohorts. After a brief survey of the virology and epidemiology of HAV, the disease burden it inflicts and a short history of the development of HAV vaccines--both live (in China) and killed vaccines are available--he vaccination programmes introduced in the countries mentioned above are described. The results have been spectacular: disease incidence, not only in the vaccinated cohorts but also in the whole population, have plummeted within a few years of the start of mass vaccination. There is now convincing evidence that the vaccine confers herd immunity if the main spreaders of the virus are targeted for immunization. This finding should encourage other countries to start mass vaccination programmes against HAV, particularly as pharmacoeconomic studies are beginning to show that such a strategy could be a cost-effective way of controlling the disease. It is now even conceivable to eradicate HAV. In fact, this should be easier to achieve than polio eradication as HAV vaccines confer more durable immunity than polio vaccines. However, the global disease burden of HAV is generally thought not to be high enough to justify such an undertaking in the foreseeable future.
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Tricco AC, Pham B, Duval B, De Serres G, Gilca V, Vrbova L, Anonychuk A, Krahn M, Moher D. A review of interventions triggered by hepatitis A infected food-handlers in Canada. BMC Health Serv Res 2006; 6:157. [PMID: 17156461 PMCID: PMC1702355 DOI: 10.1186/1472-6963-6-157] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2006] [Accepted: 12/08/2006] [Indexed: 01/17/2023] Open
Abstract
Background In countries with low hepatitis A (HA) endemicity, infected food handlers are the source of most reported foodborne outbreaks. In Canada, accessible data repositories of infected food handler incidents are not available. We undertook a systematic review of such incidents to evaluate the extent of viral transmission through food contamination and the scope of post-exposure prophylaxis (PEP) interventions. Methods A systematic search of MEDLINE and EMBASE was conducted to identify published reports of incidents in Canada. An expanded search of a news repository (i.e., transcripts from newspapers and newscasts) was also conducted to identify the location and timing of an incident, which was used to retrieve the related report by contacting local public health departments. Data pertaining to case identification, public health risk, PEP interventions, and associated costs was independently abstracted by two reviewers and summarized according to incidents with and without large PEP interventions. Results A total of 16 incidents were identified from 1998–2004. There were approximately 3 incidents requiring public notification per year. Only 12.5% of incidents were described in published reports, indicating that published data significantly underestimated the number of incidents and PEP interventions. Data pertaining to the remaining incidents was unpublished, sparse and highly dispersed at the local public health level. Six of the 16 incidents required large PEP interventions to immunize on average 5000 potentially exposed individuals. Secondary transmission was low. Characteristics of incidents requiring large PEP interventions included potentially infectious food handlers working with uncooked food for a prolonged duration in high-volume grocery stores in high-density urban areas. Conclusion Infected food handlers with hepatitis A virus (HAV) requiring public notification are not infrequent in Canada. Published data severely underestimated the burden of PEP intervention. Better and consistent reporting at the local and national level as well as a national data repository should be considered for the management of future incidents.
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Affiliation(s)
- Andrea C Tricco
- Epidemiology and Biostatistics, GlaxoSmithKline Canada, Mississauga, Ontario, Canada
- Chalmers Research Group, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada
- Institute of Population Health, Ottawa, Ontario, Canada
| | - Ba' Pham
- Epidemiology and Biostatistics, GlaxoSmithKline Canada, Mississauga, Ontario, Canada
- Chalmers Research Group, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada
- Department of Health Policy, Management and Evaluation, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Bernard Duval
- Centre de Recherche du CHUQ, Universite Laval, Institut national de santé publique du Québec, Canada
| | - Gaston De Serres
- Centre de Recherche du CHUQ, Universite Laval, Institut national de santé publique du Québec, Canada
| | - Vladimir Gilca
- Centre de Recherche du CHUQ, Universite Laval, Institut national de santé publique du Québec, Canada
| | - Linda Vrbova
- University of British Columbia, Department of Health Care and Epidemiology, Vancouver, British Columbia, Canada
| | - Andrea Anonychuk
- Epidemiology and Biostatistics, GlaxoSmithKline Canada, Mississauga, Ontario, Canada
- Division of Clinical Decision Making, Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Murray Krahn
- Department of Health Policy, Management and Evaluation, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Division of Clinical Decision Making, Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada
| | - David Moher
- Chalmers Research Group, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada
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Cohort effects in dynamic models and their impact on vaccination programmes: an example from hepatitis A. BMC Infect Dis 2006; 6:174. [PMID: 17147828 PMCID: PMC1702544 DOI: 10.1186/1471-2334-6-174] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2006] [Accepted: 12/05/2006] [Indexed: 01/17/2023] Open
Abstract
Background Infection rates for many infectious diseases have declined over the past century. This has created a cohort effect, whereby older individuals experienced a higher infection rate in their past than younger individuals do now. As a result, age-stratified seroprevalence profiles often differ from what would be expected from constant infection rates. Methods Here, we account for the cohort effect by fitting an age-structured compartmental model with declining transmission rates to Hepatitis A seroprevalence data for Canadian-born individuals. We compare the predicted impact of universal vaccination with and without including the cohort effect in the dynamic model. Results We find that Hepatitis A transmissibility has declined by a factor of 2.8 since the early twentieth century. When the cohort effect is not included in the model, incidence and mortality both with and without vaccination are significantly over-predicted. Incidence (respectively mortality) over a 20 year period of universal vaccination is 34% (respectively 90%) higher than if the cohort effect is included. The percentage reduction in incidence and mortality due to vaccination are also over-predicted when the cohort effect is not included. Similar effects are likely for many other infectious diseases where infection rates have declined significantly over past decades and where immunity is lifelong. Conclusion Failure to account for cohort effects has implications for interpreting seroprevalence data and predicting the impact of vaccination programmes with dynamic models. Cohort effects should be included in dynamic modelling studies whenever applicable.
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Abstract
PURPOSE OF REVIEW Current issues in immunization against hepatitis A and B are discussed, including the need to abandon risk-based approaches in favour of universal vaccination, the use of combined hepatitis A and B vaccines and multivalent vaccines, the development of third-generation triple antigen hepatitis B vaccines and polyvalent vaccines. RECENT FINDINGS The emergence of hepatitis B surface antigen mutants remains a concern in diagnostic work and immunoprophylaxis and horizontal transmission of the G145R variant stresses the need for surveillance programmes. The more recent and unfounded concerns about the safety of hepatitis B vaccines are noted. Innovative approaches to vaccine production including DNA vaccines and the expression of hepatitis B antigen components in plants (edible vaccines) are reviewed. SUMMARY This review describes further evidence to support the introduction of universal immunization against hepatitis B in those countries where this has yet to be implemented. Immunization programmes will continue to evolve to include the administration of polyvalent vaccines in order to best protect populations against infectious diseases.
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Affiliation(s)
- Jane N Zuckerman
- Academic Centre for Travel Medicine & Vaccines and the WHO Collaborating Centre for Reference, Research & Training in Travel Medicine, Royal Free & University College Medical School, London, UK.
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Mutsch M, Spicher VM, Gut C, Steffen R. Hepatitis A Virus Infections in Travelers, 1988-2004. Clin Infect Dis 2006; 42:490-7. [PMID: 16421793 DOI: 10.1086/499816] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2005] [Accepted: 11/10/2005] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Uncertainty exists about the current risk of hepatitis A virus infection in nonimmune travelers to destinations with high or intermediate risk of transmission. We analyzed recent epidemiological data on imported hepatitis A to determine region-specific attack rates and incidences. METHODS Surveillance data on hepatitis A virus infections diagnosed during 1988-2004 were evaluated on the basis of notification by laboratories, additional reports of physicians, and traveler's statistics. This study focuses on international travelers with hepatitis A virus infection detected after their return to Switzerland. RESULTS The rate of imported hepatitis A virus infections decreased 75% from 1988 to 2004 and accounted overall for 42% of all hepatitis A cases reported in Switzerland. The actual incidence of hepatitis A in travelers to countries of high or intermediate risk of transmission was 3.0-11.0 per 100,000 person-months abroad for all travelers and 6.0-28.0 per 100,000 for those presumed to be nonimmune. The actual proportion of those visiting friends and relatives among patients with hepatitis A has increased to 28.2%, with children aged 0-14 years predominating. Reductions in the incidence by hepatitis A vaccination were estimated to vary between 35.0% and 61.8% for different destinations. CONCLUSIONS The risk of hepatitis A virus infections has decreased by a factor of 10-50-fold over time, compared with findings from older studies. The risk, however, remains very considerable at many destinations, including frequently visited places, such as Mexico. Children of immigrants are a high-risk population. Strategies are needed to reach those at highest risk.
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Affiliation(s)
- Margot Mutsch
- Division of Epidemiology and Prevention of Communicable Diseases, World Health Organization Collaborating Centre for Travelers' Health, Institute of Social and Preventive Medicine, University of Zurich, Zurich, Switzerland.
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Pham B, Duval B, De Serres G, Gilca V, Tricco AC, Ochnio J, Scheifele DW. Seroprevalence of hepatitis A infection in a low endemicity country: a systematic review. BMC Infect Dis 2005; 5:56. [PMID: 16001978 PMCID: PMC1183208 DOI: 10.1186/1471-2334-5-56] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2005] [Accepted: 07/07/2005] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND In Canada--a low endemicity country, vaccines for hepatitis A virus (HAV) are currently recommended to individuals at increased risk for infection or its complications. Applying these recommendations is difficult because the epidemiology of HAV infection is poorly defined, complex, and changing. This systematic review aimed to 1) estimate age-specific prevalence of HAV antibody in Canada and 2) evaluate infection-associated risk factors. METHODS MEDLINE (1966-2005) and EMBASE (1980-2005) were searched to identify relevant studies for the systematic review. Archives for the Canada Diseases Weekly Report (1975-1991) and Canada Communicable Disease Report (1992-2005) were searched for relevant public health reports. Data were abstracted for study and participants' characteristics, age-specific prevalence, and risk factors. RESULTS A total of 36 reports describing 34 unique studies were included.The seroprevalence in Canadian-born children was approximately 1% in ages 8-13, 1-6% in 20-24, 10% in 25-29, 17% in 30-39, and increased subsequently. In age groups below 20 and 20-29, age-specific seroprevalence generally remained constant for studies conducted across geographic areas and over time. Compared to Canadian-born individuals, subjects born outside Canada were approximately 6 times more likely to be seropositive (relative risk: 5.7 [95% CI 3.6, 9.0]). Travel to high risk areas in individuals aged 20-39 was associated with a significant increase in anti-HAV seropositivity (RR 2.8 [1.4, 5.5]). Compared to heterosexuals, men having sex with men were only at a marginally higher risk (adjusted odds ratio 2.4 [0.9, 6.1]). High risk for seropositivity was also observed for Canadian First Nations and Inuit populations. CONCLUSION Results from the current systematic review show that in this low endemicity country, disease acquisition occurs in adulthood rather than childhood. The burden of disease is high; approximately 1 in 10 Canadians had been infected by ages 24-29. The increase in prevalence in young adults coincides with disease importation and increasing frequency of risk factors, most likely behavioral-related ones. Gaps in seroprevalence data were identified rendering the application of current immunization recommendations difficult. A nationwide prevalence survey for all Canadians is needed. This is essential to quantify the effectiveness of current recommendations and conduct cost-effectiveness evaluations of alternative immunization programs, if necessary.
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Affiliation(s)
- Ba' Pham
- BioMedical Data Sciences, GlaxoSmithKline, Ontario, Canada
- Chalmers Research Group, Children's Hospital of Eastern Ontario Research Institute, Ontario, Canada
| | - Bernard Duval
- Centre De Recherche du CHUQ, Institut Nationale Sante Publique du Quebec, Quebec, Canada
| | - Gaston De Serres
- Centre De Recherche du CHUQ, Institut Nationale Sante Publique du Quebec, Quebec, Canada
| | | | | | - Jan Ochnio
- Vaccine Evaluation Centre, University of British Columbia, British Columbia, Canada
| | - David W Scheifele
- Vaccine Evaluation Centre, University of British Columbia, British Columbia, Canada
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