Low prevalence of vaccine-type HPV infections in young women following the implementation of a school-based and catch-up vaccination in Quebec, Canada.

BACKGROUND: In Quebec, Canada, a school-based HPV vaccination for girls has been offered since 2008. The vaccine used in the program targets HPV16/18, responsible for ∼70% of cervical cancers and HPV6/11, responsible for the majority of anogenital warts. The objective of this study was to assess the prevalence of HPV in vaccinated and unvaccinated women. METHODS: Women aged 17-29 years were eligible to participate. Participants' age, vaccination status and diverse risk factors were assessed by a computer-assisted questionnaire. Biological specimens were obtained by self-sampling. HPV genotyping was performed by Linear Array. RESULTS: A total of 2,118 women were recruited. 2,042 completed the questionnaire and 1,937 provided a vaginal sample. Vaccination coverage varied from 83.5% in women aged 17-19 to 19.1% in those aged 23-29. The overall prevalence of HPV in sexually active women was 39.4% (95%CI: 37.0-41.7) and 56.7% of infected women had multiple type infections. The prevalence of vaccine HPV types varied by age and vaccination status except for women aged 23-29 for whom similar results were observed. Vaccine HPV types were detected in 0.3%, 1.4% and 10.5% of vaccinated women aged 17-19, 20-23, and 23-29 (p<0.05), respectively. HPV16 or HPV18 were detected in 10 women having received at least one dose of vaccine. Nine of these women were already sexually active at the time of vaccination. CONCLUSION: Infections with HPV types included in the vaccine are rare in women aged less than 23 years and are virtually absent in those who received at least one dose of vaccine before sexual debut.

Determinants of parents' decision to vaccinate their children against rotavirus: results of a longitudinal study.

Rotavirus disease is a common cause of health care utilization and almost all children are affected by the age of 5 years. In Canada, at the time of this survey (2008-09), immunization rates for rotavirus were <20%. We assessed the determinants of a parent's acceptance to have their child immunized against rotavirus. The survey instruments were based on the Theory of Planned Behavior. Data were collected in two phases. In all, 413 and 394 parents completed the first and second interviews, respectively (retention rate 95%). Most parents (67%) intended to immunize their child against rotavirus. Factors significantly associated with parental intentions (Phase 1) were as follows: perception of the moral correctness of having their child immunized (personal normative belief) and perception that significant others will approve of the immunization behavior (subjective norm), perceived capability of having their child immunized (perceived behavioral control) and household income. At Phase 2, 165 parents (42%) reported that their child was immunized against rotavirus. The main determinant of vaccination behavior was parental intention to have their child vaccinated, whereas personal normative beliefs influenced both intention and behavior. The acceptability of the rotavirus vaccine will be higher if health promotion addresses parental knowledge, attitudes and beliefs regarding the disease and the vaccine.

Clinicians' opinions on new vaccination programs implementation.

In Canada, several new vaccines were recently approved for clinical use or are expected to be soon. Decision-makers are faced with the choice whether or not to include these vaccines in publicly funded vaccination programs. The aim of this study was to assess Canadian pediatricians' and family physicians' opinions regarding 7 new vaccines, and perceived priority for the introduction of new programs. A self-administered, anonymous, mail-based questionnaire was sent during fall 2009 to a random sample of 1182 family physicians and to all 1852 Canadian pediatricians. Responses to 8 statements regarding frequency and severity of the diseases, efficacy and safety of the vaccines as well as feasibility of immunization programs were used to calculate priority scores to rank the 7 potential new vaccination programs (calculated scores ranging from 0 to 100). Overall response rate was 43%. The majority of respondents perceived the health and economic burden of diseases prevented by the seven new vaccines as important and considered new vaccines to be safe and effective. More than 90% of physicians strongly agreed or agreed that the new vaccines would be or are currently well accepted by the public and by the health professionals who administer vaccines, except for the HPV and rotavirus vaccines (respectively 30% and 29% strongly agreed or agreed). Mean priority scores were: 77.4 out of 100 for the measles, mumps, rubella and varicella (MMRV) combined vaccine; 75.6 for the hexavalent (DTaP-IPV-Hib-HBV) vaccine; 73.1 for the new pneumococcal conjugate vaccines; 69.8 for the meningococcal ACYW135; 68.9 for the combined hepatitis A and B; 63.5 for the human papillomavirus vaccine and 56.9 for the rotavirus vaccine. Health professionals' opinion is an important element to consider in the decision-making process regarding implementation of new immunization programs. Without health professional support, the introduction of a new vaccination program may be unsuccessful. In this study, the MMRV and the hexavalent (DTaP-IPV-Hib-HBV) vaccines received the highest ratings.

Cross-reactive antibody to swine influenza A(H3N2) subtype virus in children and adults before and after immunisation with 2010/11 trivalent inactivated influenza vaccine in Canada, August to November 2010.

In pre- and post-immunisation sera from children (17-120 months-old) and adults (20-59 years-old) immunised with 2010/11 trivalent inactivated influenza vaccine, we assessed age-related patterns of sero-susceptibility and vaccine-induced cross-reactive antibodies to a representative swine H3N2 (swH3N2) and a related ancestral human H3N2 (A/Sydney/5/1997) influenza virus. Few children but a greater proportion of adults showed pre-immunisation haemagglutination inhibition titres ≥40 to either virus. Titres increased with age among children but decreased in adults. Fewer than 20% showed a four-fold rise in antibody titres to either virus following immunisation. Further investigation is warranted to guide ongoing risk assessment and response to emerging swine H3N2 viruses.

Canadian paediatricians' opinions on rotavirus vaccination.

Rotavirus is the leading cause of dehydration and hospitalization due to gastroenteritis (GE) in young children. Almost all children are affected by the age of 5 years. Two safe and effective rotavirus vaccines are available for clinical use in Canada. In the context where rotavirus vaccination is recommended, but not publicly funded, we have assessed paediatricians' knowledge, attitudes and beliefs (KAB) regarding rotavirus disease and its prevention by vaccination. A self-administered anonymous questionnaire based upon the Health Belief Model and the Analytical framework for immunization programs was mailed to all 1852 Canadian paediatricians. The response rate was 50%. The majority of respondents rated consequences of rotavirus infection for young patients as moderate. Sixty-six percent considered that rotavirus disease occur frequently without vaccination and 62% estimated that the disease generates a significant economic burden. Sixty-nine percent of respondents considered rotavirus vaccines to be safe and 61%, to be effective. The reduction of severe GE cases was seen as the main benefit of rotavirus vaccination, while the risk of adverse events was the principal perceived barrier. Fifty-three percent (53%) indicated a strong intention to recommend rotavirus vaccines. In multivariate analysis, main determinant of paediatricians' intention to recommend rotavirus vaccines was the perceived health and economic burden of rotavirus diseases (partial R(2)=0.49, p<0.0001). More than half of surveyed paediatricians were willing to recommend rotavirus vaccines to their patients, but the proportion of respondents who had a strong intention to do so remains low when compared to several other new vaccines. As with other new vaccines, rotavirus vaccine uptake risks to remain low in Canada as long as it is not publicly funded.

Cost-utility of universal hepatitis A vaccination in Canada.

Hepatitis A (HA) vaccination in Canada is currently targeted toward high-risk groups. The cost-effectiveness and expected health outcomes of universal vaccination relative to targeted vaccination in low-incidence countries such as Canada are currently unknown. Here, we conducted a cost-utility analysis for this situation, with Canada as the study population. We included vaccine costs, time costs, infection costs, and public health costs. We assessed a range of possible universal vaccination strategies over an 80-year time horizon using multiple cost perspectives. A dynamic model was used to account for herd immunity. Aggregate health gains from switching to universal vaccination are modest (10-30 QALYs per year). However, a "9+9" strategy that replaces two doses of monovalent hepatitis B (HB) vaccine at 9/10 years (universally administered in most provinces) with two doses of bivalent HA/HB vaccine is cost-saving from the societal perspective. At a willingness to pay threshold of $50,000/QALY, mean net benefit is +49.4 QALYs (S.D. 12.6) from the societal perspective and +3.8 QALYS (S.D. 3.0) from the payer perspective for the "9+9" strategy. Net benefit from the payer perspective is sensitive to the marginal cost of HA/HB vaccine relative to HB vaccine. Similar conclusions may apply in other countries with low incidence and a targeted vaccination policy.

A dynamic model for assessing universal Hepatitis A vaccination in Canada.

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.