Factors associated with delayed infant immunization in a nationally representative cohort study

Association between parental vaccine hesitancy and geographical coverage for childhood vaccination: A cross-sectional study

BACKGROUND

The aim of this study was to explore the relationship between parental vaccine hesitancy and vaccine coverage for all recommended vaccines for children under five years residing in Statistical Areas Level 3 (SA3). SA3 groupings represent clustering groups of smaller areas, such as regional towns and cities or clusters of related suburbs, which share similar regional characteristics, administrative boundaries or labour markets, and generally have populations between 30,000 and 130,000 persons.

METHODS

We used parental vaccine hesitancy data from the VBAT (Vaccine Barrier Assessment Tool) study and vaccine coverage by postcode data from the Australian Immunisation Coverage Report 2020/21. Binary logistic regression analysis explored the association.

RESULTS

There were complete data for 1110 participants. We found lower vaccine concerns in parents residing in medium coverage (adjusted odds ratio (aOR) 0.36, 95 % confidence interval (CI): 0.22 to 0.59) and high coverage (aOR 0.37, 95 % CI: 0.22 to 0.60) SA3 areas compared to low coverage geographical areas.

CONCLUSIONS

Developing effective policies to vaccinate children under five in low coverage areas will help reduce vaccine inequity in Australia. Future strategies to improve vaccine coverage should consider ways to address both access and acceptance barriers.

Spatial distribution and determinants of measles vaccination dropout among under-five children in Ethiopia: A spatial and multilevel analysis of 2019 Ethiopian demographic and health survey

BACKGROUND

Each year, vaccine-preventable diseases cost the lives of 8.8 million under-five children. Although vaccination prevents 1-2 million childhood deaths worldwide, measles vaccination dropouts are not well studied in developing countries, particularly in Ethiopia. Therefore, this study aims to assess the spatial distribution of the measles vaccination dropout and its determinants among under-five children in Ethiopia.

METHODS

Data from Ethiopian Demographic and Health Survey 2019 was used for data analysis. The study used a total of 5,753 children. Spatial autocorrelations was used to determine the spatial dependency of measles vaccination dropout. Ordinary interpolation was employed to forecast measles vaccination dropout. Factors associated with measles vaccination dropout were declared significant at p-values <0.05. The data were interpreted using the confidence interval and adjusted odds ratio. A model with the lowest deviance and highest logliklihood ratio was selected as the best-fit model.

RESULTS

In Ethiopia, one in three under-five children had measles vaccination dropouts. Factors such as birth interval (AOR = 1.87, 95% CI: 1.30, 2.70), unmarried marital status women (AOR = 3.98, 95% CI: 1.08, 8.45), ≤1 number of under-five children (AOR = 3.86, 95% CI: 2.56, 5.81), rural place of residence (AOR = 2.43, 95% CI: 2.29, 3.11), low community-level ANC utilization (AOR = 3.20, 95% CI: 2.53, 3.56), and residing in Benishangul Gumuz (AOR = 1.80, 95% CI: 1.061, 3.06) had higher odds of measles vaccination dropout.

CONCLUSIONS

Measles vaccination dropout rates in Ethiopia among under-five children were high compared to the maximum tolerable vaccination dropout level of 10% by the WHO. Both individual and community-level variables were determinants of measles vaccination dropout. The ministry of health in Ethiopia should give attention to those mothers of under-five children who reported underutilization of ANC services and rural residences while designing policies and strategies in areas of high spatial clustering of vaccine dropout in Ethiopia.

Catch-up immunisation for migrant children in Melbourne: A qualitative study with providers to determine key challenges

BACKGROUND

Current models of immunisation service delivery in Australia are not meeting the needs of migrant children, who experience a higher burden of vaccine preventable disease and lower immunisation rates compared to non-migrant children. Understanding the experiences of immunisation providers is critical for designing effective and tailored interventions to improve this service. This study aimed to identify the facilitators and barriers to providers delivering a comprehensive catch-up immunisation service to migrant children in Melbourne, Australia.

METHODS

Semi-structured interviews with council and general practice immunisation providers were conducted. Recorded interviews were transcribed and coded inductively using thematic analysis. Identified themes were then deductively categorised according to the Capability, Opportunity and Motivation of Behaviour (COM-B) model.

RESULTS

Twenty-four providers (five practice nurses, six general practitioners, six council nurses and seven council administration officers) were interviewed between March and June 2021. Fourteen themes were identified that contributed to the delivery of an effective catch-up immunisation service. Capability themes included training, experience and skills to perform the service and communicate with families. Opportunity themes incorporated time, workplace norms, traits of migrant families, costs, systems and resources. Themes related to motivation were provider responsibility, beliefs about migrant health, and immunisation prioritisation.

CONCLUSIONS

Key barriers for providers to deliver a comprehensive catch-up immunisation service were related to opportunity. Developing an online tool to support catch-up schedule development and reporting, and funding provider time to calculate the schedule are primary actions that could overcome opportunity barriers. Capability and motivation barriers for general practitioners included limited time, skills, and motivation compared to nurses. These barriers may be overcome with improvements to training that focus on upskilling nurses to deliver the catch-up service. Service delivery challenges are multifactorial, requiring a range of strategies to optimise this service and increase immunisation coverage in migrant children.

Linking cohort data and Welsh routine health records to investigate children at risk of delayed primary vaccination

BACKGROUND

Delayed primary vaccination is one of the strongest predictors of subsequent incomplete immunisation. Identifying children at risk of such delay may enable targeting of interventions, thus decreasing vaccine-preventable illness.

OBJECTIVES

To explore socio-demographic factors associated with delayed receipt of the Diphtheria, Tetanus and Pertussis (DTP) vaccine.

METHODS

We included 1,782 children, born between 2000 and 2001, participating in the Millennium Cohort Study (MCS) and resident in Wales, whose parents gave consent for linkage to National Community Child Health Database records at the age seven years contact. We examined child, maternal, family and area characteristics associated with delayed receipt of the first dose of the DTP vaccine.

RESULTS

98.6% received the first dose of DTP. The majority, 79.6% (n = 1,429) received it on time (between 8 and 12 weeks of age), 14.2% (n = 251) received it early (prior to 8 weeks of age) and 4.8% (n = 79) were delayed (after 12 weeks of age); 1.4% (n = 23) never received it. Delayed primary vaccination was more likely among children with older natural siblings (risk ratio 3.82, 95% confidence interval (1.97, 7.38)), children admitted to special/intensive care (3.15, (1.65, 5.99)), those whose birth weight was > 4Kg (2.02, (1.09, 3.73)) and boys (1.53, (1.01, 2.31)). There was a reduced risk of delayed vaccination with increasing maternal age (0.73, (0.53, 1.00) per 5 year increase) and for babies born to graduate mothers (0.27, (0.08, 0.90)).

CONCLUSIONS

Although the majority of infants were vaccinated in a timely manner, identification of infants at increased risk of early or delayed vaccination will enable targeting of interventions to facilitate timely immunisation. This is to our knowledge the first study exploring individual level socio-demographic factors associated with delayed primary vaccination in the UK and demonstrates the benefits of linking cohort data to routinely-collected child health data.

Factors related to parents' adherence to childhood immunization

BACKGROUND

Immunizations protect children from deadly infectious diseases. Yet, there is still insufficient understanding of the factors associated with parents' non-adherence to immunizations in contexts outside of Western countries. The aim of this study is twofold: (a) to investigate non-adherence to immunizations for children aged 6 months to 6 years in Saudi Arabia based on the number of immunizations missing or delayed by more than one month; and (b) to examine the underlying factors that predict the extent of non-adherence based on the Health Belief Model framework.

METHODS

A cross-sectional study was carried out in 22 randomly selected primary health care centers. Structured interviews were also conducted to collect data using the modified Health Belief Model questionnaire. Multiple regression analysis was used to assess the predictors of the extent of non-adherence.

RESULTS

Based on data from 220 participants, 51.8% of parents did not adhere with childhood immunizations. There was no significant relationship between parents' sociodemographic characteristics and the extent of their hesitancy about children's immunizations. The linear combination of perception of infectious disease severity, perception of their children's susceptibility, perception of immunization benefits, perception of fewer barriers to obtaining immunizations, cues to action related to immunizations, and self-efficacy predicted the extent of non-adherence to immunizations (F (11.220) = 2.595, p < 0.001) and explained 12% of its variance. Yet, only perceived children's susceptibility, perceived barriers, and self-efficacy independently predicted parents' non-adherence.

CONCLUSION

Saudi Arabia's high proportion of non-adherence to childhood immunizations should be addressed. For instance, a health education program could be developed to increase parents' awareness that their children are susceptible to health risks. Paying a special attention to existing barriers in accessing and receiving the immunizations is crucial. In addition, building parents' self-efficacy, which is confident in making healthy decisions, such as keeping their children's immunizations up to date, is important.

Adherence to the paediatric immunisation schedule in England

Both adequate coverage and adherence to paediatric immunisation schedules are required for optimal protection against vaccine preventable diseases. We studied the timeliness of routine paediatric vaccinations according to the NHS’s immunisation schedule and potential factors of schedule adherence. Immunisation data was obtained from the Royal College of General Practitioners (RCGP) Research and Surveillance Centre (RSC). We collected vaccine types, doses, and dates for all routine paediatric vaccines between 2008 and 2018: DTaP/IPV/Hib/HepB, DTaP/IPV/Hib, DTaP/IPV, dTaP/IPV, Td/IPV, MMR, PCV, MenB, MenC, MenACWY, Hib/MenC, RV, HPV. Adherence to the immunisation schedule was calculated for each vaccine and dose. Differences in adherence between genders, NHS regions, and IMD quintiles were analysed. Our study included 6′257′828 vaccinations in 1′005′827 children. Seventy-five percent of first doses were administered within one (for vaccines scheduled in the first year of life) or two months (for vaccines scheduled later in life) following the recommended age, 19% too late and 6% too early. About half of the subsequent doses were given timely. The time between first and second doses was too short for 36% of vaccinations while 13% of second doses were administered too long after the first dose. Third doses were administered timely for 45%, too short for 37%, and too long for 18% of vaccinations. Differences in immunisation schedule adherence between girls and boys were negligible, except for HPV, and differences between the four main NHS regions were small. Overall, immunisation schedule adherence improved slightly with decreasing deprivation according to the Index of Multiple Deprivation. Efforts are required to improve the timeliness of paediatric vaccinations and to assure adequate protection against vaccine preventable diseases. We propose developing a compound measure combining coverage and adherence to provide a better indication of the protection against vaccine preventable diseases in a community.

Immunisation Coverage Annual Report 2019

Australian Immunisation Register data have been analysed for children aged < 5 years, focusing on changes in vaccination coverage at standard age milestones (12, 24 and 60 months) between 2018 and 2019. ‘Fully vaccinated’ coverage in 2019 increased by 0.1–0.4% at the three age milestones to 94.3% at 12 months, 90.2% at 24 months (in the context of additional antigens required at 24 months) and 94.2% at 60 months. Rotavirus vaccine coverage (2 doses) increased from 90.9% in 2018 to 91.9% in 2019. ‘Fully vaccinated’ coverage in Aboriginal and Torres Strait Islander (hereafter respectfully referred to as Indigenous) children increased by 0.5–1.1% in 2019, reaching 92.9% at 12 months, 88.9% at 24 months and 96.9% at the 60 months (2.7 percentage points higher than in children overall). Recorded influenza vaccination coverage in children aged 6 months to < 5 years increased by 11.4 percentage points to 42.7% in Indigenous children in 2019, and by 15.6 percentage points to 41.8% in children overall. Longstanding issues with timeliness of vaccination in Indigenous children persisted, although the disparity between Indigenous and non-Indigenous children in on-time coverage (within 30 days of due date), for vaccines due at 4 months of age, decreased from 10.4–10.7 to 9.6–9.8 percentage points between 2018 and 2019. The timeliness of ‘fully vaccinated’ coverage was also examined at earlier age milestones (3 months after due date of last scheduled vaccine) of 9, 15, 21 and 51 months, by Indigenous status, socioeconomic status and remoteness of area of residence. Coverage in children living in the least-advantaged residential area quintile was 2.6–2.7% lower than that for those living in the most-advantaged quintile at the 9-, 15- and 21-month milestones, although these disparities were 0.5–1.5 percentage points lower than in 2018. Coverage at the earlier milestones in Indigenous children in remote areas was 1.5–6.7% percentage points lower than that for Indigenous children in major cities and regional areas, although there were some improvements since 2018. Importantly, although Indigenous children had lower coverage for the second dose of measles-mumps-rubella vaccine at 24 months (92.7% versus 93.3% overall), coverage increased to 98.8% at 60 months; coverage was also high overall at 96.4%, above the 95% target critical to measles control. In conclusion, this report demonstrates continuing improvements across a range of immunisation indicators in Australia in 2019. However, some issues with timeliness persist, particularly in Indigenous and socioeconomically disadvantaged children. New coverage targets for earlier protection in the first 2 years of life may be indicated, along with a review of current ‘fully vaccinated’ assessment algorithms, particularly at the 60-month age milestone.

Immunisation Coverage Annual Report 2018

Abstract

Australian Immunisation Register data have been analysed for children aged < 5 years, focusing on changes in coverage at key milestone ages (12, 24 and 60 months) between 2017 and 2018, while also documenting longer term trends. Fully vaccinated coverage increased at the 12- and 60-months milestones to 93.9% and 94.0%, respectively, but, in the context of additional antigens required, decreased to 90.1% at 24 months. Following the move to a two-dose rotavirus vaccine schedule across Australia from mid-2017, rotavirus vaccine coverage increased from 86.8% to 90.9%. In 2018, most jurisdictions funded influenza vaccine for non-Indigenous children aged 6 months to < 5 years; the National Immunisation Program has funded influenza vaccine for Aboriginal and Torres Strait Islander children and medically at-risk children since 2015 and 2010, respectively. Recorded influenza vaccine coverage in Aboriginal and Torres Strait Islander children doubled from 14.9% to 31.4%, and increased fivefold in non-Indigenous children from 5.0% to 25.9% in 2018. The timeliness of fully vaccinated coverage was also examined at earlier milestones (3 months after due date of last scheduled vaccine) of 9, 15, 21 and 51 months, by area of residence. For all children, coverage among those living in the least advantaged residential area quintile was 3-4% lower than that for those in the most advantaged quintile at the 9-, 15- and 21-month milestones. Importantly, although Aboriginal and Torres Strait Islander children had lower coverage for the second dose of measles-mumps-rubella vaccine at 24 months (91.8% versus 93.1% for non-Indigenous), coverage increased to 98.5% at 60 months; coverage was also high in non-Indigenous children at 96.2%, above the 95% target critical to measles control. These data demonstrate continuing improvements in immunisation coverage and suggest potential new coverage targets for earlier protection in the first two years of life.

Immunisation Coverage Annual Report 2019

Abstract

Australian Immunisation Register data have been analysed for children aged < 5 years, focusing on changes in vaccination coverage at standard age milestones (12, 24 and 60 months) between 2018 and 2019. 'Fully vaccinated' coverage in 2019 increased by 0.1-0.4% at the three age milestones to 94.3% at 12 months, 90.2% at 24 months (in the context of additional antigens required at 24 months) and 94.2% at 60 months. Rotavirus vaccine coverage (2 doses) increased from 90.9% in 2018 to 91.9% in 2019. 'Fully vaccinated' coverage in Aboriginal and Torres Strait Islander (hereafter respectfully referred to as Indigenous) children increased by 0.5-1.1% in 2019, reaching 92.9% at 12 months, 88.9% at 24 months and 96.9% at the 60 months (2.7 percentage points higher than in children overall). Recorded influenza vaccination coverage in children aged 6 months to < 5 years increased by 11.4 percentage points to 42.7% in Indigenous children in 2019, and by 15.6 percentage points to 41.8% in children overall. Longstanding issues with timeliness of vaccination in Indigenous children persisted, although the disparity between Indigenous and non-Indigenous children in on-time coverage (within 30 days of due date), for vaccines due at 4 months of age, decreased from 10.4-10.7 to 9.6-9.8 percentage points between 2018 and 2019. The timeliness of 'fully vaccinated' coverage was also examined at earlier age milestones (3 months after due date of last scheduled vaccine) of 9, 15, 21 and 51 months, by Indigenous status, socioeconomic status and remoteness of area of residence. Coverage in children living in the least-advantaged residential area quintile was 2.6-2.7% lower than that for those living in the most-advantaged quintile at the 9-, 15- and 21-month milestones, although these disparities were 0.5-1.5 percentage points lower than in 2018. Coverage at the earlier milestones in Indigenous children in remote areas was 1.5-6.7% percentage points lower than that for Indigenous children in major cities and regional areas, although there were some improvements since 2018. Importantly, although Indigenous children had lower coverage for the second dose of measles-mumps-rubella vaccine at 24 months (92.7% versus 93.3% overall), coverage increased to 98.8% at 60 months; coverage was also high overall at 96.4%, above the 95% target critical to measles control. In conclusion, this report demonstrates continuing improvements across a range of immunisation indicators in Australia in 2019. However, some issues with timeliness persist, particularly in Indigenous and socioeconomically disadvantaged children. New coverage targets for earlier protection in the first 2 years of life may be indicated, along with a review of current 'fully vaccinated' assessment algorithms, particularly at the 60-month age milestone.

Immunisation Coverage Annual Report 2018

Abstract

Australian Immunisation Register data have been analysed for children aged < 5 years, focusing on changes in coverage at key milestone ages (12, 24 and 60 months) between 2017 and 2018, while also documenting longer term trends. Fully vaccinated coverage increased at the 12- and 60-months milestones to 93.9% and 94.0%, respectively, but, in the context of additional antigens required, decreased to 90.1% at 24 months. Following the move to a two-dose rotavirus vaccine schedule across Australia from mid-2017, rotavirus vaccine coverage increased from 86.8% to 90.9%. In 2018, most jurisdictions funded influenza vaccine for non-Indigenous children aged 6 months to < 5 years; the National Immunisation Program has funded influenza vaccine for Aboriginal and Torres Strait Islander children and medically at-risk children since 2015 and 2010, respectively. Recorded influenza vaccine coverage in Aboriginal and Torres Strait Islander children doubled from 14.9% to 31.4%, and increased fivefold in non-Indigenous children from 5.0% to 25.9% in 2018. The timeliness of fully vaccinated coverage was also examined at earlier milestones (3 months after due date of last scheduled vaccine) of 9, 15, 21 and 51 months, by area of residence. For all children, coverage among those living in the least advantaged residential area quintile was 3-4% lower than that for those in the most advantaged quintile at the 9-, 15- and 21-month milestones. Importantly, although Aboriginal and Torres Strait Islander children had lower coverage for the second dose of measles-mumps-rubella vaccine at 24 months (91.8% versus 93.1% for non-Indigenous), coverage increased to 98.5% at 60 months; coverage was also high in non-Indigenous children at 96.2%, above the 95% target critical to measles control. These data demonstrate continuing improvements in immunisation coverage and suggest potential new coverage targets for earlier protection in the first two years of life.

Control of vaccine preventable diseases in Australian infants: reviewing a decade of experience with DTPa-HBV-IPV/Hib vaccine

The combined vaccine against diphtheria, tetanus, pertussis, hepatitis B, poliomyelitis, and Haemophilus influenzae b (DTPa-HBV-IPV/Hib, Infanrix Hexa, GSK) has been used for childhood immunization in Australia according to a two-, four-, six-month schedule since 2009. We reviewed data available in the Australian National Notifiable Diseases Surveillance System, annual vaccination coverage reports, the Database of Adverse Event Notifications, and peer-reviewed literature to assess vaccine coverage rates, incidence of all six vaccine preventable diseases, and the safety profile of DTPa-HBV-IPV/Hib vaccine in Australian infants over a period of ten years of exclusive use. Between 2009 and 2018 vaccine coverage for infants aged 12 months increased from 91.7% to 94.0% and from 84.9% to 92.6% for all and for Indigenous infants, respectively. Over the same time period, there were no reports of poliomyelitis, diphtheria or tetanus in infants <12 months of age. The incidence of hepatitis B among Australian infants <12 months of age remains 10 to 20-fold lower than the national average. Control of Haemophilus influenzae b (Hib) and pertussis disease has continued to be challenging. Timely administration of the primary series, as well as increasing coverage rates, particularly among Indigenous children, has contributed to improvements in Hib and pertussis disease control. The incorporation of additional strategies such as adjustment of the first vaccination encounter to six weeks of age, parental cocooning, and most recently maternal vaccination has further reduced the burden of pertussis, particularly during the first six months of life. The frequency of the ten most common adverse events related to the DTPa-HBV-IPV/Hib vaccine demonstrates an acceptable safety profile. Data collected over ten years of consistent, exclusive use of the DTPa-HBV-IPV/Hib vaccine in Australia highlights combination vaccination as a cornerstone in maintaining infant health.

Predictors of immunization coverage among 12-23 month old children in Ethiopia: systematic review and meta-analysis

BACKGROUND

Immunization is one of modern medicine's greatest achievements in the last three decades. Annually it can prevent nearly 2 to 3 million deaths. Understanding the determinants of effective immunization coverage is a critical undertaking. Accordingly, we set out to check the best available evidence of outstanding predictors of immunization coverage among children aged 12-23 months in Ethiopia.

METHOD

Electronic databases including PubMed, Google Scholar, HINARI, and SCOPUS, Web of Science, African Journals Online, Ethiopian Medical Journals were searched. The search process, study selection, critical appraisal, and data extraction were done independently by two reviewers using Joanna Briggs Institute Meta-analysis for Review Instrument (JBI-MAStARI). The difference between reviewers was resolved with a third person. The risk of bias was assessed by the Newcastle Ottawa Tool for observational studies. Data were extracted using the Microsoft Excel checklist and exported to STATA 13. Heterogeneity was assessed using I2, Funnel plot and Egger's test was used to check for publication bias.

RESULTS

We identified 26 studies with 15,042 children with mothers/caretakers to assess factors associated with immunization coverage and significant factors were: maternal formal education, (OR = 2.45; 95% CI: 1.62-3.72), paternal formal education, (OR = 1.01; 95% CI: 0.27-3.77), residence, (OR = 2.11; 95% CI: 1.00-4.45), birth at health facility (OR = 1.86; 95% CI: 0.99-3.49), family size less than four, (OR = 1.81; 95% CI: 1.16-2.84), knowledge on age of immunization to be completed (OR = 6.18;95% CI: 3.07-12.43), knowledge on immunization schedule (OR = 2.49; 95% CI: 1.35-4.59), time to travel to health faculties, (OR = 1.74; 95% CI: 0.62-4.89), antennal care, (OR = 3.11; 95% CI: 1.64-5.88), and tetanus toxoid vaccination, (OR = 4.82; 95% CI: 2.99-7.75).

CONCLUSION

Our findings showed that literacy, residence, awareness, family size, maternal health services use, and proximity of the health facilities were factors associated with full immunization. This implies that there is a need for primary health service expansion and health education to "hard to reach areas" to improve immunization coverage for children aged 12-23 months.

Vaccine sentiments and under-vaccination: Attitudes and behaviour around Measles, Mumps, and Rubella vaccine (MMR) in an Australian cohort

OBJECTIVE

The study aimed to examine the consistency in factors associated with attitudes towards vaccination and MMR vaccination status.

METHODS

Using the nationally representative Longitudinal Study of Australian Children matched with the Australian Childhood Immunisation Register, 4,779 children were included from 2004-2005 to 2010-11. Different MMR vaccine dosages and general attitude towards vaccination were modelled individually with multinomial logit regressions, controlling for demographic, socioeconomic, and health related factors of the children and their primary carers.

RESULTS

The group with non-vaccination and negative attitudes was characterised by more siblings and older parents the group with under-vaccination but positive attitudes was characterised by younger parental age; and the group with under-vaccination and neutral attitudes was characterised by less socioeconomically advantaged areas. The presence of parental medical condition(s), being private or public renters, and higher parental education were associated with under-vaccination but not with attitudes towards vaccination, whilst parental religion was associated with attitudes towards vaccination but not reflected in the vaccine uptake.

CONCLUSIONS

Vaccine attitudes were largely consistent with MRR vaccine outcomes. However, there was variation in the associations of factors with vaccine attitudes and uptake. The results have implications for different policy designs that target subgroups with consistent or inconsistent vaccination attitudes and behaviour. Parents with intentional and unintentional under-vaccination are of policy concern and require different policy solutions.

A clinical update on vaccines: focus on determinants of under-immunization and special considerations for adolescents

PURPOSE OF REVIEW

The current article reviews recent literature related to pediatric and adolescent vaccination, specifically focusing on social determinants of under-immunization, expanding adolescent immunization rates, and new recommendations surrounding the meningococcal serotype B vaccine (MenB).

RECENT FINDINGS

Vaccine refusals and vaccine-preventable diseases have been rising in some parts of the world, and appear to be linked to household factors, such as a family's socioeconomic status. Adolescents have lower immunization rates than younger children. Newer vaccines targeted at adolescents, such as the MenB vaccine, have yet to be widely accepted by pediatric providers, parents, and patients.

SUMMARY

Pediatric healthcare providers should attempt to increase local immunization rates by vaccinating children at all eligible office visits and utilizing electronic health record decision-support tools. Although the number of families who choose not to vaccinate their children may be rising, providers can be innovative (e.g. incorporate digital vaccine reminder systems) and increase their familiarity with new vaccine recommendations to continue to prevent serious vaccine-preventable diseases.

Infant, maternal and demographic predictors of delayed vaccination: A population-based cohort study

BACKGROUND

Receiving vaccines at or close to their due date (vaccination timeliness) is a now key measure of program performance. However, studies comprehensively examining predictors of delayed infant vaccination are lacking. We aimed to identify predictors of short and longer-term delays in diphtheria-tetanus-pertussis (DTP) vaccination by dose number and ethnicity.

METHODS

Perinatal, notification, death and immunisation databases were linked for 1.3 million births in 2000-11 from two Australian states (Western Australia and New South Wales), with follow-up data until 2013. Ordinal logistic regression was used to estimate adjusted relative risks (RR) by degree of delay. Separate models were constructed for each vaccine dose and for Aboriginal and non-Aboriginal children.

RESULTS

Each dose-specific cohort included at least 49,000 Aboriginal and 1.1 million non-Aboriginal children. Delayed receipt was more common among Aboriginal than non-Aboriginal children (eg for the first dose of DTP [DTP1] 19.4 v 8.1%). Risk factors for delayed vaccination were strongest for DTP1, and delayed receipt of DTP1 was a key driver of subsequent delays; every week DTP1 was delayed was associated with a 1.6 to 2-fold increased risk of delayed DTP2 receipt. For DTP1, ≥3 previous pregnancies (the only factor more strongly associated with longer than shorter delays; RR ≥5 compared to no previous pregnancies), and children born to mothers <20 years of age (RR ≥2 compared to ≥35 years) were at highest risk of delay. Other independent predictors were prematurity, maternal smoking during pregnancy, and being born in Western Australia (if Aboriginal) or another country in the Oceania region.

CONCLUSION

The sub-populations at risk for delayed vaccination we have identified are likely generalisable to other high-income settings. Measures to improve their dose 1 timeliness, particularly for children with older siblings, are likely to have significant flow-on benefits for timeliness of later doses.

Identification of the determinants of incomplete vaccination in Australian children

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Demographic/social factors, vaccine beliefs, and vaccination status were captured.

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Most parents are supportive of vaccination.

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Many parents incorrectly reported their child as fully vaccinated.

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Incomplete vaccination was associated with demographic and socio-economic factors.

Background and aims

We aimed to understand the risk factors associated with incomplete vaccination, which may help to identify and prioritise opportunities to intervene.

Methods

Consenting parents of children <6 years old attending an outpatient clinic completed a questionnaire, which captured demographic information and their level of agreement with belief statements about vaccination using a 7-point Likert scale. Vaccination status was determined from the Australian Childhood Immunisation Register and deemed either “complete” (no doses overdue) or “incomplete” (1 or more doses overdue) at the time of questionnaire completion.

Results

Of 589 children of respondents, 116 (20%) had an incomplete vaccination status. Of these, nearly two-thirds (63%) of parents believed that their child was, in fact, fully-vaccinated. Compared to those with a complete vaccine status, children with an incomplete vaccine status were more likely to be born overseas (p < 0.001), have a larger family size (p = 0.02) and to have parents with lower educational attainment (p = 0.001). Parents of children with an incomplete status reported more doubt about the importance of vaccination and greater concern about vaccine safety, compared to parents of children with a complete status.

Conclusion

Most parents are supportive of vaccination. Sociodemographic factors may contribute more to the risk of incomplete vaccination than attitudes or beliefs. Some parents are unaware of their child’s vaccination status, suggesting that simple and modern reminders may assist parents to keep up to date.

Inequalities in childhood vaccination timing and completion in London

The UK primary vaccination course includes vaccination against diphtheria, tetanus, pertussis, polio and Haemophilus influenzae type b (DTaP/IPV/Hib) and is scheduled at ages four, 8 and 12 weeks, followed by a 'preschool booster' at age three years four months. Vaccine coverage is generally measured at age one, two and five years. In addition to high coverage, vaccination should be timely to maximise population protection. Vaccination histories for 315,381 children born March 2001 to April 2010 were extracted from Child Health Information Systems in nine London health service areas and grouped into first and fifth birthday cohorts. We assessed timeliness of receipt of DTaP/IPV/Hib and drop-out rates by ethnicity, deprivation and area. Most children received their first, second and third doses on time at two, three, and four months. Among children completing by one year and after adjusting for deprivation and health area, compared with White-British children, Somali and Bangladeshi children were less likely to have received three doses of DTaP/IPV/Hib by six months of age (-11% and -5% respectively). Differences in timeliness by deprivation and health area existed, but were smaller. Compared with White-British children, children of Polish, Somali and Caribbean ethnicities were less likely to return for preschool booster, with a drop-out rate at least 7% higher in these groups. Within the fifth birthday cohort, only 2.3% of children who were completely unvaccinated (575/25,095) at age one year were fully vaccinated by age five. Higher proportions of partially vaccinated (one or two doses) children at age one year went on to be fully vaccinated by age five ((836/3213) 26.0% and (3565/6076) 58.7% respectively). These inequalities suggest that tailored approaches may be required to target specific groups with regards to improving vaccine uptake.