Coverage from Ontario, Canada's school-based HPV vaccine program: the first three years.

BACKGROUND: In 2007, Ontario implemented a school-based human papillomavirus (HPV) vaccination program targeting grade 8 girls. Girls may complete the series in grade 9 (extended eligibility). Limitations in the existing provincial data sources for assessing HPV vaccine coverage in Ontario prompted the use of two surveys of Health Units (HUs) to calculate provincial vaccine coverage for the first three years of the vaccination program. METHODS: We surveyed Ontario's 36 HUs in March and November 2011 to obtain vaccine coverage information, including source of denominator data, and use of local information systems. The second survey was necessary in order to assess coverage including extended eligibility for the third year. HU-reported HPV vaccine coverage was compared to coverage estimates obtained from two provincial systems: the Immunization Records Information System (IRIS) and the HPV reimbursement database, a system used to remunerate HUs for HPV vaccine doses administered. RESULTS: 100% of HUs participated in the two surveys. The provincial coverage estimates using HU-reported data were: 51% (2007-2008), 58% (2008-2009), and 59% (2009-2010) with large variation by HU. Coverage increased significantly over time. The number of HUs that were able to report on doses given as part of extended eligibility also increased over time (47% in 2007-2008 to 89% in 2009-2010; p=0.0008). Comparisons across the three data sources (survey, IRIS and reimbursement database) revealed significantly different coverage estimates. Class or school lists were the most common source of denominator data used by HUs (27/36, 75%), however independent schools were not included by all. CONCLUSIONS: As not all HUs were able to report on HPV vaccine coverage including extended eligibility doses these findings likely underestimate the true coverage attained by Ontario's program. Although coverage is below the Canadian Immunization Committee benchmark of 80% within two years of program implementation, the upward trend in coverage is encouraging.

Association between the 2008-09 seasonal influenza vaccine and pandemic H1N1 illness during Spring-Summer 2009: four observational studies from Canada.

BACKGROUND: In late spring 2009, concern was raised in Canada that prior vaccination with the 2008-09 trivalent inactivated influenza vaccine (TIV) was associated with increased risk of pandemic influenza A (H1N1) (pH1N1) illness. Several epidemiologic investigations were conducted through the summer to assess this putative association. STUDIES INCLUDED: (1) test-negative case-control design based on Canada's sentinel vaccine effectiveness monitoring system in British Columbia, Alberta, Ontario, and Quebec; (2) conventional case-control design using population controls in Quebec; (3) test-negative case-control design in Ontario; and (4) prospective household transmission (cohort) study in Quebec. Logistic regression was used to estimate odds ratios for TIV effect on community- or hospital-based laboratory-confirmed seasonal or pH1N1 influenza cases compared to controls with restriction, stratification, and adjustment for covariates including combinations of age, sex, comorbidity, timeliness of medical visit, prior physician visits, and/or health care worker (HCW) status. For the prospective study risk ratios were computed. Based on the sentinel study of 672 cases and 857 controls, 2008-09 TIV was associated with statistically significant protection against seasonal influenza (odds ratio 0.44, 95% CI 0.33-0.59). In contrast, estimates from the sentinel and three other observational studies, involving a total of 1,226 laboratory-confirmed pH1N1 cases and 1,505 controls, indicated that prior receipt of 2008-09 TIV was associated with increased risk of medically attended pH1N1 illness during the spring-summer 2009, with estimated risk or odds ratios ranging from 1.4 to 2.5. Risk of pH1N1 hospitalization was not further increased among vaccinated people when comparing hospitalized to community cases. CONCLUSIONS: Prior receipt of 2008-09 TIV was associated with increased risk of medically attended pH1N1 illness during the spring-summer 2009 in Canada. The occurrence of bias (selection, information) or confounding cannot be ruled out. Further experimental and epidemiological assessment is warranted. Possible biological mechanisms and immunoepidemiologic implications are considered.