Impact of interventions to improve HPV vaccination acceptance and uptake in school-based programs: Findings of a pilot project in Quebec

CONTEXT

Vaccination coverage against human papillomavirus (HPV) in school-based programs in Quebec, Canada, is suboptimal despite more than a decade of introduction. Three interventions to improve HPV vaccine acceptability and coverage in school-based programs were developed, implemented as part of a multicomponent strategy and evaluated.

METHOD

Sixty-four (64) schools were recruited, of which 32 received the interventions (pilot schools), and 32 received usual vaccination activities (control schools). Two approaches were used to assess the impact of the interventions. Pre-post questionnaires were completed by parents in both pilot and control schools. Quantitative analyses of vaccination coverage using the Quebec immunization registry were conducted.

RESULTS

Participating parents (n = 989 in the pre-intervention survey and n = 772 in the post-intervention one) were generally aware of HPV and HPV vaccination. Most parents were confident about vaccination, had little or no hesitation and had decided to have their child vaccinated. Parents in the pilot schools were less concerned about vaccine safety than those in the control schools after the interventions. Parents in the pilot schools were also more likely to have decided to have their child vaccinated. A statistically significant difference of 7.4 % in HPV vaccine coverage between pilot and control schools was observed (82.9 % vs 75.5 %, p <0.0001).

CONCLUSION

Although school-based programs offer equitable access to vaccination and minimize access barriers, it remains crucial to identify effective interventions to improve vaccine uptake further and reach the WHO cervical cancer elimination goal. Our multicomponent strategy appears to have positively impacted HPV vaccine acceptability and coverage and could be adapted to other contexts where vaccination is delivered in school-based programs.

Effectiveness of BNT162b2 Vaccine Against Omicron-SARS-CoV-2 Subvariants in Children 5-11 Years of Age in Quebec, Canada, January 2022 to January 2023

BACKGROUND

In premarketing clinical trials conducted before Omicron emergence, BNT162b2 vaccine efficacy against COVID-19 was 90% in children. We conducted postmarketing evaluation of 1- and 2-dose vaccine effectiveness (VE) against Omicron BA.1, BA.2 and BA.4/5 subvariants in 5- to 11-year olds.

METHODS

We estimated VE against SARS-CoV-2 infection using a test-negative design. Specimens collected between January 9, 2022, and January 7, 2023, from children 5-11 years old in Quebec, Canada, and tested by nucleic acid amplification test were eligible. We estimated VE by time since last vaccine dose, interval between doses and by period of Omicron subvariant predominance.

RESULTS

A total of 48,826 NAATs were included in overall analysis. From 14-55 to 56-385 days postvaccination, 2-dose VE against symptomatic infection decreased from 68% (95% CI, 62-74) to 25% (95% CI, 11-36). Two-dose VE with restriction to specimens collected from acute care hospitals (emergency rooms or wards) did not decline but was stable at ~40%. VE against symptomatic infection remained comparable at any interval between doses but increased with longer interval among children tested in acute care settings, from 18% (95% CI, -17 to 44) with 21- to 55-day interval to 69% (95% CI, 43-86) with ≥84-day interval. Two-dose VE against symptomatic infection dropped from 70% (95% CI, 63-76) during BA.1, to 32% (95% CI, 13-47) with BA.2 and to nonprotective during BA.4/5 dominance.

CONCLUSIONS

In children 5-11 years of age, VE against symptomatic infection was stable at any interval between doses but decreased with time since the last dose and against more divergent omicron subvariants.

School-based vaccination program against HPV and Hepatitis B: A longitudinal analysis of vaccine coverage between 2015 and 2021 in Quebec

BACKGROUND

HPV vaccination prevents cancers, including 90% of cervical cancer. Since 2008, a school-based HPV vaccination program has been implemented in Quebec, but vaccine coverage is suboptimal. The COVID-19 pandemic disrupted school-based vaccination programs. This study aimed to assess variation in HPV vaccination coverage in the school-based program between 2015 and 2022 in Quebec and to identify sociodemographic characteristics associated with non-vaccination.

METHODS

HPV vaccine coverage data were extracted from the Quebec Immunization Registry for students in Grade 4 and matched to the 2016 Canadian census sociodemographic data. Descriptive analysis was conducted to explore individual-level vaccine coverage according to sociodemographic data. A Generalized Estimating Equations model assessed the independent association between non-vaccination and students' sociodemographic characteristics.

RESULTS

HPV vaccine coverage (at least one dose) was 84% in 2018-2019 and 85% in 2019-2020. A decrease was observed during the pandemic. In 2020-2021, the HPV vaccine coverage (at least one dose) was 52% (at the end of the school year) and rose to 84% with intense catch-up activities. In 2021-2022, the coverage was slightly lower than before the pandemic (81%). Factors in the dissemination area were statistically significantly associated with non-vaccination: material (p-value = 0.0001) and social deprivation index (p-value = 0.0048), the proportion of immigration (p-value < 0.0001), and the language spoken at home (English (p-value = 0.0318), other than French or English (p-value = 0.0001).

CONCLUSION

School-based vaccination programs offer equitable access to vaccination, and our analysis showed that some groups have consistently lower vaccine acceptance and uptake. Strategies to improve HPV vaccine coverage should target children living in areas with a higher proportion of immigrants, non-French speakers, and people from underprivileged backgrounds. Although it is too early to assess the full impact of COVID-19 on school-based programs in Quebec, it remains important to ensure that catch-up strategies are implemented for missed doses.

"The problem is not lack of information": A qualitative study of parents and school nurses' perceptions of barriers and potential solutions for HPV vaccination in schools

BACKGROUND

HPV vaccination has been offered in school programs for over a decade in Quebec, Canada, but the vaccine coverages are not reaching the target coverage in several regions. This qualitative study aimed to describe barriers and enabling conditions of HPV vaccination as perceived by parents and school nurses and identify potential solutions to improve HPV vaccine uptake rates and acceptance in school-based programs.

METHODS

Three focus group discussions were conducted with parents of children in Grades 2 or 3 who were unsure or unwilling to vaccinate. Individual interviews were conducted with 24 school nurses. A thematic content analysis was performed using N'Vivo.

RESULTS

The main parental questions and concerns regarding the HPV vaccination were the children's young age, the possible side effects, the rationale behind boys' vaccination and the possible interaction with COVID-19 vaccination. Except for interaction with COVID-19 vaccination, these concerns remain similar to those identified before the pandemic. Interviews highlighted that the information on HPV vaccination provided by the public was not well understood by parents. Parents suggested different tools to access information tailored to their concerns and situation. From the nurses' perspective, HPV vaccination promotion tools such as decision-aids and social media communication campaigns were needed and could reduce their work.

CONCLUSION

COVID-19 may have disrupted the acceptance of the vaccines. While strategies to catch up on missed doses and reduce access barriers to vaccines are urgently needed, our findings highlight that a shift in attitudes toward routine vaccines may pose further challenges even if HPV vaccine coverage appears to have returned to pre-pandemic levels.

Effectiveness of previous infection-induced and vaccine-induced protection against hospitalisation due to omicron BA subvariants in older adults: a test-negative, case-control study in Quebec, Canada

BACKGROUND

Older adults (aged ≥60 years) were prioritised for COVID-19 booster vaccination due to severe outcome risk, but the risk for this group is also affected by previous SARS-CoV-2 infection and vaccination. We estimated vaccine effectiveness against omicron-associated hospitalisation in older adults by previously documented infection, time since last immunological event, and age group.

METHODS

This was a population-based test-negative case-control study done in Quebec, Canada, during BA.1 dominant (December, 2021, to March, 2022), BA.2 dominant (April to June, 2022), and BA.4/5 dominant (July to November, 2022) periods using provincial laboratory, immunisation, hospitalisation, and chronic disease surveillance databases. We included older adults (aged ≥60 years) with symptoms associated with COVID-19 who were tested for SARS-CoV-2 in acute-care hospitals. Cases were defined as patients who were hospitalised for COVID-19 within 14 days after testing positive; controls were patients who tested negative. Analyses spanned 3-14 months after last vaccine dose or previous infection. Logistic regression models compared COVID-19 hospitalisation risk by mRNA vaccine dose and previous infection versus unvaccinated and infection-naive participants.

FINDINGS

Between Dec 26, 2021, and Nov 5, 2022, we included 174 819 specimens (82 870 [47·4%] from men and 91 949 [52·6%] from women; from 8455 cases and 166 364 controls), taken from 2951 cases and 48 724 controls in the BA.1 period; 1897 cases and 41 702 controls in the BA.2 period; and 3607 cases and 75 938 controls in the BA.4/5 period. In participants who were infection naive, vaccine effectiveness against hospitalisation improved with dose number, consistent with a shorter median time since last dose, but decreased with more recent omicron subvariants. Four-dose vaccine effectiveness was 96% (95% CI 93-98) during the BA.1 period, 84% (81-87) during the BA.2 period, and 68% (63-72) during the BA.4/5 period. Regardless of dose number (two to five doses) or timing since previous infection, hybrid protection was more than 90%, persisted for at least 6-8 months, and did not decline with age.

INTERPRETATION

Older adults with both previous SARS-CoV-2 infection and two or more vaccine doses appear to be well protected for a prolonged period against hospitalisation due to omicron subvariants, including BA.4/5. Ensuring that older adults who are infection naive remain up to date with vaccination might reduce COVID-19 hospitalisations most efficiently.

FUNDING

Ministère de la Santé et des Services Sociaux du Québec.

TRANSLATION

For the French translation of the abstract see Supplementary Materials section.

Vaccine Effectiveness Against 12-Month Incident and Persistent Anal Human Papillomavirus Infection Among Gay, Bisexual, and Other Men Who Have Sex With Men

BACKGROUND

Real-world evidence of human papillomavirus (HPV) vaccine effectiveness (VE) against longitudinal outcomes is lacking among gay, bisexual, and other men who have sex with men (GBM). We compared 12-month incidence and persistence of anal HPV infection between vaccinated and unvaccinated GBM.

METHODS

We recruited GBM aged 16-30 years in Montreal, Toronto, and Vancouver, Canada, from 2017 to 2019. Participants were followed over a median of 12 months (interquartile range, 12-13 months). Participants self-reported HPV vaccination and self-collected anal specimens for HPV DNA testing. We calculated prevalence ratios (PR) for 12-month cumulative incidence and persistence with ≥1 quadrivalent vaccine type (HPV 6/11/16/18) between vaccinated (≥1 dose at baseline) and unvaccinated participants using a propensity score-weighted, modified Poisson regression.

RESULTS

Among 248 participants, 109 (44.0%) were vaccinated at baseline, of whom 62.6% received 3 doses. PRs for HPV 6/11/16/18 were 0.56 (95% confidence interval [CI], .24-1.31) for cumulative incidence and 0.53 (95% CI, .25-1.14) for persistence. PRs were 0.23 (95% CI, .05-1.03) and 0.08 (95% CI, .01-.59) for incidence and persistence, respectively, among participants who received their first dose at age ≤23 years and 0.15 (95% CI, .03-.68) and 0.12 (95% CI, .03-.54) among participants who were sexually active for ≤5 years before vaccination.

CONCLUSIONS

Findings support national recommendations for HPV vaccination at younger ages or soon after sexual debut.

Self-reported Human Papillomavirus Vaccination and Vaccine Effectiveness Among Men Who Have Sex with Men: A Quantitative Bias Analysis

BACKGROUND

Self-report of human papillomavirus (HPV) vaccination has ~80-90% sensitivity and ~75-85% specificity. We measured the effect of nondifferential exposure misclassification associated with self-reported vaccination on vaccine effectiveness (VE) estimates.

METHODS

Between 2017-2019, we recruited sexually active gay, bisexual, and other men who have sex with men aged 16-30 years in Canada. VE was derived as 1-prevalence ratio × 100% for prevalent anal HPV infection comparing vaccinated (≥1 dose) to unvaccinated men using a multivariable modified Poisson regression. We conducted a multidimensional and probabilistic quantitative bias analysis to correct VE estimates.

RESULTS

Bias-corrected VE estimates were relatively stable across sensitivity values but differed from the uncorrected estimate at lower values of specificity. The median adjusted VE was 27% (2.5-97.5th simulation interval = -5-49%) in the uncorrected analysis, increasing to 39% (2.5-97.5th simulation interval = 2-65%) in the bias-corrected analysis.

CONCLUSION

A large proportion of participants erroneously reporting HPV vaccination would be required to meaningfully change VE estimates.

BNT162b2 effectiveness against Delta and Omicron variants of SARS-CoV-2 in adolescents aged 12-17 years, by dosing interval and duration

BACKGROUND

Two- and three-dose BNT162b2 vaccine effectiveness (VE) against SARS-CoV-2 infection, including Delta and Omicron variants, was assessed among adolescents in Canada where first and second doses were spaced longer than the manufacturer-specified 3-week interval.

METHODS

Test-negative design estimated VE against laboratory-confirmed SARS-CoV-2 infection ≥14 days post-vaccination among 12-17-year-olds in Quebec and British Columbia, Canada between September 5, 2021-April 30, 2022 (epi-week 36-17). Delta-dominant and Omicron-dominant periods spanned epi-weeks 36-47 and 51-17, respectively. VE was explored by interval between first and second doses, time since second dose, and with a third dose.

RESULTS

VE against Delta was ≥90% to at least 5 months post-second dose. VE against Omicron decreased from ∼65-75% at 2-3 weeks to ≤50% by the 3rd month post-vaccination, restored to ∼65% by a third dose. Although confidence intervals overlapped, VE against Omicron was ∼5-7% higher (absolute) when first and second doses were spaced ≥8 vs. 3-4 weeks apart.

CONCLUSIONS

In adolescents, two BNT162b2 doses provided strong and sustained protection against Delta but reduced and rapidly-waning VE against Omicron. Longer interval between first and second doses and a third dose marginally improved Omicron protection. Updated vaccine antigens, increased doses and/or dosing-intervals may improve adolescent VE against immunological-escape variants.

Protection against omicron (B.1.1.529) BA.2 reinfection conferred by primary omicron BA.1 or pre-omicron SARS-CoV-2 infection among health-care workers with and without mRNA vaccination: a test-negative case-control study

BACKGROUND

There is a paucity of data on vaccine-induced or infection-induced (hybrid or natural) immunity against omicron (B.1.1.529) subvariant BA.2, particularly in comparing the effects of previous SARS-CoV-2 infection with the same or different genetic lineage. We aimed to estimate the protection against omicron BA.2 associated with previous primary infection with omicron BA.1 or pre-omicron SARS-CoV-2, among health-care workers with and without mRNA vaccination.

METHODS

We conducted a test-negative case-control study among health-care workers aged 18 years or older who were tested for SARS-CoV-2 in Quebec, Canada, between March 27 and June 4, 2022, when BA.2 was the predominant variant and was presumptively diagnosed with a positive test result. We identified cases (positive test during study period) and controls (negative test during study period) using the provincial laboratory database that records all nucleic acid amplification testing for SARS-CoV-2 in Quebec, and used the provincial immunisation registry to determine vaccination status. Logistic regression models compared the likelihood of BA.2 infection or reinfection (second positive test ≥30 days after primary infection) among health-care workers who had previous primary infection and none to three mRNA vaccine doses versus unvaccinated health-care workers with no primary infection.

FINDINGS

258 007 SARS-CoV-2 tests were done during the study period. Among those with a valid result and that met the inclusion criteria, there were 37 732 presumed BA.2 cases (2521 [6·7%] reinfections following pre-omicron primary infection and 659 [1·7%] reinfections following BA.1 primary infection) and 73 507 controls (7360 [10·0%] had pre-omicron primary infection and 12 315 [16·8%] had BA.1 primary infection). Pre-omicron primary infection was associated with a 38% (95% CI 19-53) reduction in BA.2 infection risk, with higher BA.2 protection among those who had also received one (56%, 95% CI 47-63), two (69%, 64-73), or three (70%, 66-74) mRNA vaccine doses. Omicron BA.1 primary infection was associated with greater protection against BA.2 infection (risk reduction of 72%, 95% CI 65-78), and protection was increased further among those who had received two doses of mRNA vaccine (96%, 95-96), but was not improved with a third dose (96%, 95-97).

INTERPRETATION

Health-care workers who had received two doses of mRNA vaccine and had previous BA.1 infection were subsequently well protected for a prolonged period against BA.2 reinfection, with a third vaccine dose conferring no improvement to that hybrid protection. If this protection also pertains to future variants, there might be limited benefit from additional vaccine doses for people with hybrid immunity, depending on timing and variant.

FUNDING

Ministère de la Santé et des Services Sociaux du Québec.

Estimated Protection of Prior SARS-CoV-2 Infection Against Reinfection With the Omicron Variant Among Messenger RNA-Vaccinated and Nonvaccinated Individuals in Quebec, Canada

IMPORTANCE

The Omicron variant is phylogenetically and antigenically distinct from earlier SARS-CoV-2 variants and the original vaccine strain. Protection conferred by prior SARS-CoV-2 infection against Omicron reinfection, with and without vaccination, requires quantification.

OBJECTIVE

To estimate the protection against Omicron reinfection and hospitalization conferred by prior heterologous non-Omicron SARS-CoV-2 infection and/or up to 3 doses of an ancestral, Wuhan-like messenger RNA (mRNA) vaccine.

DESIGN, SETTING, AND PARTICIPANTS

This test-negative, population-based case-control study was conducted between December 26, 2021, and March 12, 2022, and included community-dwelling individuals aged 12 years or older who were tested for SARS-CoV-2 infection in the province of Quebec, Canada.

EXPOSURES

Prior laboratory-confirmed SARS-CoV-2 infection with or without mRNA vaccination.

MAIN OUTCOMES AND MEASURES

The main outcome was laboratory-confirmed SARS-CoV-2 reinfection and associated hospitalization, presumed to be associated with the Omicron variant according to genomic surveillance. The odds of prior infection with or without vaccination were compared for case participants with Omicron infection and associated hospitalizations vs test-negative control participants. Estimated protection was derived as 1 - the odds ratio, adjusted for age, sex, testing indication, and epidemiologic week. Analyses were stratified by severity and time since last non-Omicron infection or vaccine dose.

RESULTS

This study included 696 439 individuals (224 007 case participants and 472 432 control participants); 62.2% and 63.9% were female and 87.4% and 75.5% were aged 18 to 69 years, respectively. Prior non-Omicron SARS-CoV-2 infection was detected for 9505 case participants (4.2%) and 29 712 control participants (6.3%). Among nonvaccinated individuals, prior non-Omicron infection was associated with a 44% reduction (95% CI, 38%-48%) in Omicron reinfection risk, which decreased from 66% (95% CI, 57%-73%) at 3 to 5 months to 35% (95% CI, 21%-47%) at 9 to 11 months postinfection and was below 30% thereafter. The more severe the prior infection, the greater the risk reduction. Estimated protection (95% CI) against Omicron infection was consistently significantly higher among vaccinated individuals with prior infection compared with vaccinated infection-naive individuals, with 65% (63%-67%) vs 20% (16%-24%) for 1 dose, 68% (67%-70%) vs 42% (41%-44%) for 2 doses, and 83% (81%-84%) vs 73% (72%-73%) for 3 doses. For individuals with prior infection, estimated protection (95% CI) against Omicron-associated hospitalization was 81% (66%-89%) and increased to 86% (77%-99%) with 1, 94% (91%-96%) with 2, and 97% (94%-99%) with 3 mRNA vaccine doses, without signs of waning.

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that vaccination with 2 or 3 mRNA vaccine doses among individuals with prior heterologous SARS-CoV-2 infection provided the greatest protection against Omicron-associated hospitalization. In the context of program goals to prevent severe outcomes and preserve health care system capacity, a third mRNA vaccine dose may add limited protection in twice-vaccinated individuals with prior SARS-CoV-2 infection.

Single-Dose Messenger RNA Vaccine Effectiveness Against Severe Acute Respiratory Syndrome Coronavirus 2 in Healthcare Workers Extending 16 Weeks Postvaccination: A Test-Negative Design From Québec, Canada

BACKGROUND

In Canada, first and second doses of messenger RNA (mRNA) vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were uniquely spaced 16 weeks apart. We estimated 1- and 2-dose mRNA vaccine effectiveness (VE) among healthcare workers (HCWs) in Québec, Canada, including protection against varying outcome severity, variants of concern (VOCs), and the stability of single-dose protection up to 16 weeks postvaccination.

METHODS

A test-negative design compared vaccination among SARS-CoV-2 test-positive and weekly matched (10:1), randomly sampled, test-negative HCWs using linked surveillance and immunization databases. Vaccine status was defined by 1 dose ≥14 days or 2 doses ≥7 days before illness onset or specimen collection. Adjusted VE was estimated by conditional logistic regression.

RESULTS

Primary analysis included 5316 cases and 53 160 controls. Single-dose VE was 70% (95% confidence interval [CI], 68%-73%) against SARS-CoV-2 infection; 73% (95% CI, 71%-75%) against illness; and 97% (95% CI, 92%-99%) against hospitalization. Two-dose VE was 86% (95% CI, 81%-90%) and 93% (95% CI, 89%-95%), respectively, with no hospitalizations. VE was higher for non-VOCs than VOCs (73% Alpha) among single-dose recipients but not 2-dose recipients. Across 16 weeks, no decline in single-dose VE was observed, with appropriate stratification based upon prioritized vaccination determined by higher vs lower likelihood of direct patient contact.

CONCLUSIONS

One mRNA vaccine dose provided substantial and sustained protection to HCWs extending at least 4 months postvaccination. In circumstances of vaccine shortage, delaying the second dose may be a pertinent public health strategy.

Time trends in social contacts of individuals according to comorbidity and vaccination status, before and during the COVID-19 pandemic

BACKGROUND

As we are confronted with more transmissible/severe variants with immune escape and the waning of vaccine efficacy, it is particularly relevant to understand how the social contacts of individuals at greater risk of COVID-19 complications evolved over time. We described time trends in social contacts of individuals according to comorbidity and vaccination status before and during the first three waves of the COVID-19 pandemic in Quebec, Canada.

METHODS

We used data from CONNECT, a repeated cross-sectional population-based survey of social contacts conducted before (2018/2019) and during the pandemic (April 2020 to July 2021). We recruited non-institutionalized adults from Quebec, Canada, by random digit dialling. We used a self-administered web-based questionnaire to measure the number of social contacts of participants (two-way conversation at a distance ≤2 m or a physical contact, irrespective of masking). We compared the mean number of contacts/day according to the comorbidity status of participants (pre-existing medical conditions with symptoms/medication in the past 12 months) and 1-dose vaccination status during the third wave. All analyses were performed using weighted generalized linear models with a Poisson distribution and robust variance.

RESULTS

A total of 1441 and 5185 participants with and without comorbidities, respectively, were included in the analyses. Contacts significantly decreased from a mean of 6.1 (95%CI 4.9-7.3) before the pandemic to 3.2 (95%CI 2.5-3.9) during the first wave among individuals with comorbidities and from 8.1 (95%CI 7.3-9.0) to 2.7 (95%CI 2.2-3.2) among individuals without comorbidities. Individuals with comorbidities maintained fewer contacts than those without comorbidities in the second wave, with a significant difference before the Christmas 2020/2021 holidays (2.9 (95%CI 2.5-3.2) vs 3.9 (95%CI 3.5-4.3); P<0.001). During the third wave, contacts were similar for individuals with (4.1, 95%CI 3.4-4.7) and without comorbidities (4.5, 95%CI 4.1-4.9; P=0.27). This could be partly explained by individuals with comorbidities vaccinated with their first dose who increased their contacts to the level of those without comorbidities.

CONCLUSIONS

It will be important to closely monitor COVID-19-related outcomes and social contacts by comorbidity and vaccination status to inform targeted or population-based interventions (e.g., booster doses of the vaccine).

Time trends in social contacts before and during the COVID-19 pandemic: the CONNECT study

BACKGROUND

Since the beginning of the COVID-19 pandemic, many countries, including Canada, have adopted unprecedented physical distancing measures such as closure of schools and non-essential businesses, and restrictions on gatherings and household visits. We described time trends in social contacts for the pre-pandemic and pandemic periods in Quebec, Canada.

METHODS

CONNECT is a population-based study of social contacts conducted shortly before (2018/2019) and during the COVID-19 pandemic (April 2020 - February 2021), using the same methodology for both periods. We recruited participants by random digit dialing and collected data by self-administered web-based questionnaires. Questionnaires documented socio-demographic characteristics and social contacts for two assigned days. A contact was defined as a two-way conversation at a distance ≤ 2 m or as a physical contact, irrespective of masking. We used weighted generalized linear models with a Poisson distribution and robust variance (taking possible overdispersion into account) to compare the mean number of social contacts over time and by socio-demographic characteristics.

RESULTS

A total of 1291 and 5516 Quebecers completed the study before and during the pandemic, respectively. Contacts significantly decreased from a mean of 8 contacts/day prior to the pandemic to 3 contacts/day during the spring 2020 lockdown. Contacts remained lower than the pre-COVID period thereafter (lowest = 3 contacts/day during the Christmas 2020/2021 holidays, highest = 5 in September 2020). Contacts at work, during leisure activities/in other locations, and at home with visitors showed the greatest decreases since the beginning of the pandemic. All sociodemographic subgroups showed significant decreases of contacts since the beginning of the pandemic. The mixing matrices illustrated the impact of public health measures (e.g. school closure, gathering restrictions) with fewer contacts between children/teenagers and fewer contacts outside of the three main diagonals of contacts between same-age partners/siblings and between children and their parents.

CONCLUSION

Physical distancing measures in Quebec significantly decreased social contacts, which most likely mitigated the spread of COVID-19.

Two-Dose Severe Acute Respiratory Syndrome Coronavirus 2 Vaccine Effectiveness With Mixed Schedules and Extended Dosing Intervals: Test-Negative Design Studies From British Columbia and Quebec, Canada

BACKGROUND

The Canadian coronavirus disease 2019 (COVID-19) immunization strategy deferred second doses and allowed mixed schedules. We compared 2-dose vaccine effectiveness (VE) by vaccine type (mRNA and/or ChAdOx1), interval between doses, and time since second dose in 2 of Canada's larger provinces.

METHODS

Two-dose VE against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection or hospitalization among adults ≥18 years, including due to Alpha, Gamma, and Delta variants of concern (VOCs), was assessed ≥14 days postvaccination by test-negative design studies separately conducted in British Columbia and Quebec, Canada, between 30 May and 27 November (epi-weeks 22-47) 2021.

RESULTS

In both provinces, all homologous or heterologous mRNA and/or ChAdOx1 2-dose schedules were associated with ≥90% reduction in SARS-CoV-2 hospitalization risk for ≥7 months. With slight decline from a peak of >90%, VE against infection was ≥80% for ≥6 months following homologous mRNA vaccination, lower by ∼10% when both doses were ChAdOx1 but comparably high following heterologous ChAdOx1 + mRNA receipt. Findings were similar by age group, sex, and VOC. VE was significantly higher with longer 7-8-week versus manufacturer-specified 3-4-week intervals between mRNA doses.

CONCLUSIONS

Two doses of any mRNA and/or ChAdOx1 combination gave substantial and sustained protection against SARS-CoV-2 hospitalization, spanning Delta-dominant circulation. ChAdOx1 VE against infection was improved by heterologous mRNA series completion. A 7-8-week interval between first and second doses improved mRNA VE and may be the optimal schedule outside periods of intense epidemic surge. Findings support interchangeability and extended intervals between SARS-CoV-2 vaccine doses, with potential global implications for low-coverage areas and, going forward, for children.

Human papillomavirus (HPV) vaccination across a cascade of knowledge, willingness, and uptake among gay, bisexual, and other men who have sex with men in Canada's three largest cities

BACKGROUND

Some Canadian jurisdictions offer publicly funded HPV vaccine to gay, bisexual, and other men who have sex with men (GBM) aged ≤26 years. We characterized factors associated with being in different stages of HPV vaccination.

METHODS

Engage is a sexual health study of GBM in the three largest Canadian cities recruited via respondent driven sampling (RDS). We categorized participants as: (1) unaware of HPV vaccine, (2) undecided/unwilling to get vaccinated, (3) willing to get vaccinated, (4) vaccinated with one or more doses. Our RDS-II weighted analyses used multinomial logistic regression to identify factors associated with being in earlier stages of the cascade compared to Stage 4.

RESULTS

Across the cities, 26-40%, 7-14%, 33-39%, and 13-28% were in Stages 1 to 4, respectively. Compared to Stage 4, being in earlier stages of the cascade was associated with bisexual-identification (Stage 1: adjusted odds ratio[aOR] = 2.84, 95% confidence interval[CI] = 1.06-7.62; Stage 2: aOR = 3.09, 95%CI = 1.19-8.05), having immigrated to Canada (Stage 1: aOR = 1.79, 95%CI 1.07-2.99), preference to keep same-sex romantic relationships private (Stage 1: aOR = 1.25, 95% CI = 1.05-1.48; Stage 2: aOR = 1.24, 95%CI = 1.05-1.46), not receiving sexual health information (Stage 1: aOR = 0.31, 95% CI = 0.13-0.71; Stage 2: aOR = 0.27, 95%CI = 0.12-0.64), not accessing a health-care provider (Stage 2: aOR = 0.36, 95%CI = 0.15-0.83), and no past hepatitis A/B vaccination (Stage 1: aOR = 0.16, 95% CI = 0.09-0.30; Stage 2: aOR = 0.18, 95%CI = 0.09-0.35; Stage 3: aOR = 0.38, 95%CI = 0.21-0.61).

DISCUSSION

Interventions are needed to reduce social and financial barriers, increase sexual health knowledge, and improve GBM-competent health-care access to increase vaccine uptake among GBM.

Sexual behavior, clinical outcomes and attendance of cervical cancer screening by HPV vaccinated and unvaccinated sexually active women

Concerns were raised about HPV vaccination possibly leading to riskier sexual behavior. We assessed sexual behaviors, risk of sexually transmitted infection, and attendance to cervical cancer screening by HPV vaccinated and unvaccinated young women. In this analysis, 1475 questionnaires completed by women aged 17-29 years were included. The majority of respondents (67.9%) were vaccinated against HPV. The proportion of those vaccinated decreased with age: from 93.2% in those aged 17-19 to 72.9% in those aged 20-22, and 21.8% in 23-29-year olds. A higher proportion of unvaccinated respondents had at least one sexual intercourse under the age of 15 when compared to those vaccinated (30% vs. 23%, p < .0001). The number of sexual partners during the last 12 months was similar between vaccinated and unvaccinated participants. Vaccinated participants reported more condom use (45% versus 38%; p = .0002), and less sexually transmitted infections (10% versus 28%; p < .0001), and less anogenital condylomas (2.2% vs. 11.6%; p < .0001). A screening test has been reported by 51% and 77% of vaccinated and unvaccinated participants, respectively (p < .0001). The association between vaccination status and cervical cancer screening disappeared when adjusting for participants' age. The study results consolidate the existing body of data regarding the absence of an impact of HPV vaccination on sexual behavior or use of contraceptives.

Human papillomavirus (HPV) vaccine uptake among a community-recruited sample of gay, bisexual, and other men who have sex with men in the three largest cities in Canada from 2017 to 2019

INTRODUCTION

In 2015/2016, Canada's largest provinces implemented publicly-funded human papillomavirus (HPV) vaccination programs for gay, bisexual, and other men who have sex with men (GBM) ≤ 26 years old. We sought to describe HPV vaccine uptake among GBM and determine barriers and facilitators to vaccine initiation with a focus on healthcare access and utilization.

METHODS

Engage is a cohort study among GBM aged 16 + years in three Canadian cities recruited from 2017 to 2019 via respondent driven sampling (RDS). Men completed a comprehensive questionnaire at baseline. By publicly-funded vaccine eligibility (≤26 years old = eligible for vaccination, ≥27 years old = ineligible), we described HPV vaccine uptake (initiation = 1 + dose, completion = 3 doses) and explored factors associated with vaccine initiation using Poisson regression. All analyses were weighted with the RDS-II Volz-Heckathorn estimator.

RESULTS

Across the three cities, 26-35% and 14-21% of men ≤ 26 years and 7-26% and 2-9% of men ≥ 27 years initiated and completed HPV vaccination, respectively. Vaccine initiation was significantly associated with STI/HIV testing or visiting a HIV care specialist in the past six months (≤26: prevalence ratio[PR] = 2.15, 95% confidence interval[CI] 1.06-4.36; ≥27: PR = 2.73, 95%CI 1.14-6.51) and past hepatitis A or B vaccination (≤26: PR = 2.88, 95%CI 1.64-5.05; ≥27: PR = 2.03, 95%CI 1.07-3.86). Among men ≥ 27 years old, vaccine initiation was also positively associated with accessing PrEP, living in Vancouver or Toronto, but negatively associated with identifying as Latin American and increasing age. Vaccine initiation was twice as likely among men ≥ 27 years with private insurance versus no insurance.

CONCLUSIONS

Sixty-five to 74% of men eligible for publicly-funded vaccine across the three cities remained unvaccinated against HPV by 2019. High vaccine cost may partly explain even lower uptake among men ≥ 27 years old. Men seeking sexual health care were more likely to initiate vaccination; bundling vaccination with these services may help improve HPV vaccine uptake.

Immunogenicity of 2 and 3 Doses of the Quadrivalent Human Papillomavirus Vaccine up to 120 Months Postvaccination: Follow-up of a Randomized Clinical Trial

Background

Several countries have implemented a 2-dose (2D) human papillomavirus (HPV) vaccination schedule for adolescents based on immunobridging studies. We compared immunogenicity of 2D vs 3-dose (3D) schedules of the quadrivalent vaccine (4vHPV) up to 10 years after the first dose.

Methods

Girls aged 9–13 years were randomized to receive 2D or 3D and were compared with women aged 16–26 receiving 3D at day 1 and months 7, 24, and 120 after the first dose. Antibody levels for HPV6/11/16/18 were evaluated using the competitive Luminex immunoassay (cLIA) and total immunoglobulin G assay. Geometric mean titers (GMTs) and seropositivity rates were compared between the different groups at different time points. Noninferiority of GMT ratios was defined as the lower bound of the 2-sided 95% confidence interval (CI) being greater than 0.5. Kinetics of antibody titers over time among study groups were examined.

Results

At 120 months, data from 35 2D girls, 38 3D girls, and 30 3D women were used for analyses. cLIA seropositivity rates were above 95% for all HPV vaccine types and all schedules, except HPV18, with the lowest seropositivity observed among 3D women (60.0%; 95% CI, 40.6%–77.3%). GMT ratios (cLIA) for both 2D and 3D girls were noninferior to 3 doses in women for HPV6/11/16/18. Trends were comparable between assays.

Conclusions

GMTs for HPV6/11/16/18 after 2D or 3D of 4vHPV in girls were noninferior to 3D in adult women up to 120 months postvaccination. This study demonstrates long-term immunogenicity of the 2D HPV vaccine schedule.

Participation in an action research project on vaccine services for children: relationship with vaccine delays

Multicomponent interventions are effective in improving vaccine coverage. However, few studies have assessed their effect on timely vaccination. The aim of this study was to compare the proportion of children with vaccine delays at 2- and 12-month visits according to whether or not health centers have participated in an action research project on the organization of vaccination services for 0-5-year-olds. The action research project included a multicomponent intervention and was conducted between 2011 and 2015 in Quebec, Canada. An ecological before/after design was used for this analysis. A total of 264,579 DTaP-IPV-Hib (2-month visits) and 240,541 Men-C-C (12-month visits) vaccine doses were administered during 2011-2012 to 2014-2015 fiscal years, including 19% in 14 participating health centers and the remaining in 78 nonparticipating centers. Vaccine delays demonstrated a more pronounced decreasing trend in participating versus nonparticipating health centers (p < .0001 at 2 and 12 months). Between 2011-2012 and 2014-2015, participating centers managed to eliminate 35% of their vaccine delays at 2-month visits and 33% at 12-month visits, whereas nonparticipating centers eliminated 19% of delays at both visits. Our results are consistent with a positive impact of the multicomponent intervention, despite the fact that it had not specifically aimed at decreasing vaccine delays.

A systematic literature review of the recombinant subunit herpes zoster vaccine use in immunocompromised 18-49 year old patients

BACKGROUND

The adjuvanted recombinant zoster vaccine (RZV) is indicated for prevention of herpes zoster (HZ) in adults aged ≥50 years. Questions regarding the use of RZV in immunocompromised patients < 50-year-old, who are at increased risk for HZ, were raised.

OBJECTIVES

The objective of this systematic review was to consolidate existing evidences on safety, immunogenicity and efficacy of RZV in immunocompromised adults aged 18-49 years.

METHODS

Four databases were searched. Preferred Reporting Items for Systematic review and Meta-Analysis Protocols (PRISMA-P) guidelines were followed. Screening and classification of search items was performed using the web-based platform DistillerSR.

RESULTS

The search identified 1389 potentially relevant records. Six studies fulfilled inclusion criteria. The proportion of patients aged 18-49 varied between 23 and 62%. Pain at injection site (98.6%) and fatigue (75.3%) were the most common adverse events. The proportion of patients reporting serious adverse events (SAEs) ranged between 8.1 and 30.8% in RZV and between 4.1 and 36.5% in placebo groups. SAEs deemed related to vaccination were reported in < 1% of patients in both RZV and placebo groups. The proportion of patients that experienced clinically significant underlying disease-related events ranged between 0.0 and 20.0% in RZV and 0.0 and 26.7% in placebo groups. The humoral and cell-mediated immune response rate ranged between 65.4 and 96.2% and 50.0-93.0%, respectively. Vaccine efficacy in hematopoietic stem cell transplant patients was 72% (95%CI, 39-88%) in 18-49-year-olds and 67% (95%CI, 53-78%) in ≥ 50-year-olds (median follow-up 21 months). Vaccine efficacy in ≥ 18-year-old patients with hematologic malignancies was estimated at 87.2% (95%CI, 44.3-98.6%) up to 13 months post-vaccination.

CONCLUSIONS

Results suggest that RZV has an acceptable safety profile and induces immunity in an important proportion of ≥ 18-year-old immunocompromised patients. Longer follow-up studies are warranted to assess the duration of RZV induced immunity in immunocompromised patients.

Effectiveness and cost-effectiveness of vaccination against herpes zoster in Canada: a modelling study

BACKGROUND

Two vaccines against herpes zoster are currently authorized for use in Canada: the recombinant subunit zoster vaccine and live attenuated zoster vaccine. We compared the effectiveness and cost-effectiveness of these 2 vaccines.

METHODS

We used a decision analytic static cohort model parametrized with Canadian epidemiologic and economic data. We performed the economic analysis from the health care system perspective, using a lifetime horizon and a 3% discount rate for costs and benefits. The primary outcome was the incremental cost per quality-adjusted life-year (QALY) gained, relative to no vaccination. We ran 30 000 simulations varying all model parameters, including vaccine costs, efficacy and waning.

RESULTS

The number needed to vaccinate (NNV) was higher for the live attenuated zoster vaccine than for the recombinant subunit zoster vaccine for all herpes zoster-related events at all ages. For example, in persons exactly 65 years old, for herpes zoster, median NNV was 21 (90% uncertainty interval [UI] 13-31) versus 8 (90% UI 6-18), and for postherpetic neuralgia, NNV was 64 (90% UI 33-93) versus 31 (90% UI 23-73). For the recombinant vaccine, the median cost-effectiveness ratios varied between cost-saving and $25 881 per QALY gained for adults aged 50 years or older. For the live vaccine, the cost-effectiveness ratios varied between cost-saving and $130 587 per QALY gained and were less than $45 000 per QALY gained only for those 65 to 75 years old. Given its higher efficacy, we estimated that the cost for the complete series of the recombinant vaccine could be $150 to $200 more than the cost of the live vaccine and still be considered cost-effective.

INTERPRETATION

Our model predicted that the recombinant subunit zoster vaccine is likely cost-effective in Canada for adults 60 years or older, and is likely more cost-effective than live attenuated zoster vaccine. These results have informed updated national and provincial recommendations on herpes zoster vaccination.

Children vaccination coverage surveys: Impact of multiple sources of information and multiple contact attempts

BACKGROUND

Monitoring vaccination coverage is an essential component of vaccination program evaluation. In Québec (Canada), children vaccination coverage surveys are conducted every two years since 2006. The objectives of this study were to evaluate the impact of supplementing data based on vaccination booklets with data from vaccine providers, on the final estimated vaccination coverage and to compare vaccination coverage between respondents to each survey contact attempt.

METHODS

Data from six cross-sectional surveys were used, which included 3508 children aged 2 years. Parents were invited to transcribe the information available in their child's vaccination booklet on the questionnaire received by mail. The survey included a maximum of 4 contact attempts to obtain a response. Data were completed among vaccine providers identified by parents. The main outcome was a complete vaccination status by 24 months of age.

RESULTS

The addition of data from vaccine providers to those present in vaccination booklets increased the proportion of children fully vaccinated from 5.5% to 23.7% depending on the survey year. The proportion of children fully vaccinated by 24 months of age estimated among respondents to contact 1 was only 2.1% higher than the estimates among all respondents.

CONCLUSIONS

Without validation among vaccine providers for children with missing doses according to vaccination booklets, results underestimated vaccination coverage in the target population. Conducting multiple contact attempts increased the response rate but had limited impact on the validity of estimates. It would be useful in future surveys to present the coverage obtain from respondents to each contact attempt.

Priming effect of bivalent and quadrivalent vaccine for HPV 31/33/45/52: an exploratory analysis from two clinical trials

The main objective of this post hoc analysis is to compare the magnitude of the immune response to HPV31/33/45/52 and 58 after a dose of 9vHPV vaccine given to naïve (previously unvaccinated) subjects and subjects previously vaccinated with a dose of 2vHPV or 4vHPV vaccine. Results from two clinical trials conducted in the same region, in comparable populations and by the same research team were included in this analysis. In study A, a dose of 9vHPV was administered 6 months after a single dose of 2vHPV as well as to naïve subjects. In study B, a dose of 9vHPV was administered 36-96 months (mean 65 months) after a single dose of 4vHPV. Blood samples were collected just before and one month post-9vHPV vaccine administration. For both studies, antibody responses were measured using the same 9-plex virus-like particle based IgG ELISA (M9ELISA). One month after 9vHPV dose administration, all subjects were seropositive to HPV 31/33/45/52 and 58. Subjects who had previously received 2vHPV or 4vHPV had significantly higher (1.8-8.0-fold) GMTs than naive subjects for HPV31/33/45/52 types but not for HPV58. GMTs to HPV31/33/45/52 and 58 were not significantly different between subjects who received a 2vHPV or 4vHPV dose prior to 9vHPV. The strong anamnestic response to one dose of 9vHPV given as late as 3-8 years after a single dose of 2vHPV or 4vHPV vaccine indicates these vaccines induced priming to types only included in the 9vHPV vaccine.

Promoting vaccination in maternity wards ─ motivational interview technique reduces hesitancy and enhances intention to vaccinate, results from a multicentre non-controlled pre- and post-intervention RCT-nested study, Quebec, March 2014 to February 2015

BackgroundMany countries are grappling with growing numbers of parents who delay or refuse recommended vaccinations for their children. This has created a need for strategies to address vaccine hesitancy (VH) and better support parental decision-making regarding vaccination.AimTo assess vaccination intention (VI) and VH among parents who received an individual motivational-interview (MI) based intervention on infant immunisation during post-partum stay at a maternity ward between March 2014 and February 2015.MethodsThis non-controlled pre-/post-intervention study was conducted using the results from parents enrolled in the intervention arm of the PromoVaQ randomised control trial (RCT), which was conducted in four maternity wards across the Province of Quebec. Participants (n = 1,223) completed pre- and post-intervention questionnaires on VI and VH using Opel's score. Pre-/post-intervention measures were compared using McNemar's test for categorical variables and Wilcoxon signed-rank test for continuous variables.ResultsPre-intervention: overall VI was 78% and significantly differed across maternity wards (74%, 77%, 84%, 79%, p = 0.02). Post-intervention: VI rose significantly across maternity wards (89%, 85%, 95%, 93%) and the overall increase in VI was 12% (78% vs 90%, p < 0.0001). VH corroborated these observations, pre- vs post-intervention, for each maternity ward (28% vs 16%, 29% vs 21%, 27% vs 17%, 24% vs 13%). Overall, VH was curbed post-intervention by 40% (27% vs 16%; p < 0.0001).ConclusionsCompared with pre-intervention status, participants who received the MI-based intervention on immunisation displayed lower hesitancy and greater intention to vaccinate their infant at 2 months of age.

Long intervals between two doses of HPV vaccines and magnitude of the immune response: a post hoc analysis of two clinical trials

The objective of this analysis was to compare the anti-HPV GMTs and their distribution after a 6-month or a 3-8 -y interval between two HPV vaccine doses. The results from two clinical trials, conducted by the same team in the same region, with serological assays performed at the same laboratory using the same ELISA methodology were compared. In the first study, 173 9-10-y-old girls and boys received two doses of 9vHPV vaccine at a 6-month interval; in the second study, 31 girls vaccinated with one dose of 4vHPV at the age of 9-14 y received a dose of 9vHPV 3-8 y later (mean 5.4 y). In both studies, blood samples were collected before and 1 month post second dose. Despite large differences in the time since the first dose, all subjects (100%) were seropositive to the common 4 HPV types (6, 11, 16 and 18) to both vaccines, with comparable GMTs and titer distributions before the second dose. One month post second dose, the GMTs increased 40-91-fold for those with a 6-month interval between doses and 60-82-fold for those with a 3-8-y interval. Titer distributions after the booster dose were comparable in the two studies. These results indicate that 2-dose HPV vaccination schedules with an interval of several years could be used for pre-adolescents. Intervals longer than 6 months may facilitate logistics for immunization programs and could be useful during periods of vaccine shortage or as a transition while the effectiveness of a one-dose schedule is being evaluated.

Challenges and opportunities of school-based HPV vaccination in Canada

Primary prevention of human papillomavirus (HPV) through vaccination is a high priority in Canada's cancer prevention efforts. All Canadian provinces and territories have introduced publicly funded, school-based vaccination programs against HPV, but vaccine uptake remains suboptimal in some jurisdictions. We conducted a descriptive qualitative study to better understand the determinants of low HPV vaccine uptake and identify strategies to enhance vaccine acceptance using the socio-ecological model. In Quebec, interviews and focus groups were held in 2015-2016 with 70 key informants including immunization managers, school nurses, school principals, teachers and parents of Grade 4 students (9 years of age). Our findings showed that HPV vaccine uptake was dependent on many interrelated factors at the individual and interpersonal level (e.g. knowledge and attitudes of the different players involved in the vaccination system), at the community level (e.g. social group values and norms, media coverage around the HPV vaccine), at the organizational level (e.g. allocated resources, information provision, consent process, immunization setting and environment) and at the policy level (e.g. changes in provincial HPV vaccine program). We are using the data collection and interpretation tools and approaches developed by our team and used in Quebec to expand our study to four other provinces (British Columbia, Alberta, Ontario and Nova Scotia). We are conducting environmental scans, semi-structured interviews and a survey to better understand the determinants of low HPV vaccine uptake and identify strategies to enhance vaccine acceptance. Having an in-depth understanding of the determinants of HPV vaccination in school settings is critical in order to identify root causes of the suboptimal vaccine uptake and to develop tailored interventions to address these on both supply- and demand-side issues.

Promoting vaccination in the province of Québec: the PromoVaQ randomized controlled trial protocol

Background

Vaccination has a huge public health impact. Maintaining vaccine coverage is key to avoid the devastating consequences of resurgence. In the Province of Québec, vaccine coverage in young children are sub-optimal, mostly due to ambivalence toward vaccine safety and efficacy. We previously conducted a regional study in the Québec’s Eastern Townships region, the PromoVac Study, to test a new educational intervention, based on motivational interviewing techniques, aimed at promoting infant vaccination. This first study evidenced that the intervention led to a marked increase in mothers’ intention to vaccinate, and vaccine coverage in their infants. The current study protocol aims at scaling up these results at a provincial level using a randomized controlled trial design.

Methods

This pragmatic, randomized, controlled, parallel-group clinical trial will compare the effectiveness of the motivational interviewing to an educational intervention, including the distribution of an information flyer as standard of care on vaccination coverage in four maternity wards across the Province of Québec (PromovaQ). Adult mothers of children born in participating maternity wards were recruited between March 2014 and February 2015. Vaccination coverage will be assessed at 3-years of age, thus the trial is expected to be completed in March 2019. Statistical analyses will be conducted under the intention-to-treat principle. Vaccine coverage will be analyzed using Chi-squared distribution testing and logistic regression to identify determinant factors. Secondary outcomes will include vaccine hesitation and intention scores, mother’s knowledge, attitudes and beliefs about immunization, and psychosocial determinants of intention to vaccinate.

Discussion

In the case results of this Provincial RCT be confirmed, serious consideration should then be given by Ministry of Health authorities to the possible implementation of MI-based strategies across provincial maternity wards. To ensure adequate input and secure implementation, study design and results will be reviewed with relevant stakeholders, including the children’s families, and provincial and regional decision-makers. Results will be adapted and shared with all stakeholders.

Trial registration

ClinicalTrials.gov NCT02666872 (Retrospectively registered as January 28, 2016).

Impact of vaccine delays at the 2, 4, 6 and 12 month visits on incomplete vaccination status by 24 months of age in Quebec, Canada

BACKGROUND

Timeliness in the administration of recommended vaccines is often evaluated using vaccine delays and provides more information regarding the susceptibility of children to vaccine-preventable diseases compared with vaccine coverage at a given age. The importance of on-time administration of vaccines scheduled at the first visit is well documented, but data are scarce about the impact of vaccine delays at other visits on vaccination status by 24 months of age. Using vaccine delays for the first three doses of DTaP-containing vaccines and for the first dose of measles-containing vaccines as markers of timeliness at the 2, 4, 6 and 12 month visits, we estimated the proportion of incomplete vaccination status by 24 months of age attributable to a vaccine delay at each of these visits.

METHODS

We used the data from six cross-sectional coverage surveys conducted in the Province of Quebec from 2006 to 2016 which included 7183 children randomly selected from the universal health insurance database. A vaccine dose was considered delayed if received 30 days or more after the recommended age. The impact of new vaccine delays at each visit on incomplete vaccination status by 24 months of age was estimated with the attributable risk in the population.

RESULTS

The proportion of children with vaccine delay was 5.4% at 2 months, 13.3% at 4 months, 23.1% at 6 months and 23.6% at 12 months. Overall, 72.5% of all 2-year-old children with an incomplete status by 24 months were attributable with a vaccine delay, of which 16.1% were attributable with a first vaccine delay at 2 months, 10.6% at 4 months, 14.0% at 6 months and 31.8% at 12 months.

CONCLUSIONS

While great emphasis has been put on vaccine delays at the first vaccination visit, the prevalence of vaccine delays was greater with later visits and most children with an incomplete vaccination status by 24 months had a vaccine delay occurring during these later visits. Interventions to improve timeliness should address vaccine delays at each visit and not only focus on the first visit.

Immunogenicity and safety of a mixed vaccination schedule with one dose of nonavalent and one dose of bivalent HPV vaccine versus two doses of nonavalent vaccine - A randomized clinical trial

BACKGROUND

Limited data is available on the use of different HPV vaccines in the same subjects. We evaluated the immunogenicity and safety of a mixed vaccination schedule with one dose of nonavalent (9vHPV) and one dose of bivalent vaccine (2vHPV) administered in different order versus two doses of 9vHPV vaccine.

METHODS

371 girls and boys aged 9-10 years were randomized (1:1) to receive (I) two doses of 9vHPV or (II) a mixed schedule of 2vHPV + 9vHPV or 9vHPV + 2vHPV with a 6 month interval. Antibodies to HPV were tested by ELISA in blood samples collected one or six months post-first dose and one month post-second dose.

RESULTS

Post-first dose of 9vHPV 99.4-100% of subjects were seropositive to 9 HPV types included in the vaccine. GMTs varied from 5.0 to 73.6 IU(AU)/ml depending on HPV type. Post-first dose of 2vHPV all subjects were seropositive to HPV16 and 18 (GMTs 16.7 and 11.7 IU/ml, respectively) and 50.0-76.7% were seropositive to 7 types not included in 2vHPV (GMTs varied from 0.3 to 17.5 AU/ml depending on type). Post-second dose all subjects, regardless of the study group, were seropositive to 9 HPV types included in 9vHPV. Anti-HPV16 and 18 GMTs were higher in subjects with the mixed schedule and for the other 7 HPV types higher in subjects who received two doses of 9vHPV vaccine. A higher proportion of subjects who received 2vHPV reported local or systemic adverse events than those who received 9vHPV as the first dose. Post-second dose there were no differences in reported adverse events between the two vaccines.

CONCLUSIONS

The results show the mixed HPV vaccination schedules used in this study are immunogenic and have an acceptable safety profile. Although the seroprotective threshold of antibodies remains unknown the 100% seropositivity to all 9 HPV types included in 9vHPV and the increase of GMTs observed in all study groups post-second dose administration are reassuring and suggest protection might be achieved regardless of the schedule used.

CLINICAL TRIALS REGISTRATION

Clinicaltrials.gov NCT02567955.

Antibody persistence after a single dose of quadrivalent HPV vaccine and the effect of a dose of nonavalent vaccine given 3-8 years later - an exploratory study

The objective of this study was to assess the persistence of antibodies after a single dose of quadrivalent HPV vaccine (4vHPV) and the effect of a dose of nonavalent HPV vaccine (9vHPV) given 3–8 years later. Such data might be of interest in the decision-making process regarding the 2-dose course completion in non-compliant vaccinees in jurisdictions which switched from 4vHPV to 9vHPV. Girls who previously received a single dose of 4vHPV were eligible to participate. Blood specimens were collected just before and one month post-9vHPV administration. The specimens were tested by ELISA for the presence of antibodies to 9 HPV types included in the 9vHPV. Thirty-one girls aged 13–18 years (mean 15.5 years) participated in the study. Pre-9vHPV administration, all participants were seropositive to 4 HPV types included in 4vHPV and 58%-87% were seropositive to the five other HPV types included in the 9vHPV. GMTs were 6.1 AU/ml, 7.7 AU/ml, 20.1 IU/ml and 6.3 IU/ml to HPV6, HPV11, HPV16 and HPV18, respectively. The GMTs for the other five HPV types varied from 1.0 to 2.9 AU/ml. One month post-9vHPV administration all 31 participants were seropositive to all 9 HPV types with a 36.1 to 89.1-fold increase of GMTs. High seropositivity rates observed several years after a single dose of 4vHPV and 100% seropositivity after a dose of 9vHPV suggest that this schedule might be used in non-compliant vaccinees or when switching immunization programs from 4vHPV to 9vHPV.

Overview of knowledge, attitudes, beliefs, vaccine hesitancy and vaccine acceptance among mothers of infants in Quebec, Canada

BACKGROUND

Vaccine hesitancy (VH) is a growing problem. The first step in addressing VH is to have an understanding of who are the hesitant individuals and what are their specific concerns. The aim of this survey was to assess mothers' level of vaccine hesitancy and vaccination knowledge, attitudes, and beliefs.

METHODS

Mothers of newly-born infants in four maternity wards in Quebec (Canada) completed a self-administered questionnaire. The questionnaire included items to assess VH and intention to vaccinate. VH scores were calculated using the Parents Attitudes about Childhood Vaccines (PACV) survey. Multivariate logistic regression was performed to determine variables associated with intention to vaccinate (OR; 95% CI).

RESULTS

Overall, 2645 questionnaires were included in this analysis and 77.5% of respondents certainly intended to vaccinate their infant at 2 months of age. Based on the PACV 100-point scale, 56.4% of mothers had a 0 to ˂30 score (low level of VH); 28.6% had a 30 to ˂50 and 15.0% had a score of 50 and higher (high level of VH).The main determinants of mothers' intention to vaccinate were the perceived importance of vaccinating infants at 2 months of age (OR = 9.2; 5.9-14.5) and a low score of VH (OR = 7.4; 5.3-10.3).

DISCUSSION

Although the majority of mothers held positive attitudes toward vaccination, a large proportion were moderately or highly vaccine hesitant. Mothers' level of VH was strongly associated with their intention to vaccinate their infants, showing the potential detrimental impact of VH on vaccine uptake rates and the importance of addressing this phenomenon.

Early use of the HPV 2-dose vaccination schedule: Leveraging evidence to support policy for accelerated impact

Although human papillomavirus (HPV) vaccines were initially licensed based on efficacy after three-dose regimens in women aged 15-26 years, it was recognized early in clinical development that comparable immunogenicity could be obtained after just two doses when administered to younger girls. In both Canada and Mexico, public health authorities made the decision to administer two doses 6 months apart with a planned additional dose at 60 months, while simultaneously doing further study to determine if the third dose would confer meaningful additional benefit. This delayed third dose approach permitted a more cost-effective program with opportunities for improved compliance while minimizing injections and leaving open the opportunity to provide a full three-dose vaccination series. It required close cooperation across many governmental and civil society leadership bodies and real-time access to emerging data on HPV vaccine effectiveness. Although still limited, there is increasing evidence that even one-dose vaccination is sufficient to provide prolonged protection against HPV infection and associated diseases. Ongoing clinical trials and ecological studies are expected to consolidate existing data regarding one dose schedule use. However, to accelerate the preventive effect of HPV vaccination some jurisdictions, in particular those with limited resources may already consider the initiation of a one dose vaccination with the possibility of giving the second dose later in life if judged necessary. Such an approach would facilitate vaccination implementation and might permit larger catch-up vaccination programs in older girls (or as appropriate, girls and boys), thereby accelerating the impact on cervical cancer and other HPV-associated diseases.

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.

Absence of association between Guillain-Barré syndrome hospitalizations and HPV-vaccine

BACKGROUND

In 2008, a school-based human papilloma virus (HPV) vaccination program was implemented in the province of Québec. Grade 4 girls (9-10 years old) are routinely vaccinated and grade 9 to 12 girls (14-17 years old) were eligible for the catch-up vaccination. Vaccine coverage of the targeted cohorts was estimated at 76-81%. To assess if HPV vaccination is associated with an increase in GBS hospitalisation, we compared the hospitalization rates of GBS in HPV vaccination targeted and non-targeted groups.

METHODS

Hospital discharge records with a GBS code as the main diagnosis during the 1999-2014 period were retrieved. Incidence rates according to program eligibility were computed and adjusted relative risk in the targeted groups was estimated by Poisson regression.

RESULTS

The overall incidence rate in the 7 to 17 year-olds was 0.73/100,000 p-y. There was no increase in GBS incidence in HPV vaccination targeted groups (adjusted IRR = 0.81, 95%CI: 0.29-2.26).

CONCLUSION

No signal of increase GBS hospitalisation incidence in the HPV-vaccine targeted group was detected in the hospitalisation database.

"Nature Does Things Well, Why Should We Interfere?": Vaccine Hesitancy Among Mothers

Parents' decision to use vaccination services is complex and multi-factorial. Of particular interest are "vaccine-hesitant" parents who are in the middle of the continuum between vaccine acceptance and refusal. The objective of this qualitative longitudinal study was to better understand why mothers choose to vaccinate-or not-their newborns. Fifty-six pregnant mothers living in different areas of Quebec (Canada) were interviewed. These interviews gathered information on mothers' views about health and vaccination. Almost half of the mothers were categorized as vaccine-hesitant. A second interview was conducted with these mothers 3 to 11 months after birth to look at their actual decision and behavior concerning vaccination. Our results show the heterogeneity of factors influencing vaccine decision making. Although the majority of vaccine-hesitant mothers finally chose to follow the recommended vaccine schedule for their child, they were still ambivalent and they continued to question their decision.

HPV vaccination for MSM: Synthesis of the evidence and recommendations from the Québec Immunization Committee

Diseases associated with the human papilloma virus (HPV) are particularly common among men who have sex with men (MSM). Unlike heterosexual men, MSM do not benefit from the herd protection provided by the vaccination of girls. In this review, we synthesize the available evidence on HPV vaccination for MSM. We also present the recommendations of the Québec Immunization Committee (CIQ) in this regard, which are: to provide targeted vaccination for MSM up to 26 years of age and in-school vaccination of preadolescent boys since this is the best approach to take to have a real impact on the burden related to HPV in the MSM population and to provide direct protection for all men.

Immunogenicity of quadrivalent HPV and combined hepatitis A and B vaccine when co-administered or administered one month apart to 9-10 year-old girls according to 0-6 month schedule

BACKGROUND

No immunogenicity data has been reported after a single dose of the quadrivalent HPV vaccine (qHPV-Gardasil®) and no data are available on co-administration of this vaccine with the HAV/HBV vaccine (Twinrix-Junior®). Two pre-licensure studies reported similar anti-HPV but lower anti-HBs titers when co-administering HPV and HBV vaccines.

OBJECTIVES

To assess the immunogenicity of the qHPV and HAV/HBV vaccine when co-administered (Group-Co-adm) or given one month apart (Group-Sep) and to measure the persistence of HPV antibodies three years post-second dose of qHPV vaccine in both study groups.

METHODS

416 9-10 year-old girls were enrolled. Vaccination schedule was 0-6 months. Anti-HAV and anti-HBs were measured in all subjects 6 months post-first dose and 1 month post-second dose. Anti-HPV were measured 6 months post-first dose in Group-Co-adm and in all subjects 1 and 36 months post-second dose.

RESULTS

Six months post-first dose: 100% of subjects had detectable anti-HAV and 56% and 73% had detectable anti-HBs in Group-Co-Adm and Group-Sep, respectively. In Group-Co-adm 94, 100, 99 and 96% had detectable antibodies to HPV 6, 11, 16 and 18, respectively. One month post-second dose of qHPV and HAV/HBV vaccine, in both study groups 99.5-100% of subjects had an anti-HAV titer ≥ 20IU/L, 97.5-97.6% an anti-HBs level ≥ 10IU/L, and 100% had an anti-HPV titer ≥ 3LU. Thirty-six months post-second dose of qHPV all but four subjects (99%) had antibodies to HPV18 and 100% had antibodies to HPV6, 11 and 16. The great majority (97-100%) had an anti-HPV titer ≥ 3 LU. Post-second dose administration of qHPV and HAV/HBV, no meaningful difference was observed in the immune response in the two study groups to any component of vaccines.

CONCLUSIONS

The results indicate that qHPV and HAV/HBV can be given during the same vaccination session. Two doses of of qHPV and HAV/HBV vaccines induce a strong immune response. Three years post-second dose of qHPV, the great majority of subjects had antibodies to HPV types included in the vaccine. A two-dose schedule for pre-adolescents might be a reasonable alternative to the currently approved three-dose schedules.

The effect of a booster dose of quadrivalent or bivalent HPV vaccine when administered to girls previously vaccinated with two doses of quadrivalent HPV vaccine

This randomized, blinded study evaluated the immunogenicity and safety of a booster dose of Gardasil (qHPV) or Cervarix (bHPV) when administered to 12-13 year-old girls who were vaccinated at the age of 9-10 with 2 doses of qHPV (0-6 months). 366 out of 416 eligible girls participated in this follow-up study. Antibody titers were measured just before and one month post-booster. A Luminex Total IgG assay was used for antibody assessment and results are presented in Liminex Units (LU). Three years post-primary vaccination, 99-100% of subjects had detectable antibodies to 4HPV genotypes included in the qHPV with GMTs varying from 50 to 322 LU depending on genotype. After a booster dose of qHPV, a ≥4 fold increase of antibody titers to genotypes included in the vaccine was observed in 88-98% of subjects. Post-booster GMTs varied from 1666 to 4536 LU depending on genotype. These GMTs were 1.1 to 1.8-fold higher when compared to those observed one month post-second dose. After a booster of bHPV, a ≥4 fold increase of antibody titers to HPV16 and HPV18 was observed in 93-99% of subjects. The anti-HPV16 and HPV18 GMTs were 5458 and 2665 LU, respectively. These GMTs were 1.2 and 1.8 higher than those observed in the qHPV group (both P < 0.01). In bHPV group a 1.4-1.6-fold increase of antibody GMTs to HPV6 and HPV11was also observed (P < 0.001). The safety profile was acceptable for both vaccines. Both qHPV and bHPV increase antibody titers when given as a booster to girls previously vaccinated with 2 doses of qHPV. The magnitude of the immune response after booster is vaccine-dependent and has the same pattern as that reported after primary vaccination with qHPV or bHPV. When given as a booster, both vaccines have an acceptable safety profile. Longer follow-up studies are warranted to assess the need of booster doses.

Comparing the cost-effectiveness of two- and three-dose schedules of human papillomavirus vaccination: a transmission-dynamic modelling study

BACKGROUND

Recent evidence suggests that two doses of HPV vaccines may be as protective as three doses in the short-term. We estimated the incremental cost-effectiveness of two- and three-dose schedules of girls-only and girls & boys HPV vaccination programmes in Canada.

METHODS

We used HPV-ADVISE, an individual-based transmission-dynamic model of multi-type HPV infection and diseases (anogenital warts, and cancers of the cervix, vulva, vagina, anus, penis and oropharynx). We conducted the analysis from the health payer perspective, with a 70-year time horizon and 3% discount rate, and performed extensive sensitivity analyses, including duration of vaccine protection and vaccine cost.

FINDINGS

Assuming 80% coverage and a vaccine cost per dose of $85, two-dose girls-only vaccination (vs. no vaccination) produced cost/quality-adjusted life-year (QALY)-gained varying between $7900-24,300. The incremental cost-effectiveness ratio of giving the third dose to girls (vs. two doses) was below $40,000/QALY-gained when: (i) three doses provide longer protection than two doses and (ii) two-dose protection was shorter than 30 years. Vaccinating boys (with two or three doses) was not cost-effective (vs. girls-only vaccination) under most scenarios investigated.

INTERPRETATION

Two-dose HPV vaccination is likely to be cost-effective if its duration of protection is at least 10 years. A third dose of HPV vaccine is unlikely to be cost-effective if two-dose duration of protection is longer than 30 years. Finally, two-dose girls & boys HPV vaccination is unlikely to be cost-effective unless the cost per dose for boys is substantially lower than the cost for girls.

Seasonal influenza vaccination uptake in Quebec, Canada, 2 years after the influenza A(H1N1) pandemic

BACKGROUND

A decrease in seasonal influenza vaccine uptake was observed after the influenza A(H1N1) pandemic in 2009. The goal of our study was to assess seasonal influenza vaccine uptake in 2011-2012, 2 years after the influenza A(H1N1) pandemic mass immunization campaign and to identify the main reasons for having or not having received the vaccine.

METHODS

A telephone survey using random-digit dialing methodology was conducted. Case-weights were assigned to adjust for disproportionate sampling and for nonresponse bias. Descriptive statistics were generated for all variables.

RESULTS

Seasonal influenza vaccine uptake was 57% among adults aged ≥60 years, 35% among adults with chronic medical conditions, and 44% among health care workers. The main reasons given for having been vaccinated were to be protected from influenza and a high perceived susceptibility to influenza, whereas low perceived susceptibility to influenza and low perceived severity of influenza were the main reasons for not having been vaccinated.

CONCLUSIONS

An increase in seasonal influenza vaccine uptake was observed 2 years after the influenza A(H1N1) pandemic. However, vaccine coverage is still below the target level of 80%. More efforts are needed to develop effective strategies to increase seasonal influenza vaccine uptake.

How do Midwives and Physicians Discuss Childhood Vaccination with Parents?

Even if vaccination is often described as one of the great achievements of public health, results of recent studies have shown that parental acceptance of vaccination is eroding. Health providers' knowledge and attitudes about vaccines are important determinants of their own vaccine uptake, their intention to recommend vaccines to patients and the vaccine uptake of their patients. The purpose of this article is to compare how midwives and physicians address vaccination with parents during pregnancy and in postpartum visits. Thirty semi-structured interviews were conducted with midwives and physicians practicing in the province of Quebec, Canada. Results of our analysis have shown that physicians adopt an "education-information" stance when discussing vaccination with parents in the attempt to "convince" parents to vaccinate. In contrast, midwives adopted a neutral stance and gave information on the pros and cons of vaccination to parents while leaving the final decision up to them. Findings of this study highlight the fact that physicians and midwives have different views regarding their role and responsibilities concerning vaccination. It may be that neither of these approaches is optimal in promoting vaccination uptake.

Immunization services offered in Québec (Canada) pharmacies

Canadian Pharmacists are easy to reach. Although Québec pharmacists are not allowed to administer vaccines, they can: (1) promote vaccination, (2) counsel patients on vaccination, (3) sell vaccines and (4) provide vaccine administration by a nurse. Our objectives were to describe immunization services given in Québec pharmacies and assess the potential relation between, on one hand, pharmacy characteristics and difficulties perceived by pharmacists and, on the other hand, vaccine administration. In 2008-09, an anonymous questionnaire was mailed to all Québec pharmacy owners (n = 1663). Among the 1102 (66%) respondents, 90% stated that vaccines were sold, 27% that a nurse administered vaccines in their pharmacy and 44% were planning to offer vaccine administration in the next five years. Three out of four stated they were doing vaccine promotion and 65%, vaccine counselling. Half of respondents said they would be willing to administer vaccines themselves if legislative modifications were made. Recommendations for cold chain maintenance were followed in 23% of pharmacies selling vaccines. Presence of another health professional in the pharmacy, higher number of opening hours, not being located in the same building than a medical clinic and having an agreement to collaborate with a public health unit or a medical clinic for immunization were positively associated with vaccine administration in multivariate analysis. Higher perceived difficulties with lack of demand from patients were negatively associated with vaccine administration. Most pharmacists are willing to increase their involvement in immunization. Collaboration between public health professionals and pharmacists should be reinforced.

Immunogenicity of 2 doses of HPV vaccine in younger adolescents vs 3 doses in young women: a randomized clinical trial

IMPORTANCE

Global use of human papillomavirus (HPV) vaccines to prevent cervical cancer is impeded by cost. A 2-dose schedule for girls may be possible.

OBJECTIVE

To determine whether mean antibody levels to HPV-16 and HPV-18 among girls receiving 2 doses was noninferior to women receiving 3 doses.

DESIGN, SETTING, AND PATIENTS

Randomized, phase 3, postlicensure, multicenter, age-stratified, noninferiority immunogenicity study of 830 Canadian females from August 2007 through February 2011. Follow-up blood samples were provided by 675 participants (81%).

INTERVENTION

Girls (9-13 years) were randomized 1:1 to receive 3 doses of quadrivalent HPV vaccine at 0, 2, and 6 months (n = 261) or 2 doses at 0 and 6 months (n = 259). Young women (16-26 years) received 3 doses at 0, 2, and 6 months (n = 310). Antibody levels were measured at 0, 7, 18, 24, and 36 months.

MAIN OUTCOMES AND MEASURES

Primary outcome was noninferiority (95% CI, lower bound >0.5) of geometric mean titer (GMT) ratios for HPV-16 and HPV-18 for girls (2 doses) compared with young women (3 doses) 1 month after last dose. Secondary outcomes were noninferiority of GMT ratios of girls receiving 2 vs 3 doses of vaccine; and durability of noninferiority to 36 months.

RESULTS

The GMT ratios were noninferior for girls (2 doses) to women (3 doses): 2.07 (95% CI, 1.62-2.65) for HPV-16 and 1.76 (95% CI, 1.41-2.19) for HPV-18. Girls (3 doses) had GMT responses 1 month after last vaccination for HPV-16 of 7736 milli-Merck units per mL (mMU/mL) (95% CI, 6651-8999) and HPV-18 of 1730 mMU/mL (95% CI, 1512-1980). The GMT ratios were noninferior for girls (2 doses) to girls (3 doses): 0.95 (95% CI, 0.73-1.23) for HPV-16 and 0.68 (95% CI, 0.54-0.85) for HPV-18. The GMT ratios for girls (2 doses) to women (3 doses) remained noninferior for all genotypes to 36 months. Antibody responses in girls were noninferior after 2 doses vs 3 doses for all 4 vaccine genotypes at month 7, but not for HPV-18 by month 24 or HPV-6 by month 36.

CONCLUSIONS AND RELEVANCE

Among girls who received 2 doses of HPV vaccine 6 months apart, responses to HPV-16 and HPV-18 one month after the last dose were noninferior to those among young women who received 3 doses of the vaccine within 6 months. Because of the loss of noninferiority to some genotypes at 24 to 36 months in girls given 2 doses vs 3 doses, more data on the duration of protection are needed before reduced-dose schedules can be recommended.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00501137.

Factors associated with HPV vaccination among adult women in Quebec

BACKGROUND AND OBJECTIVE

Human papillomavirus (HPV) infections are the most common sexually transmitted infections in North America and are associated with cervical cancer. A publicly-funded HPV immunization program was launched in the province of Quebec, Canada, in the fall of 2008. The aim of this study was to explore factors associated with HPV immunization among young adult women not targeted by this program.

METHODS

A questionnaire was mailed to 2400 24-y-old women randomly selected from the Quebec provincial health insurance database and 56% responded. Factors associated with vaccination status were analyzed using a multivariate logistic regression model.

RESULTS

Few women had received at least one dose of HPV vaccine among the 1347 respondents. Age at first sexual intercourse ≥ 20 y, participating in cervical cancer screening, higher education level, being born in Quebec and some positive beliefs about HPV were associated with vaccination.

CONCLUSIONS

The rate of immunization in women who had to pay for the HPV vaccine was very low and was associated with characteristics that are generally associated with a lower risk for HPV infection and cervical cancer. Efforts are needed to reach at-risk adult women.

[Knowledge and attitudes toward vaccination among midwives in Quebec]

OBJECTIVES

Vaccine acceptability among Quebec midwives is not well documented. The purpose of this study was to examine midwives' knowledge, attitudes and practices relating to immunization in Quebec.

METHODS

Semi-structured interviews were conducted with 25 participants (17 midwives and 8 midwifery students). The mean duration of the interviews was 1 hour. The interviews were conducted in 2010 and were audiotaped, transcribed and submitted to content analysis using NVivo 8 software.

RESULTS

In addition to the laws regulating midwifery practice in Quebec, the findings suggest that most midwifery interventions are based on midwifery philosophy. Informed choice is one of the key principles of this philosophy. In order to help women make an informed decision about vaccination, midwives seek to outline the pros and cons of vaccination using government documentation, as well as other sources such as books on naturopathy. Most of the participating midwives recognized that vaccination has advantages, including disease prevention and free vaccines. Various arguments against vaccination were also identified. Most of these were related to the vaccination schedule and to combined vaccines. Some of the participants noted that it was difficult to find unbiased information about vaccination.

CONCLUSION

This study highlights the key role of midwifery philosophy in midwifery practice. Most decisions (such as vaccination) are made on the basis of the principle of informed choice. Most of the participants noted that they lacked information on vaccination.

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.