Identification of determinants associated with uptake of the first dose of the human papillomavirus vaccine in Denmark

Exploration of individual socioeconomic and health-related characteristics associated with human papillomavirus vaccination initiation and vaccination series completion among adult females: A comprehensive systematic evidence review with meta-analysis

INTRODUCTION

Human papillomavirus (HPV) vaccination rates among females are lower than the World Health Organization target and vaccination rates specifically among adult females are even much lower.

METHODS

We systematically evaluated individual socioeconomic and health-related characteristics associated with HPV vaccination initiation and vaccination series completion among adult females (PROSPERO: CRD42023445721). We performed a literature search on December 14, 2022, and supplemented the search on August 1, 2023. We pooled appropriate multivariable-adjusted results using an inverse variance random-effects model and expressed the results as odds ratios with associated 95 % confidence intervals. A point pooled significantly increased/decreased odds of 30-69 % was regarded to be strongly associated, and ≥ 70 % was very strongly associated.

RESULTS

We included 63 cross-sectional studies. There were strongly increased odds of vaccination initiation among White women compared with Black or Asian women, and those with higher education, health insurance, a history of sexually transmitted infection (STI), receipt of influenza vaccination in the preceding year, not married/cohabiting, not smoking, using contraception, and having visited a healthcare provider in the preceding year. We observed very strongly increased odds of vaccination initiation among those younger and having been born in the country of study. Similarly, there were strongly increased odds of completing the vaccination series for the same variables as initiating vaccination, except for higher education, prior STI, smoking and contraception use. Additional variables associated with strongly increased odds of vaccination series completion not seen in initiation were higher annual household income, being lesbian/bisexual, and having a primary care physician. We observed very strongly increased odds of vaccination series completion similar to vaccination initiation but including for White compared with Black women, higher education, and prior cervical cancer screening.

CONCLUSIONS

These individual characteristics may be the key to identifying women at increased risk of not being vaccinated against HPV and could inform targeted messaging to drive HPV vaccination.

Sibling spillovers and the choice to get vaccinated: Evidence from a regression discontinuity design

We investigate the effects of introducing population-wide free-of-charge Human Papillomavirus (HPV) vaccination programs on the targeted adolescent cohorts and their siblings. For identification, we rely on regression discontinuity designs and high-quality Danish administrative data to exploit that date of birth determines program eligibility. We find that the programs increased the HPV vaccine take-up of both the targeted children (53.2 percentage points for girls and 36.0 percentage points for boys) and their older same-sex siblings (4.5 percentage points for sisters and 3.5 percentage points for brothers). We show that while the direct effects of the programs reduced HPV vaccine take-up inequality, the spillover effects, in contrast, contributed to an increase in vaccine take-up inequality highlighting the potential importance of spillover effects in the determination of distributional consequences of public health programs. Finally, we find some evidence of cross-vaccine spillovers.

Characteristics associated with non-initiation and non-completion of human papillomavirus vaccination among Danish girls: a nationwide register-based cohort study

AIM

The aim was to identify maternal and paternal socioeconomic and demographic characteristics for non-initiation and non-completion of the human papillomavirus (HPV) vaccination among Danish girls including time-trends.

METHODS

This nationwide register-based cohort study included all girls residing in Denmark who were offered free-of-charge HPV vaccination as a part of the childhood vaccination program between 2009 and 2018 (birth cohorts 1996-2005). The study samples included 296,461 daughter-mother dyads and 291,025 daughter-father dyads. Data from the Danish Vaccination Register were linked with socioeconomic and demographic data from Statistics Denmark. HPV vaccination status was classified as 'non-initiation' for girls who received no HPV vaccine and as 'non-completion' for girls who initiated the HPV vaccination program but did not receive all the scheduled HPV vaccines. Data were analyzed using logistic regression models.

RESULTS

Non-initiation of HPV vaccination was 13.7%, and non-completion was 24.2% among girls who initiated the HPV vaccination program. Girls of parents who were descendants of immigrants (adjusted odds ratio: 1.50; 95% confidence interval: 1.35-1.68), were at least 35-years old at time of birth, had basic or no education, had a low income, were not in the labor market, and were unmarried had the highest non-initiation and non-completion odds. The associations between socioeconomic and demographic characteristics and HPV vaccination uptake were similar for mothers and fathers.

CONCLUSIONS

Despite free-of-charge availability to HPV vaccination in Denmark, we found disparities in non-initiation and non-completion of HPV vaccination among Danish girls by both mothers' and fathers' socioeconomic and demographic characteristics.

Age, gender and socioeconomic disparities in human papillomavirus (HPV) awareness and knowledge among Japanese adults after a 7-year suspension of proactive recommendation for the HPV vaccine: A nationally representative cross-sectional survey

The Japanese government's 2013 suspension of its proactive recommendation for Human papillomavirus (HPV) vaccination resulted in low HPV vaccination coverage and was unique. However, data on awareness and knowledge of HPV vaccines in the general population was limited. Here, to investigate more recent awareness and knowledge of HPV vaccines by age, gender, and socioeconomic status, we used data from the INFORM Study 2020, a nationally representative cross-sectional survey of self-administered questionnaires with 1,998 Japanese individuals aged 20 to 59 years. We found that 47.5% of females and 21.0% of males had heard of HPV, and 33.6% of females and 16.8% of males had knowledge of HPV vaccine efficacy. After adjusting for potential confounders, females aged 50-54 years were more likely to be aware of HPV than females aged 20-24 (AOR, 2.02, 95%CI: 1.12-3.65). Females (AOR, 2.13, 95%CI: 1.48-3.07) and males (AOR, 1.64, 95%CI: 1.03-2.59) with higher education had more awareness than those with less education. Females with higher education had more knowledge about HPV vaccine efficacy than those with less education (AOR, 1.70; 95%CI: 1.16-2.50). We found a generally low level of awareness and knowledge about HPV vaccines in Japan, which might be attributable to the suspension of proactive recommendations. Additionally, we identified disparities in awareness and knowledge by age, gender, socioeconomic status, and health literacy. Enhancing HPV awareness and understanding of HPV vaccines and implementing targeted efforts for specific subpopulations within Japan after the resumption of proactive recommendation for HPV vaccines, are imperative.

Identification of subgroups in the Danish population for targeted human papillomavirus vaccination efforts

BACKGROUND

In the Danish childhood vaccination program, the human papillomavirus (HPV) vaccination coverage is lower than for other vaccines. To tailor a targeted HPV vaccination effort, we aimed to identify girls in Denmark with lower first dose HPV vaccination coverage than girls in general.

METHODS

A population-based retrospective cohort study was performed of girls born in 2001-2004, residing in Denmark in September 2019 (N = 128,351). Data from the Danish Vaccination Register was linked to sociodemographic data from the Danish Civil Registration System and Statistics Denmark. Cox's proportional hazard regression models were used to compare vaccination uptake rates between subgroups of girls.

RESULTS

HPV vaccination coverage at 14 years of age varied widely by municipality (53.4-80.6%). Girls living with neither of their parents had a lower chance of being vaccinated compared to girls living with both their parents (HR 0.43; 95% CI 0.41-0.46), likewise for girls attending special need education compared with girls attending public schools (HR 0.50; 95% CI 0.42-0.59). The vaccination uptake among immigrants was lower compared to Danish-born girls (HR 0.51; 95% CI 0.49-0.54), especially among immigrant girls whose parents had not passed any Danish exams. Finally, girls who were DTaP-IPV revaccinated had a 50% greater chance of being HPV vaccinated compared to girls who were not (HR 1.61; 95% CI 1.58-1.64).

CONCLUSION

To increase the HPV vaccination uptake, we recommend vaccination efforts targeting girls living without any of their parents, girls attending special need education, immigrants, and girls who are not DTaP-IPV revaccinated. When targeting immigrants, the effort should focus on disseminating sufficient and understandable information about the Danish childhood vaccination program to the parents.

Defining the determinants of vaccine uptake and undervaccination in migrant populations in Europe to improve routine and COVID-19 vaccine uptake: a systematic review

Understanding why some migrants in Europe are at risk of underimmunisation and show lower vaccination uptake for routine and COVID-19 vaccines is critical if we are to address vaccination inequities and meet the goals of WHO's new Immunisation Agenda 2030. We did a systematic review (PROSPERO: CRD42020219214) exploring barriers and facilitators of vaccine uptake (categorised using the 5As taxonomy: access, awareness, affordability, acceptance, activation) and sociodemographic determinants of undervaccination among migrants in the EU and European Economic Area, the UK, and Switzerland. We searched MEDLINE, CINAHL, and PsycINFO from 2000 to 2021 for primary research, with no restrictions on language. 5259 data sources were screened, with 67 studies included from 16 countries, representing 366 529 migrants. We identified multiple access barriers-including language, literacy, and communication barriers, practical and legal barriers to accessing and delivering vaccination services, and service barriers such as lack of specific guidelines and knowledge of health-care professionals-for key vaccines including measles-mumps-rubella, diphtheria-pertussis-tetanus, human papillomavirus, influenza, polio, and COVID-19 vaccines. Acceptance barriers were mostly reported in eastern European and Muslim migrants for human papillomavirus, measles, and influenza vaccines. We identified 23 significant determinants of undervaccination in migrants (p<0·05), including African origin, recent migration, and being a refugee or asylum seeker. We did not identify a strong overall association with gender or age. Tailored vaccination messaging, community outreach, and behavioural nudges facilitated uptake. Migrants' barriers to accessing health care are already well documented, and this Review confirms their role in limiting vaccine uptake. These findings hold immediate relevance to strengthening vaccination programmes in high-income countries, including for COVID-19, and suggest that tailored, culturally sensitive, and evidence-informed strategies, unambiguous public health messaging, and health system strengthening are needed to address access and acceptance barriers to vaccination in migrants and create opportunities and pathways for offering catch-up vaccinations to migrants.

Defining the determinants of vaccine uptake and undervaccination in migrant populations in Europe to improve routine and COVID-19 vaccine uptake: a systematic review

Understanding why some migrants in Europe are at risk of underimmunisation and show lower vaccination uptake for routine and COVID-19 vaccines is critical if we are to address vaccination inequities and meet the goals of WHO's new Immunisation Agenda 2030. We did a systematic review (PROSPERO: CRD42020219214) exploring barriers and facilitators of vaccine uptake (categorised using the 5As taxonomy: access, awareness, affordability, acceptance, activation) and sociodemographic determinants of undervaccination among migrants in the EU and European Economic Area, the UK, and Switzerland. We searched MEDLINE, CINAHL, and PsycINFO from 2000 to 2021 for primary research, with no restrictions on language. 5259 data sources were screened, with 67 studies included from 16 countries, representing 366 529 migrants. We identified multiple access barriers-including language, literacy, and communication barriers, practical and legal barriers to accessing and delivering vaccination services, and service barriers such as lack of specific guidelines and knowledge of health-care professionals-for key vaccines including measles-mumps-rubella, diphtheria-pertussis-tetanus, human papillomavirus, influenza, polio, and COVID-19 vaccines. Acceptance barriers were mostly reported in eastern European and Muslim migrants for human papillomavirus, measles, and influenza vaccines. We identified 23 significant determinants of undervaccination in migrants (p<0·05), including African origin, recent migration, and being a refugee or asylum seeker. We did not identify a strong overall association with gender or age. Tailored vaccination messaging, community outreach, and behavioural nudges facilitated uptake. Migrants' barriers to accessing health care are already well documented, and this Review confirms their role in limiting vaccine uptake. These findings hold immediate relevance to strengthening vaccination programmes in high-income countries, including for COVID-19, and suggest that tailored, culturally sensitive, and evidence-informed strategies, unambiguous public health messaging, and health system strengthening are needed to address access and acceptance barriers to vaccination in migrants and create opportunities and pathways for offering catch-up vaccinations to migrants.

HPV Vaccination Coverage Rate in a Rural Area: An Observational, Retrospective, and Cohort Study

In order to reduce the incidence and mortality rate of cervical cancer, the World Health Organization (WHO) declared the Global Strategy Goal for 2030, advocating for reaching a vaccination coverage rate of >90% against human papillomavirus for girls by the age of 15 years. The main objectives of this study were (1) to determine the papillomavirus vaccination coverage among women 15−40 years old and (2) to identify the at-risk subgroups and possible barriers to achieving WHO’s 2030 goal. Multicentre, observational, retrospective, and community-based cohort studies were conducted on women from a rural area in southern Catalonia until 31 December 2021. A total of 23,136 women were included, with a mean age of 26.6 (SD = 5.6) years. The average dose number was 1.7 (SD = 0.7). The results showed overall vaccination coverage of 17.4% among the target women. This coverage was unequal across regions (16.6−24.5%, p < 0.001), primary healthcare teams (15.5−24.3%, p < 0.001), and age groups (56.7% (15−19-year-olds) vs. 3.8% (35−40-year-olds), p < 0.001), related to accessibility to vaccination and economic−geographical indicators. Clinical practice guidelines on screening individuals at risk in terms of vaccination access and public vaccination protocols should be implemented in order to improve the vaccination coverage rate.

Sex and age as determinants of the seroprevalence of anti-measles IgG among European healthcare workers: A systematic review and meta-analysis

INTRODUCTION

The international literature shows good evidence of a significant rate of measles susceptibility among healthcare workers (HCWs). As such, they are an important public health issue.

METHODS

We conducted a systematic review and meta-analysis to estimate the prevalence of susceptible HCWs in EU/EEA countries and in the UK and to explore the characteristics (sex and age differences) and management of those found to be susceptible.

RESULTS

Nineteen studies were included in the meta-analysis. The prevalence of measles-susceptible HCWs was 13.3% (95 %CI: 10.0-17.0%). In a comparison of serosusceptible female vs. male HCWs, the RR was 0.92 (95 %CI = 0.83-1.03), and in a comparison of age classes (born after vs. before 1980) the RR was 2.78 (95 %CI = 2.20-3.50). The most recent studies proposed the mandatory vaccination of HCWs.

DISCUSSION

According to our meta-analysis, the prevalence of serosusceptible European HCWs is 13%; HCWs born in the post-vaccination era seem to be at higher risk. Healthcare professionals susceptible to measles are a serious epidemiological concern. Greater efforts should therefore be made to identify those who have yet to be vaccinated and actively encourage their vaccination.

Parents' reasoning about HPV vaccination in Sweden

INTRODUCTION

The aim of this study was to describe parents' reasoning in making decisions about vaccinating their daughters against human papilloma virus (HPV), a part of the Swedish vaccination programme.

METHOD

Twenty parents whose daughter had been offered HPV vaccination participated. Semi-structured individual interviews were conducted and analysed using thematic analysis.

RESULTS

The findings reveal that the decision-making process is complex. The parents trusted the vaccination programme and saw it as beneficial to society. They also described using different resources to decide about HPV vaccination, but they did not include their daughters in making the decision.

DISCUSSION

Parents need better vaccine and health literacy to be able to decide, based on evidence and in consultation with their daughters, on HPV vaccination. School nurses can play an important role in evidence-based decision-making about HPV vaccination and introducing children to this health-promoting intervention.

Human papillomavirus vaccination in immigrants and descendants of immigrants in Denmark

OBJECTIVE

In Denmark, human papillomavirus (HPV) vaccination has been offered at age of 12 to girls born in 1996 and later. In this cohort study, we examined routine HPV vaccination uptake in immigrants and descendants from different countries and regions compared with native Danes, including the influence of socioeconomic characteristics and potential changes in uptake by birth cohort.

METHODS

In nationwide registers, we identified all girls born in 1996-2003 (n = 260 251) and obtained information on country of origin, HPV vaccinations and parents' income and employment. Vaccination was defined as receiving ≥1 dose within 2 years after eligibility for routine vaccination. Odds ratios (ORs) were estimated by logistic regression separately for birth cohorts 1996-2000 and 2001-2003.

RESULTS

Uptake in immigrants and descendants varied by country and region of origin. Overall, immigrants had lower uptake than native Danes, in birth cohorts 1996-2000 [79% vs. 93%, OR = 0.31; 95% confidence interval (CI), 0.29-0.34] and 2001-2003 (63% vs. 73%, OR = 0.60; 95% CI, 0.54-0.66). Descendants had lower uptake than native Danes in cohorts 1996-2000 (89% vs. 93%, OR = 0.65; 95% CI, 0.60-0.68), but higher uptake in cohorts 2001-2003 (76% vs. 73%, OR = 1.15; 95% CI, 1.08-1.21). Most associations were attenuated, but not entirely explained, when adjusting for socioeconomic characteristics.

CONCLUSION

HPV vaccination uptake varied by country and region. Most immigrants had lower uptake than native Danes, and in most groups, this was not fully explained by socioeconomic differences. Patterns in descendants were mixed. Interventions to increase uptake should be tailored to specific groups of immigrants/descendants.

Vaccine Hesitancy and Differential Susceptibility to Media Coverage: A Critical Documentary Led to Substantial Reductions in Human Papillomavirus Vaccine Uptake in Denmark

OBJECTIVES

To investigate whether negative media coverage of the human papillomavirus (HPV) vaccine led to a decrease in the uptake of the first dose of the HPV vaccine (HPV1) in Denmark and, importantly, whether some groups of individuals were more susceptible to negative media coverage.

METHODS

We measured HPV vaccine uptake of 12-year-old girls born in 2001 to 2004 using Danish administrative data. A quasi-experimental design was employed to assess whether a documentary that was critical of the HPV vaccine and aired in March 2015 affected HPV uptake.

RESULTS

The documentary led to a quick and substantial decrease in the monthly propensity to vaccinate, which dropped 3 percentage points-or about 50%-in response to the documentary. Responses differed substantially across subgroups, and girls from families with high socioeconomic status (SES) were more susceptible to the negative media coverage.

CONCLUSIONS

Susceptibility to negative media coverage varied substantially across subgroups, highlighting the need for policy makers to appropriately target and differentiate initiatives to improve vaccine compliance rates.

Hospital Records of Pain, Fatigue, or Circulatory Symptoms in Girls Exposed to Human Papillomavirus Vaccination: Cohort, Self-Controlled Case Series, and Population Time Trend Studies

Human papillomavirus (HPV) vaccination has been associated with subsequent diffuse symptoms in girls, reducing public confidence in the vaccine. We examined whether girls have nonspecific outcomes of HPV vaccination, using triangulation from cohort, self-controlled case series (SCCS), and population time trend analyses carried out in Denmark between 2000 and 2014. The study population consisted of 314,017 HPV-vaccinated girls and 314,017 age-matched HPV-unvaccinated girls (cohort analyses); 11,817 girls with hospital records (SCCS analyses); and 1,465,049 girls and boys (population time trend analyses). The main outcome measures were hospital records of pain, fatigue, or circulatory symptoms. The cohort study revealed no increased risk among HPV vaccine-exposed girls, with incidence rate ratios close to 1.0 for abdominal pain, nonspecific pain, headache, hypotension/syncope, tachycardia (including postural orthostatic tachycardia syndrome), and malaise/fatigue (including chronic fatigue syndrome). In the SCCS analyses, we observed no association between HPV vaccination and subsequent symptoms. In time trend analyses, we observed a steady increase in these hospital records in both girls and (HPV-unvaccinated) boys, with no relationship to the 2009 introduction of HPV vaccine to Denmark's vaccination program. This study, which had nationwide coverage, showed no evidence of a causal link between HPV vaccination and diffuse autonomic symptoms leading to hospital contact.

Immunization Campaigns and Strategies against Human Papillomavirus in Italy: The Results of a Survey to Regional and Local Health Units Representatives

Objective. The study aimed to assess the impact of HPV immunization campaigns organizational aspects, the characteristics of immunization program (vaccination targets and type of offer), and communicative strategies adopted by four Italian administrative regions on vaccination coverage observed. Methods. From November 2017 to March 2018, regional and Local Health Units (LHUs) representatives were invited to complete an online survey including 54 questions evaluating vaccination invite systems, access systems to vaccination centres, reminder and recall systems, and adverse events surveillance. An overall descriptive analysis was conducted. Since observed vaccine coverage (VC) obtained in females (2002-2004 birth cohorts) was lower than objectives fixed by the Italian Ministry of Health, variables were assessed using the national VC mean obtained in the 2003 girls birth cohort as outcome. Results. Twenty-six LHUs belonging to 4 Northern and Southern Italian regions participated in the study. Organizational aspects significantly related to VC lower than the national mean were access to vaccine centres without appointment and parents' reservation as appointment planning system. Recall systems for both the first and the second dose, including the appointment in the invitation letter, the availability of regional immunization registry, and education of healthcare workers on universal HPV immunization strategies, instead, were related to higher VC. As regards preadolescent immunization strategies, both VC obtained in girls and boys were far from the Ministerial goals. Only 20% of LHUs introduced multicohort female strategies while all LHUs adopted copayment targeting both men and women. Immunizations strategies targeting subjects at risk were implemented only in half of participating LHUs. Conclusions. VC observed in participating LHUs are largely lower than the national objectives in all anti-HPV vaccine targets. Both organizational and educational strategies have to be implemented to improve the VC goals.

Hospital contacts and diagnoses five years prior to HPV vaccination among females referred for suspected adverse vaccine effects: A Danish nationwide case-control study

BACKGROUND

High health care utilization before Human Papilloma Virus (HPV) vaccination might be associated with increased risk of suspected adverse effects (AE's) after vaccination. We investigated the association between hospital contacts and diagnoses before HPV vaccination and risk of later referral to a specialized hospital setting (HPV center) for suspected AE's.

METHODS

The study was a Danish register-based matched case-control study. Cases were females referred to an HPV center. Five controls per case were randomly selected in the source population of HPV vaccinated females. Information on hospital contacts and diagnoses was obtained from the Danish National Patient Registry. Conditional logistic regression analyses were used to investigate the association between having one or more diagnoses in each specific International Classification of Diseases 10th version (ICD-10) chapter five years before the HPV vaccination and subsequent referral to an HPV center.

RESULTS

We identified 1496 cases and 7480 controls. In total, 80% of the cases versus 65% of the controls had at least one hospital contact prior to HPV vaccination (Prevalence Proportion Ratio - PPR: 1.24 (95% Confidence Interval - CI: 1.21-1.27)), with 24% vs 12% (PPR: 1.97 (95% CI: 1.76-2.19)) having six or more contacts. Cases were more likely to have had a diagnosis in 15 out of 19 ICD-10 chapters before the vaccination, with ORs larger than 1.8 for infectious diseases, psychiatric diseases, diseases of the nervous, circulatory, digestive and musculoskeletal system, unspecific symptoms and unspecific contacts.

CONCLUSION

Pre-vaccination morbidity and health care utilization seem to play a role in the path leading to suspected AE's after HPV vaccination. Since many of the diagnoses that were particularly increased before vaccination in referred females are overlapping with the most frequent symptoms reported, we cannot exclude that for some of the females, the suspected AE's might have been existing already before the vaccination.