Few data are available concerning the persistence of anti-HBs and the effect of booster doses given several years post-vaccination against hepatitis B during preadolescence. The objective of this open-labelled clinical trial was to evaluate the persistence of antibodies after vaccination with three paediatric doses of Engerix-B at the age of 8-10 years and the effect of a booster dose given 5 (Group Y5) or 10 (Group Y10) years later. Anti-HBs were measured before and one month post-primary vaccination, then 5 and 10 years later, before the booster dose, as well as one month and 1 year post-booster. The anamnestic response was defined as a >or=fourfold increase of anti-HBs post-booster (>or=10 IU/L) when compared to pre-booster. Ten years post-primary vaccination, 559 of the 652 initially randomized subjects (86%) were eligible for analysis. Group Y5, 5 years post-booster results: 99% of subjects had detectable levels of antibodies and 96% a titer >or=10 IU/L. The anti-HBs GMTs decreased from 114,489 IU/L one month post-booster to 3354 IU/L 5 years later. Group Y10 results: 10 years post-primary vaccination 96% of subjects had a detectable level of anti-HBs and 85% were above the threshold of 10 IU/L. The GMTs one month post-booster were 31,030 IU/L. The challenge with a booster demonstrated an anamnestic response in 99% of subjects in group Y5 and 100% of subjects in group Y10. All subjects were anti-HBc negative. The booster doses were well tolerated. The excellent anamnestic response observed after the booster dose demonstrates the persistence of immunity in virtually all young adults vaccinated at the age of 8-10 with three paediatric doses of Engerix-B.
We assessed the scientific basis and practical implications of recommendations made since the late 1990s to offer rabies postexposure prophylaxis (RPEP) for occult bat encounters, including recommendations to offer RPEP to persons with bedroom exposure to a bat while sleeping without evidence of direct physical contact.
The number needed to treat after bedroom exposure to a bat was calculated as the percentage of population exposed multiplied by the inverse of crude rabies incidence. Bedroom exposure was estimated in a population survey of 14,453 households. Incidence was based on reported human cases in Canada and the United States, 1990-2007.
In the population surveyed, bedroom bat exposure while sleeping and without known physical contact occurred at an annual rate of 0.099%. We estimate that
In response to concerns about interactions of academic and public health investigators with industry, the Canadian Association for Immunization Research and Evaluation (CAIRE), in collaboration with six major vaccine manufacturers, developed guidelines for participation in industry-sponsored clinical trial and epidemiology contract research within Canada. Topics addressed include definition of investigators, data ownership, protocol development, data management, data analysis, producing a study report and publication of the results of the study.
This paper is a report of a survey: (1) to document nurses' knowledge, attitudes and information needs regarding human papillomavirus prevention and (2) to determine factors associated with their willingness to recommend human papillomavirus vaccines.
Persistent infection with human papillomavirus has been causally linked to cervical cancer. Two human papillomavirus vaccines have recently been approved for use in more than 65 countries. Nurses' level of support for the prevention of human papillomavirus related diseases by vaccination has not been researched.
A survey was conducted in 2007. Self-administered questionnaires were mailed to 1799 randomly selected nurses. Descriptive statistics were generated for all variables. Multivariable logistic regression models were estimated to determine variables associated with the willingness to recommend human papillomavirus vaccines.
A total of 946 questionnaires were analyzed and showed that: 97% of nurses perceived routinely recommended vaccines as very useful; 93% would support human papillomavirus vaccination if it is publicly funded; 85% would recommend human papillomavirus vaccines to their patients; 33%, 46% and 61% expect the vaccination to permit screening to begin later in life, reduction of the frequency of screening, and reduction of the number of postscreening interventions, respectively. Respondents' knowledge score was 3.8 out of 7. Several modifiable factors, including knowledge, perceived self-efficacy, and societal and colleagues support were associated with willingness to recommend vaccines.
Most nurses' support human papillomavirus vaccination, but their active involvement should not be taken for granted. Targeted educational efforts are needed to ensure nurses' involvement in the prevention of human papillomavirus-related diseases.
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.
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.
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.
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.
Cites: MMWR Recomm Rep. 1999 Oct 1;48(RR-12):1-3710543657
Cites: Am J Trop Med Hyg. 1999 Nov;61(5):825-910586919
Few data are available concerning the long term immunogenicity of the pediatric doses of hepatitis B vaccines given to preteenagers. The long term effect of the booster dose in teenagers is unknown. We evaluated the immunogenicity of 2 pediatric hepatitis vaccines after primary vaccination and after a booster dose.
A prospective 15-year follow-up study of the immunogenicity of 2 hepatitis B vaccines was initiated in 1995 in Quebec City, Canada. One year apart, 1129 children 8-10 years old received Engerix-B 10 microg (EB), and 1126 received Recombivax-HB 2.5 microg (RB) vaccine after a 0-, 1-, 6-month schedule. After 5 years, one-third of the 2 cohorts were randomly selected. A booster dose of EB 10 microg or RB 5 microg was administered according to the vaccine used in the primary immunization. Antibodies were measured before, 1 month after and 1 year after the booster injection.
Before the booster dose, anti-HB surface antibody (HBs) was detected in 94.7% of the EB subjects and in 95.2% of the RB subjects (P = 0.85). The geometric mean titer (GMT) was higher in the EB than in the RB group (252 mIU/mL versus 66 mIU/mL, P or =10 mIU/mL. The anti-HBs GMT was 113,201 mIU/mL in the EB and 16,623 mIU/mL in the RB groups (P or =10 mIU/mL. The anti-HBs GMT was 14,028 mIU/mL in the EB and 3437 mIU/mL in the RB group (P
Hepatitis A vaccines have been available for more than a decade. Because the burden of hepatitis A virus has fallen in developed countries, the appropriate role of vaccination programmes, especially universal vaccination strategies, remains unclear. Cost-effectiveness analysis is a useful method of relating the costs of vaccination to its benefits, and may inform policy. This article systematically reviews the evidence on the cost effectiveness of hepatitis A vaccination in varying populations, and explores the effects of methodological quality and key modelling issues on the cost-effectiveness ratios.Cost-effectiveness/cost-utility studies of hepatitis A vaccine were identified via a series of literature searches (MEDLINE, EMBASE, HSTAR and SSCI). Citations and full-text articles were reviewed independently by two reviewers. Reference searching, author searches and expert consultation ensured literature saturation. Incremental cost-effectiveness ratios (ICERs) were abstracted for base-case analyses, converted to $US, year 2005 values, and categorised to reflect various levels of cost effectiveness. Quality of reporting, methodological issues and key modelling issues were assessed using frameworks published in the literature.Thirty-one cost-effectiveness studies (including 12 cost-utility analyses) were included from full-text article review (n = 58) and citation screening (n = 570). These studies evaluated universal mass vaccination (n = 14), targeted vaccination (n = 17) and vaccination of susceptibles (i.e. individuals initially screened for antibody and, if susceptible, vaccinated) [n = 13]. For universal vaccination, 50% of the ICERs were
Investigations conducted by public health in Quebec, Canada, following report of human exposure to a bat were reviewed to evaluate the implementation of the recommendation for rabies post-exposure prophylaxis (RPEP) for household bat exposure (without documented direct contact). Of all RPEP recommended, 12% was for direct bat contact with bite, 7% for direct bat contact without known bite and 81% for household exposure. When bat was not available for testing, RPEP was almost always recommended. Household bat exposure has become the most frequent reason for RPEP administration. Given the rarity of rabies, RPEP recommendations related to household bat exposure may warrant review.
After a mass-immunization campaign in the province of Quebec, Canada, from 1992 to 1993, a case-control study was conducted to evaluate the effectiveness of the polysaccharide vaccine, while controlling for the potential confounding effects of selected risk factors for serogroup C meningococcal disease.
The case patient group comprised 74 individuals with confirmed serogroup C meningococcal disease reported after the beginning of the campaign until 31 March 1998. Four control subjects, matched for age and place of residence, were randomly selected from the Quebec health insurance registry. Information on case patients was obtained from regional public health departments. Case patients and control subjects (or a family member) were interviewed by telephone. The analyses were conducted by using conditional logistic regression models.
Although the 95% confidence intervals (CIs) were large as a result of the small sample sizes, a high level of protection was found among children aged >or=6 years, during the first 2 years after vaccination (vaccine effectiveness, 95%; 95% CI, 68%-99%; P