Measuring the timeliness of childhood vaccinations: Using cohort data and routine health records to evaluate quality of immunisation services

Impact of pregnancy vaccine uptake and socio-demographic determinants on subsequent childhood Measles, Mumps and Rubella vaccine uptake: A UK birth cohort study

BACKGROUND

We examined the association between socio-demographic determinants and uptake of childhood Measles, Mumps & Rubella (MMR) vaccines and the association between pregnant women's pertussis vaccine uptake and their children's MMR vaccine uptake.

METHODS

We used nationally-representative linked mother-baby electronic records from the United Kingdom's Clinical-Practice-Research-Datalink. We created a birth cohort of children born between 01.01.2000 and 12.12.2020. We estimated the proportion vaccinated with first MMR vaccine by age 2 years and first and second MMR vaccines by age 5 years. We used survival-analysis and Cox proportional hazard models to examine the association between deprivation, ethnicity and maternal age and pertussis vaccination in pregnancy and children's MMR uptake.

RESULTS

Overall, 89.4 % (710,797/795,497) of children had first MMR by age 2 years and 92.6 % (736,495/795,497) by age 5 years. Among children still in the cohort when second MMR was due, 85.9 % (478,480/557,050) had two MMRs by age 5 years. Children from the most-deprived areas, children of Black ethnicity and children of mothers aged < 20 years had increased risk of being unvaccinated compared with children from the least-deprived areas, White children and children of mothers aged 31-40 years: first MMR by 5 years, adjusted Hazard Ratios (HR):0.86 (CI:0.85-0.87), HR:0.87 (CI:0.85-0.88) & HR:0.89 (CI:0.88-0.90) respectively. Deprivation was the determinant associated with the greatest risk of missed second MMR: adjusted HR:0.82 (CI:0.81-0.83). Children of mothers vaccinated in pregnancy were more likely than children of unvaccinated mothers to have MMR vaccines after adjusting for ethnicity, deprivation, and maternal age (First and Second MMRs adjusted HRs:1.43 (CI:1.41-1.45), 1.49 (CI:1.45-1.53).

CONCLUSION

Children from most-deprived areas are less likely to have MMR vaccines compared with children from least-deprived areas. Mothers who take up pregnancy vaccines are more likely to have their children vaccinated with MMR. Healthcare services should promote and facilitate access to both maternal and childhood vaccines during pregnancy.

Mapping the timeliness of routine childhood vaccination in The Gambia: A spatial modelling study

INTRODUCTION

Timeliness of routine vaccination shapes childhood infection risk and thus is an important public health metric. Estimates of indicators of the timeliness of vaccination are usually produced at the national or regional level, which may conceal epidemiologically relevant local heterogeneities and makeitdifficultto identify pockets of vulnerabilities that could benefit from targeted interventions. Here, we demonstrate the utility of geospatial modelling techniques in generating high-resolution maps of the prevalence of delayed childhood vaccination in The Gambia. To guide local immunisation policy and prioritize key interventions, we also identified the districts with a combination of high estimated prevalence and a significant population of affected infants.

METHODS

We used the birth dose of the hepatitis-B vaccine (HepB0), third-dose of the pentavalent vaccine (PENTA3), and the first dose of measles-containing vaccine (MCV1) as examples to map delayed vaccination nationally at a resolution of 1 × 1-km2 pixel. We utilized cluster-level childhood vaccination data from The Gambia 2019-20 Demographic and Health Survey. We adopted a fully Bayesian geostatistical model incorporating publicly available geospatial covariates to aid predictive accuracy. The model was implemented using the integrated nested Laplace approximation-stochastic partial differential equation (INLA-SPDE) approach.

RESULTS

We found significant subnational heterogeneity in delayed HepB0, PENTA3 and MCV1 vaccinations. Specificdistricts in the central and eastern regions of The Gambia consistentlyexhibited the highest prevalence of delayed vaccination, while the coastal districts showed alower prevalence forallthree vaccines. We also found that districts in the eastern, central, as well as in coastal parts of The Gambia had a combination of high estimated prevalence of delayed HepB0, PENTA3 and MCV1 and a significant population of affected infants.

CONCLUSIONS

Our approach provides decision-makers with a valuable tool to better understand local patterns of untimely childhood vaccination and identify districts where strengthening vaccine delivery systems could have the greatest impact.

Timeliness of childhood vaccination in England: A population-based cohort study

INTRODUCTION

Vaccine surveillance for children in England focuses on coverage at ages 1, 2, and 5 years. Previous studies exploring vaccine timeliness have used different arbitrary categories to define whether vaccines were received 'late' or 'on time'. This paper aims to provide more detailed and holistic information on timing and patterns of vaccine uptake across the childhood immunisation schedule in England.

METHODS

We included all children born in England between 2006 and 2014 and registered in the Clinical Practice Research Datalink (CPRD) Aurum, a primary care electronic health record. We described vaccine uptake for representative antigens (pertussis, pneumococcus, measles) by age in days and stratified by ethnicity, region and birth cohort. Alluvial diagrams were used to illustrate common journeys through the vaccination schedule, and we applied survival analysis using accelerated failure time models (AFT) to predict age of vaccine receipt based on timing of previous doses.

RESULTS

573,015 children were followed up until their fifth birthday, when they had 90.16 % coverage for two doses of measles, mumps, rubella (MMR) vaccine and 88.78% coverage for four doses of diphtheria, tetanus, pertussis (DTP) vaccine. Overall, the later the age at which a vaccine was due, the more delay in vaccination. Children of Black Ethnicity or from London showed deviating uptake patterns. If a child received their third DTP dose more than a year later than recommended, they would receive the next dose 2.7 times later than a child who was vaccinated on time. A smaller delay was found for children who did not receive first MMR dose on time.

DISCUSSION

We showed that the risk of vaccination delay increased with the age of the child and significant delay of previous doses. Primary care data can help to promptly identify children at higher risk of delayed vaccination.

Immunisation status of children receiving care and support in Wales: a national data linkage study

Background

In the UK, a robust childhood immunisation programme ensures children are offered protection against serious infections; identifying inequalities in vaccination coverage is essential. This is one of the first data linkage studies to examine coverage of primary, as well as pre-school booster and second dose of MMR vaccines, in children receiving support from social care services across Wales.

Methods

By accessing records held within the Secure Anonymised Information Linkage (SAIL) Databank, vaccination status of children receiving social care and support between April 2016 and March 2021 (n = 24,540) was ascertained. This was achieved through linkage of the Children Receiving Care and Support (CRCS) Census and National Community Child Health Database which holds vaccination records for all children in Wales registered for NHS care. This sample was split into three groups - those children who had never been recorded on the Child Protection Register (CPR) or as 'Looked After' but in CRCS (n = 12,480), children ever on the CPR (n = 6,225) and those ever recorded as 'Looked After' but who were never on the CPR (n = 5,840). The comparison group of children and young people (CYP) never receiving welfare support consisted of 624,905 children.

Results

Children receiving care or support were more likely to be up-to-date with all six vaccines (no recorded vaccines: 0.6-6.3%) compared to children in the comparison group (no recorded vaccines: 3-10.3%). However, of those who were vaccinated, they were less likely to be vaccinated in a timely manner; both early (5.2% vs. 22.2%; margin of error [ME] = 0.52, 95% CI [confidence interval] = -0.18 - -0.17, p < 0.001) and delayed vaccinations were more common (62.7% vs. 71.3%; ME = 0.58, 95% CI = 0.08-0.09, p < 0.001). Validation of the CRCS immunisation flag showed moderate levels of accuracy. Around 70% of immunisation flags were correct across all three groups.

Discussion

Findings suggest a positive association between receiving services under a care and support plan and being up-to-date with immunisations; children receiving support under a care and support plan were more likely to have experienced early or late vaccinations, demonstrating that there is still more inter-disciplinary co-ordination and planning needed to improve these outcomes. Thus, identifying inequalities in vaccination coverage is essential to target interventions and to prioritise geographic areas for catch-up.

Timeliness of routine childhood vaccination among 12-35 months old children in The Gambia: Analysis of national immunisation survey data, 2019-2020

The Gambia's routine childhood vaccination programme is highly successful, however, many vaccinations are delayed, with potential implications for disease outbreaks. We adopted a multi-dimensional approach to determine the timeliness of vaccination (i.e., timely, early, delayed, and untimely interval vaccination). We utilised data for 3,248 children from The Gambia 2019-2020 Demographic and Health Survey. Nine tracer vaccines administered at birth and at two, three, four, and nine months of life were included. Timeliness was defined according to the recommended national vaccination windows and reported as both categorical and continuous variables. Routine coverage was high (above 90%), but also a high rate of untimely vaccination. First-dose pentavalent vaccine (PENTA1) and oral polio vaccine (OPV1) had the highest timely coverage that ranged from 71.8% (95% CI = 68.7-74.8%) to 74.4% (95% CI = 71.7-77.1%). Delayed vaccination was the commonest dimension of untimely vaccination and ranged from 17.5% (95% CI = 14.5-20.4%) to 91.1% (95% CI = 88.9-93.4%), with median delays ranging from 11 days (IQR = 5, 19.5 days) to 28 days (IQR = 11, 57 days) across all vaccines. The birth-dose of Hepatitis B vaccine had the highest delay and this was more common in the 24-35 months age group (91.1% [95% CI = 88.9-93.4%], median delays = 17 days [IQR = 10, 28 days]) compared to the 12-23 months age-group (84.9% [95% CI = 81.9-87.9%], median delays = 16 days [IQR = 9, 26 days]). Early vaccination was the least common and ranged from 4.9% (95% CI = 3.2-6.7%) to 10.7% (95% CI = 8.3-13.1%) for all vaccines. The Gambia's childhood immunization system requires urgent implementation of effective strategies to reduce untimely vaccination in order to optimize its quality, even though it already has impressive coverage rates.

Trends of infant vaccination timeliness and completion in selected urban slum communities in Ibadan, Southwestern Nigeria: A four-year review

BACKGROUND

Suboptimal infant vaccination is common in Nigeria and multiple interventions have been deployed to address the situation. Child health indicators are reported to be worse in urban slums compared with other urban areas, but urban data are usually not disaggregated to show these disparities. Examining the timeliness and completion of infant vaccination in urban slums is important to determine the effectiveness of existing interventions in improving infant vaccination among this vulnerable population. This study explored the trends of infant vaccination in selected urban slum communities in Ibadan, Southwest Nigeria between November 2014 and October 2018.

METHODS

This was a cross sectional study where infant vaccination data were extracted from the immunization clinic records of six primary health care centers that were providing infant vaccination services for seven urban slum communities. Data was analyzed using descriptive statistics and Chi square test at α = 05.

RESULTS

A total of 5,934 infants vaccination records were reviewed, 2,895 (48.8%) were for female infants and 3,002(50.6%) were from Muslim families. Overall, only 0.6% infants had both timely and complete vaccination during the four years under study. The highest number of infants with timely and complete vaccination were seen in 2015(12.2%) and least in 2018(2.9%). Regarding timeliness of the vaccines, BCG, was the least timely among the vaccines given at birth and the pentavalent and oral polio vaccines' timeliness reduced as the age of the infants increased. Both yellow fever and measles vaccines were timelier than the pentavalent vaccines. Vaccines were most timely in 2016(31.3%) and least timely in 2018(12.1%). Those from Muslim families significantly had delayed and incomplete vaccinations compared with those from Chrisitan families (p = 0.026).

CONCLUSION

Infant vaccinations were significantly delayed and incomplete in the study communities during the years reviewed. More focused interventions are required to ensure optimal vaccination of the infants.

Improving the timeliness and completeness of childhood vaccination through color-coded bracelets: a pilot study among Fulani tribe populations in Nigeria

Background

Childhood immunization remains one of the most cost-effective public health interventions. Globally, millions of children are not being reached with safe and effective vaccines and Nigeria has the highest number of unprotected children.

Objective

The effects of locally adapted interventions on vaccination timeliness and completeness were studied amongst Fulani populations across 6 health facilities in 2 districts of Bauchi State, Nigeria.

Methods

The intervention group consisted of newborns who received 5-color-coded bracelets representing different immunization contacts, while the control group had no bracelets. Vaccination rates across contacts were followed for 11 months. In addition, mothers of children in the intervention group were voluntarily recruited as peer-to-peer mobilizers (PPM).

Results

In this study, 435 children were studied. Vaccination completeness was higher in the intervention group compared to the control group at all contacts during follow-up. The difference was most noticeable at the fifth contact, with 158/256 (62%) children in the intervention group completing, compared to 73/179 (41%) in the control group (P<0.0001). Vaccination timeliness was better in the intervention group compared to the control one, which reached statistical significance at the second and third vaccination contacts (P<0.05). 68% of women volunteered as PPM and recruited 82 additional children for vaccination.

Conclusion

This study demonstrated the feasibility of a composite intervention (bracelets and PPM) to increase the completeness and timeliness of childhood immunization and provided preliminary evidence for its efficacy among Fulani populations in Nigeria. Findings from this pilot study should be confirmed through a larger cluster randomized controlled trial.

Implementation of a quality improvement programme using the Active Patient Link call and recall system to improve timeliness and equity of childhood vaccinations: protocol for a mixed-methods evaluation

INTRODUCTION

Call and recall systems provide actionable intelligence to improve equity and timeliness of childhood vaccinations, which have been disrupted during the COVID-19 pandemic. We will evaluate the effectiveness, fidelity and sustainability of a data-enabled quality improvement programme delivered in primary care using an Active Patient Link Immunisation (APL-Imms) call and recall system to improve timeliness and equity of uptake in a multiethnic disadvantaged urban population. We will use qualitative methods to evaluate programme delivery, focusing on uptake and use, implementation barriers and service improvements for clinical and non-clinical primary care staff, its fidelity and sustainability.

METHODS AND ANALYSIS

This is a mixed-methods observational study in 284 general practices in north east London (NEL). The target population will be preschool-aged children eligible to receive diphtheria, tetanus and pertussis (DTaP) or measles, mumps and rubella (MMR) vaccinations and registered with an NEL general practice. The intervention comprises an in-practice call and recall tool, facilitation and training, and financial incentives. The quantitative evaluation will include interrupted time Series analyses and Slope Index of Inequality. The primary outcomes will be the proportion of children receiving at least one dose of a DTaP-containing or MMR vaccination defined, respectively, as administered between age 6 weeks and 6 months or between 12 and 18 months of age. The qualitative evaluation will involve a 'Think Aloud' method and semistructured interviews of stakeholders to assess impact, fidelity and sustainability of the APL-Imms tool, and fidelity of the implementation by facilitators.

ETHICS AND DISSEMINATION

The research team has been granted permission from data controllers in participating practices to use deidentified data for audit purposes. As findings will be specific to the local context, research ethics approval is not required. Results will be disseminated in a peer-reviewed journal and to stakeholders, including parents, health providers and commissioners.

Delayed vaccination the children up to 2 years of age

OBJECTIVE

To analyze factors associated with vaccination delay in children up to 2 years of age.

METHODS

Cross-sectional study with primary data from a probabilistic sample of 388 children born in 2015. The data were described using absolute and relative frequencies. For the analysis of factors associated with vaccination delay, Cox proportional risk regression was performed, considering the time from birth to the first vaccination delay as a dependent variable and as sociodemographic, economic, behavioral aspects related to health services as independent variables.

RESULTS

The delayed vaccination rate was 88.66%. Variables associated with delayed vaccination were: mother's health problems during delivery or in the first 7 days (HR: 0.68; 95% CI: 0.48-0.96); hospitalization of the child in the first 2 years of life (HR: 1.52; 95% CI: 1.10-2.11); mother's poor bond with health professionals at the health unit (HR: 1.75; 95% CI: 1.01-3.03); purposeful decision to delay or not to vaccinate the child (HR: 1.56; 95% CI: 1.14-2.13).

CONCLUSIONS

The factors associated with health care, such as the mother's health problems, the child's hospitalization in the first 2 years of life, and the bond between the mother and the health professionals affect the timeliness of vaccine doses.

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.

Timeliness of routine childhood vaccination in 103 low-and middle-income countries, 1978-2021: A scoping review to map measurement and methodological gaps

Empiric studies exploring the timeliness of routine vaccination in low-and middle-income countries (LMICs) have gained momentum in the last decade. Nevertheless, there is emerging evidence suggesting that these studies have key measurement and methodological gaps that limit their comparability and utility. Hence, there is a need to identify, and document these gaps which could inform the design, conduct, and reporting of future research on the timeliness of vaccination. We synthesised the literature to determine the methodological and measurement gaps in the assessment of vaccination timeliness in LMICs. We searched five electronic databases for peer-reviewed articles in English and French that evaluated vaccination timeliness in LMICs, and were published between 01 January 1978, and 01 July 2021. Two reviewers independently screened titles and abstracts and reviewed full texts of relevant articles, following the guidance framework for scoping reviews by the Joanna Briggs Institute. From the 4263 titles identified, we included 224 articles from 103 countries. China (40), India (27), and Kenya (23) had the highest number of publications respectively. Of the three domains of timeliness, the most studied domain was 'delayed vaccination' [99.5% (223/224)], followed by 'early vaccination' [21.9% (49/224)], and 'untimely interval vaccination' [9% (20/224)]. Definitions for early (seven different definitions), untimely interval (four different definitions), and delayed vaccination (19 different definitions) varied across the studies. Most studies [72.3% (166/224)] operationalised vaccination timeliness as a categorical variable, compared to only 9.8% (22/224) of studies that operationalised timeliness as continuous variables. A large proportion of studies [47.8% (107/224)] excluded the data of children with no written vaccination records irrespective of caregivers' recall of their vaccination status. Our findings show that studies on vaccination timeliness in LMICs has measurement and methodological gaps. We recommend the development and implement of guidelines for measuring and reporting vaccination timeliness to bridge these gaps.

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.

Timeliness of routine childhood vaccinations in Indonesian infants in the first year of life

BACKGROUND

Vaccines have proven to be one of the most effective strategies to control infectious diseases and contributed to childhood survival. While high vaccine coverages provide individual's and herd immunity, age-appropriate vaccination or vaccine timeliness is important for maximum vaccine's protection, but often not evaluated. We aimed to describe the timeliness of childhood vaccination for Indonesian infants and identify risk factors associated with delayed vaccination.

METHODS

This study was a sub-study of the Indonesian Pneumonia and Vitamin D status (IPAD) study, a community-based cohort study to investigate pneumonia incidence in two districts in Yogyakarta province, Indonesia. Socio-demographic data were obtained from structured interviews and vaccine status was obtained from maternal and child health records. Timely vaccination was defined if the vaccine was received between four days or less before and within 28 days after the recommended age of vaccination.

RESULTS

359 (85%) out of 422 IPAD participants and their immunisation records were included. Between December 2015 and December 2017, vaccination coverage was high and ranged from 96.1% (Measles) to 100% (DTP-HepB-Hib 1). However, two thirds (67%, 242/359) of all participants had received either early or late vaccines, with dose 2 IPV (40%, 143/356), dose 3 IPV (56%, 196/349) and dose 3 DTP-HepB-Hib (29%, 103/354) most delayed, and only 1% received early doses. The main risk factors for untimely vaccination were if the infant was born in a private practice versus in a public health facility (AOR 1.90; 95% CI: 1.18-3.07) and rural residence (AOR 1.84; 95% CI: 1.15-2.94).

CONCLUSIONS

Despite high vaccine coverage for Indonesian infants (>95%), two thirds (67%) of infants had untimely vaccinations, with dose 3 IPV (56%) the most delayed. Future strategies should focus on coordination between government, health care providers, and carers to ensure timely access and vaccination of infants to ensure adherence to vaccination schedules.

Descriptive analysis of routine childhood immunisation timeliness in the Western Cape, South Africa

Adherence to recommended age-specific immunisation schedules is critical in ensuring vaccine effectiveness against vaccine preventable diseases (VPDs). There is limited data on immunisation timeliness in sub-Saharan Africa. Therefore, this study assessed the timeliness of age-specific routine childhood immunisation within the Western Cape Province of South Africa. Participant records (N = 709) from a prospective health-facility based study conducted in Cape Town, SA in 2012-2016 were analysed. The outcome measure was receiving age-specific immunisations ≥4 weeks of that recommended for age as per the South African Expanded Programme on Immunisation (EPI-SA) schedule. Proportions, medians, inter-quartile ranges (IQR) and regression were used to obtain the prevalence, time-at-risk, and risk factors for delayed immunisation. A total of 652 /709 (91.9%) participants were eligible. Immunisation coverage declined with age from 94.9% (95% CI 92.9-96.4) at birth to 72.0% (95% CI 65.7-77.6) at 18 months. The highest delay in the uptake of vaccine doses was observed among the 3 rd dose of the DTP vaccine [163 (34.6% (95% CI 30.3-39.1)], while the lowest was seen among BCG [40 (6.5% (95% CI 4.7-8.8)]. The longest median time-at-risk of VPDs was among the 2 nd dose of the measles vaccine [12.9 (IQR 6.7-38.6) weeks] and the lowest was OPV birth dose [IQR 6.3 (5.3-9.1) weeks]. Low and upper-middle socio-economic quartiles were associated with delayed uptake of vaccine doses. Delayed vaccination increases the time of susceptibility to VPDs during infancy and childhood. There is a need to develop strategies aimed at mitigating factors associated with delay in uptake of routine childhood vaccines in the Western Cape. Mitigation strategies should provide vaccine education and mobile reminder systems. Education about timely vaccine uptake will aid in the provision of informed council from healthcare providers to caregivers. Multiple reminder systems could cater for low network coverage areas and caregivers with busy schedules.

Vaccination timeliness and associated factors among children aged 12-23 months in Debre Libanos district of North Shewa Zone, Oromia Regional State, Ethiopia

BACKGROUND

Globally, vaccination is one of the most cost-effective interventions in promoting child survival, preventing 2-3 million child deaths annually from vaccine-preventable diseases (VPDs). In Ethiopia, timely vaccination is stated as key to the prevention of unnecessary childhood mortality from measles, pneumonia, diarrheal diseases, and other VPDs. However, Ethiopia ranked fifth among the ten countries with the most unprotected children. Furthermore, previous vaccine timeliness studies produced widely disparate results. As a result, it was suggested that more research be conducted to investigate the potential factors behind the high proportion of untimely vaccination. Therefore, this study was intended to explore the association between different factors and the proportion of vaccination timeliness administered under the Expanded Program on Immunization in Debre Libanos district, Ethiopia.

METHODS

A community-based cross-sectional study design was employed from 1 May to 30 May 2021 among children aged 12 to 23 months with their mother/caregiver, who had started vaccination and had vaccination cards in the Debre Libanos. Simple random sampling techniques and pretested semi-structured questionnaires were used for data collection. At last, a multivariable logistic regression was used to identify factors associated with the vaccination timeliness.

RESULT

In this study, 413 children aged 12 to 23 months were interviewed with their mother/caregiver. Overall, 33.7% [95% CI (29.1-38.3)] of children received their vaccines timely. Having a female child [AOR: 2.9, 95% CI: 1.58-5.35], mother/caregiver attending primary [AOR: 6.33, 95% CI: 2.66-15.06] and secondary/above education [AOR: 5.61, 95% CI: 2.41-13.04], sufficient vaccination knowledge [AOR: 3.46, 95% CI: 1.87-6.38], mother/caregiver with least hesitant [AOR: 3.35, 95% CI: 1.51-7.41] and middle hesitant [AOR: 1.89, 95% CI: 1.05-3.58], utilization of ANC [AOR: 2.89, 95% CI: 1.32-6.33], and giving birth at health facility [AOR: 4.32, 95% CI: 1.95-9.59] were the factors independently associated with vaccination timeliness.

CONCLUSION

In comparison to Ethiopia's existing vaccination coverage, the proportion of children immunized at the recommended time interval is low in the study district. Policymakers should prioritize vaccine timeliness and integrate it into childhood vaccination strategies.

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.

Age-appropriate vaccination coverage and its determinants in children aged 12-36 months in Nepal: a national and subnational assessment

Background

Vaccination is one of the effective ways to develop immunity against potential life-threatening diseases in children in early age. This study is focused on analysing the age-appropriate vaccination coverage at national and subnational levels and identify the factors associated with age-appropriate coverage in Nepal.

Methods

460 children aged 12–36 months were included in the study. The data was obtained from Nepal Demographic and Health Survey (NDHS) 2016–17. Age-appropriate coverage of Bacillus Calmette-Guerin vaccine (BCG), oral polio vaccine (OPV) doses 1–3, pentavalent vaccine (PE) doses 1–3, and first dose of measles, mumps, and rubella vaccine (MMR) were estimated using Kaplan Meier method. Multilevel logistic regression with random intercept was used to identify the factors associated with age-appropriate vaccination.

Results

The crude coverage of the vaccines included in the study ranged from 91.5% (95% CI, 88.5–93.7) for PE3 to 97.8% (95.8–98.7) for BCG. Although the crude coverage of all the vaccines was above 90%, the age-appropriate coverage was significantly low, ranging from 41.5% (36.5–46.6) for PE3 to 73.9% (69.2–78.1) for PE1. Furthermore, high disparity in timely vaccination coverage was observed at regional level. Compared to the age-appropriate vaccination coverage in other provinces, Province 2 had the lowest coverage of all, followed by that in Province 6. The timeliness of vaccination was significantly associated with subnational regions i.e., provinces and the season of childbirth.

Conclusion

Although the immunization program in Nepal has achieved the target of 90% crude coverage of all the childhood vaccines, the age-appropriate coverage is significantly low which undermines the effectiveness of the vaccines administered. Thus, along with crude coverage, timeliness of the vaccines administered should be taken into consideration and thoroughly monitored at national and subnational levels. Provincial government should formulate tailored strategies to ensure the timely administration of the childhood vaccines.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-11841-2.

Which young women are not being vaccinated against HPV? Cross-sectional analysis of a UK national cohort study

OBJECTIVES

HPV vaccination is highly effective in preventing HPV-associated disease, including cervical cancer, which disproportionately affects women from disadvantaged and minority ethnic backgrounds. We examined inequalities in initiation of the HPV vaccination schedule among young women in the UK and reasons given by their parents for non-initiation.

DESIGN

Cross sectional analyses of a prospective nationally representative cohort study.

SETTING

Four UK countries.

PARTICIPANTS

5,695 young women (39.9% from households in lowest income quintiles, 5.1% ever excluded from school, 0.5% not attending school) whose parents (14.3% from minority ethnic backgrounds; 54.1% with no stated religious faith) took part in interviews conducted when their daughters were 14 years old.

MAIN OUTCOME MEASURES

Parent-reported initiation of HPV vaccination and reasons for non-initiation. The adjusted odds (aORs) and 95% Confidence Intervals (CI) of initiating HPV vaccination were estimated using logistic regression after mutual adjustment for household income, school exclusion, school attendance and parental ethnic background and religious faith.

RESULTS

92.3% (5265) had initiated HPV vaccination at time of interview. Initiation was less likely among those living in the poorest households (aOR; 95% CI: 0.44; 0.30 to 0.64 for those in lowest household income quintile), who did not attend school (0.11; 0.04 to 0.33), had ever been excluded from school (0.47; 0.29 to 0.76), or whose parents were from Black African (0.49; 0.26 to 0.95) or Any Other (0.34; 0.17 to 0.66) ethnic backgrounds. A reason consistent with a conscious or practical decision was reported by 53.3% (219) and 24.1% (90) parents respectively.

CONCLUSIONS

Although most young women are immunised, marked social inequalities in access to HPV vaccination initiation remain. Practical steps to address this are possible and should be implemented to reduce inequalities in primary prevention of cancers and to ensure equitable access to this important public health intervention.

Timeliness of routine childhood vaccination in low- and middle-income countries, 1978-2021: Protocol for a scoping review to map methodologic gaps and determinants

The literature on the timeliness of childhood vaccination (i.e. vaccination at the earliest appropriate age) in low-and middle-income countries has important measurement and methodological issues that may limit their usefulness and cross comparison. We aim to conduct a comprehensive scoping review to map the existing literature with a key focus on how the literature on vaccination timeliness has evolved, how it has been defined or measured, and what determinants have been explored in the period spanning the last four decades. This scoping review protocol was developed based on the guidance for scoping reviews from the Joanna Briggs Institute. We will include English and French language peer-reviewed publications and grey literature on the timeliness of routine childhood vaccination in low-and middle-income countries published between January 1978 through to 2021. A three-step search strategy that involves an initial search of two databases to refine the keywords, a full search of all included electronic databases, and screening of references of previous studies for relevant articles missing from our full search will be employed. The search will be conducted in five electronic databases: MEDLINE, EMBASE, Global Health, CINAHL and Web of Science. Google search will also be conducted to identify relevant grey literature on vaccination timeliness. All retrieved titles from the search will be imported into Endnote X9.3.3 (Clarivate Analytics) and deduplicated. Two reviewers will screen the titles, abstracts and full texts of publications for eligibility using Rayyan-the web based application for screening articles for systematic reviews. Using a tailored data extraction template, we will extract relevant information from eligible studies. The study team will analyse the extracted data using descriptive statistical methods and thematic analysis. The results will be presented using tables, while charts and maps will be used to aid the visualisation of the key findings and themes. The proposed review will generate evidence on key methodological gaps in the literature on timeliness of childhood vaccination. Such evidence would shape the direction of future research, and assist immunisation programme managers and country-level stakeholders to address the needs of their national immunisation system.

Timeliness of Childhood Vaccination Coverage: the Growing Up in Singapore Towards Healthy Outcomes Study

Studies investigating timeliness for childhood vaccination are limited especially in Asia. We examined the timeliness of vaccine administration and associated factors among infant and young children in Singapore. A total of 782 children born between November 2009 and July 2011 from a prospective cohort in Singapore were studied. Vaccination records from birth to 24 months of age were obtained from the National Immunization Registry of Singapore. Multivariable logistic regression models were performed. By 2 years of age, 92.8% of children in our cohort experienced a delay in receiving 1 or more vaccine doses according to the recommended national immunization schedule. When vaccinations were reviewed by series for each vaccine, 15.6% received all vaccine series outside the recommended age ranges. Factors associated with receiving vaccination series outside the recommended ages included maternal aged ≤ 35 years (OR 2.00; 95% CI 1.09, 3.66), Malay (1.71; 1.01, 2.89) or Indian ethnicity (2.06; 1.19, 3.59), low monthly household income (1.91; 1.14, 3.18), having at least four children (3.46; 1.62, 7.38) and private (3.42; 1.80, 6.48) and multiple vaccination providers (3.91; 1.23, 12.48). These findings show an unacceptably high proportion of children experienced a delay in the receipt of their vaccinations. The identification of several demographic, socioeconomic, health-seeking behavioural and vaccine provider factors provides opportunities for targeted interventions to enhance the timeliness of childhood vaccination in Singapore.

Critical Review of Data Analytics Techniques used in the Expanded Program on Immunization (EPI)

BACKGROUND

Immunization is a significant public health intervention to reduce child mortality and morbidity. However, its coverage, in spite of free accessibility, is still very low in developing countries. One of the primary reasons for this low coverage is the lack of analysis and proper utilization of immunization data at various healthcare facilities.

PURPOSE

In this paper, the existing machine learning-based data analytics techniques have been reviewed critically to highlight the gaps where this high potential data could be exploited in a meaningful manner.

RESULTS

It has been revealed from our review that the existing approaches use data analytics techniques without considering the complete complexity of Expanded Program on Immunization which includes the maintenance of cold chain systems, proper distribution of vaccine and quality of data captured at various healthcare facilities. Moreover, in developing countries, there is no centralized data repository where all data related to immunization is being gathered to perform analytics at various levels of granularities.

CONCLUSION

We believe that the existing non-centralized immunization data with the right set of machine learning and Artificial Intelligence-based techniques will not only improve the vaccination coverage but will also help in predicting the future trends and patterns of its coverage in different geographical locations.

Infant Vaccinations among Mothers with Substance-Use Disorders: A Comparative Study

Introduction: Infants of mothers with substance use disorder (SUD) are exposed to complex social environments and increased childhood health risks that can lead to adverse consequences throughout the lifespan. GunderKids, a voluntary, specialized, comprehensive pediatric care management program, was developed to mitigate many of these adverse consequences. Our organization is evaluating several clinical outcomes related to health and development in children born to women with SUD. The current study addressed the timeliness of vaccination coverage among these infants.Methods: This descriptive comparative preliminary study evaluated data of infants and their mothers with SUD who were previously identified during prenatal care visits either by self-report or by positive urine screens. Sociodemographic and vaccination data were extracted from a longitudinal master dataset of variables developed and maintained through retrospective review of electronic health records (EHRs) of these mothers and their infants. Timeliness of vaccination coverage of SUD-exposed infants participating in GunderKids was compared with that of SUD-exposed infants receiving standard pediatric care and was determined using a cumulative vaccinations method.Results: Overall, infants in the GunderKids group (n=50) had more timely vaccination coverage than those receiving standard pediatric care (n=20). Examples of timelier coverage included Haemophilus influenzae type b (Hib) at 4 months (P = .01; OR 4.3, 95% CI 1.4-13.4), for pneumococcal (P = .004; OR 6.6, 95% CI 1.8-23.8) and Hib (P = .004; OR 5.8, 95% CI 1.6-21.9) vaccinations at 15 months. More than 77% of GunderKids received all 6-month vaccinations in a timely manner compared with less than 45% of the standard care group; odds ratios suggest that GunderKids had 4.0-5.6 higher odds of receiving 6-month vaccinations.Conclusion: Vaccination coverage of infants participating in GunderKids was timelier than that of infants receiving standard pediatric care. Results suggest that specialized programs like GunderKids may assist in mitigating adverse health consequences and timeliness of vaccination coverage might be used as a proxy for measuring program effectiveness. Further investigation is recommended to determine clinical, individual, and organizational factors that influence parental behaviors and pediatric outcomes within SUD-exposed families.

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.

Inequities in On-Time Childhood Vaccination: Evidence From Sub-Saharan Africa

INTRODUCTION

Vaccination coverage has improved in the past decade, but inequalities persist: the poorest, least educated, and rural communities are left behind. Programming has focused on increasing coverage and reaching the hardest-to-reach children, but vaccination timeliness is equally important because delays leave children vulnerable to infections. This study examines the levels and inequities of on-time vaccination in the Sub-Saharan African region.

METHODS

The most recent Demographic and Health Surveys or Multiple Indicator Clusters Surveys since 2000 from Sub-Saharan Africa were used to assess on-time vaccination and inequalities by household wealth, maternal education, and place of residence. Inequalities were quantified using slope index of inequality and concentration index.

RESULTS

The analysis included 153,632 children aged 12-36 months from 40 Sub-Saharan Africa countries. Median on-time vaccination coverage was <50% in all the 4 subregions. Differences in on-time vaccination were observed by place of residence in the Southern (20.8 percentage points, 95% CI=0.8, 40.8), West (17.5 percentage points, 95% CI=5.1, 29.9), and Eastern (20.9 percentage points, 95% CI=6.5, 35.2) regions. Wealth-related inequities were observed in the Southern (22.6 percentage points, 95% CI=4.0, 41.2), Western (30.6 percentage points, 95% CI=19.1, 42.1), and Eastern (26.1 percentage points, 95% CI=8.2, 44.0) regions. Significant education-related differences in on-time vaccination were observed in the Western (20.7 percentage points, 95% CI=10.9, 30.5) and Eastern (21.2 percentage points, 95% CI=7.0, 35.4) regions.

CONCLUSIONS

On-time vaccination coverage was low in all subregions and nearly all countries. Inequalities in on-time immunization by household wealth, place of residence, and education existed in most countries. Concrete strategies to improve levels of timeliness are needed.

SUPPLEMENT INFORMATION

This article is part of a supplement entitled Global Vaccination Equity, which is sponsored by the Global Institute for Vaccine Equity at the University of Michigan School of Public Health.

Timeliness of immunisation with the pentavalent vaccine at different levels of the health care system in the Lao People's Democratic Republic: A cross-sectional study

Background

The timely administration of vaccines is considered to be important for both individual and herd immunity. In this study, we investigated the timeliness of the diphtheria-tetanus-whole cell pertussis-hepatitis B-Haemophilus influenzae type b (pentavalent) vaccine, scheduled at 6, 10 and 14 weeks of age in the Lao People’s Democratic Republic. We also investigated factors associated with delayed immunization.

Methods

1162 children aged 8–28 months who had received the full course of the pentavalent vaccine at different levels of the health care system were enrolled. Vaccination dates documented in hospital records and/or immunisation cards were recorded. Age at vaccination and time intervals between doses were calculated. Predictors for timely completion with the pentavalent vaccine at 24 weeks were assessed by bivariate and multivariable analyses.

Results

Several discrepancies in dates between vaccination documents were observed. In general, vaccination with the pentavalent vaccine was found to be delayed, especially in health care settings below the provincial hospital level. Compared to the central hospital level, less participants who were vaccinated at the district/health center level received the third dose by 16 (48% at the central hospital level vs. 7.1% at the district and 12.4% at the health center level) and 24 weeks of age (94.4% at the central hospital level vs 64.6% at the district-outreach and 57.4% at the health center level) respectively. In logistic regression analyses, lower education level of the mother as well as vaccination by outreach service, were independently associated with delayed completion of vaccination.

Conclusion

We observed a general delay of vaccination, especially at lower ranked facilities, which correlated with indicators of poor access to health services. This highlights the need for further improving health equity in rural areas. Age-appropriate vaccination should become a quality indicator for the national immunization programme. In addition, we recommend further training of the health care staff regarding the importance of reliable documentation of dates.

Impact of the COVID-19 Pandemic on Routine Childhood Immunization in Saudi Arabia

The COVID-19 pandemic is impacting national and international public health. Routine childhood immunization may be adversely affected by COVID-19 mitigation measures. We aimed to identify the prevalence of delayed immunization and explore the reasons and barriers for delayed immunization during the COVID-19 pandemic in the Qassim region, Saudi Arabia. We conducted a cross-sectional study using an online self-administered questionnaire for parents of children under two years of age during the period from 1 May to 30 June 2020. Most of the 749 participants (82.6%) were mothers, with 31 to 40 years being the most common age group (49.8%). Nearly three-quarters (73.2%) of the parents had appointments scheduled for their child’s vaccination during the pandemic, and approximately 23.4% of the parents reported a delay of more than one month in the immunization of their child. The most common reason for the delay was the fear of being infected by COVID-19 (60.9%). Large household size and lack of insurance were risk factors for immunization delay. The COVID-19 pandemic has affected the timeliness of routine childhood immunization in Saudi Arabia. Childhood immunization should be prioritized, as well as the implementation of focused strategies to achieve significant and sustainable vaccination rates during pandemics.

Impact of COVID-19 on vaccination programs: adverse or positive?

The COVID-19 pandemic has posed multiple substantial challenges, affecting not only public health but also economic systems, socio-cultural patterns, and political institutions. Studies have focused on the relationships between complex emergencies and natural disasters with outbreaks of infectious diseases. However, there is a dearth of relevant literature on the impact of a global pandemic on vaccination programs - an important topic because delays or stops in such programs are likely to result in outbreaks and epidemics of other infectious diseases. Thus, this article discusses the negative and positive impacts that the COVID-19 pandemic may exert on vaccination for vaccine-preventable diseases (VPDs). Negative impacts include the increased risk of VPD outbreaks in low-resource countries where vaccination programs must be temporarily halted to prevent the spread of infection. Positive effects include the strong possibility that the universally-recognized need for a coronavirus vaccine may increase people's appreciation for vaccines in general, resulting in improved vaccination uptake once the pandemic passes. Concerned stakeholders, such as governments and the World Health Organization (WHO), should seize this moment to effectively build on these positive impacts by planning renewed and revitalized post-COVID vaccination programs.

A data-driven framework for introducing predictive analytics into expanded program on immunization in Pakistan

BACKGROUND

Pakistan has a nationwide expanded program on immunization (EPI), yet vaccination coverage in Pakistan is quite low. Recently, an analytical model has been proposed to improve the coverage by identifying children who are most likely to miss any of the vaccines included in the immunization schedule, known as defaulters; however, a number of limitations remain unresolved in the previously proposed model. Firstly, it only classified children into two stages: defaulters and non-defaulters, considering all children at high risk of defaulting even if only one dose is missed. Secondly, there was no categorisation of high and low coverage areas for prioritised vaccination. The aim of this study was to propose a prediction framework for the accurate identification of defaulters.

METHODS

We have utilised a sample dataset extracted from the Pakistan Demographic and Health Survey (PDHS, 2017-2018). This contained 7153 data records with 19 demographic and socioeconomic attributes, which were used for defaulter prediction and the identification of association rules to understand the relation between demographics of the child and the vaccination status.

RESULTS

Using a multilayer perceptron (MLP) classifier, the proposed model achieved 98% accuracy and 0.994 for the area under the curve (AUC), to correctly identify the children who are likely to default from immunization series at different risk stages.

CONCLUSION

The proposed framework in this study is a step forward towards a data-driven approach and provides a set of machine learning techniques to utilise predictive analytics. Hence, this can reinforce immunization programs by expediting targeted action to reduce drop-outs.

Timeliness and equity of infant pertussis vaccination in wales: Analysis of the three dose primary course

Infants aged under one year are at the highest risk of severe complications or death from pertussis infection. Prompt vaccination with a three dose course at two, three and four months of age decreases the amount of time they are vulnerable following waning of maternal antibodies. In Wales, uptake of all three doses of the primary course of pertussis containing vaccine is high. However, timeliness and equity at a population level have not been previously reported. This analysis included 163,733 children born from 1st January 2013 to 31st December 2017. In this cohort 87.9% received the first dose of a pertussis containing vaccine by 12 weeks of age, 87.1% had received all three doses by 24 weeks of age, and 96.3% received three doses by 52 weeks of age. Differences in uptake between those living in the most deprived and least deprived quintiles of Lower Super Output Area (LSOA) were smaller than differences in timeliness, but statistically significant. In 2017 the difference in timely uptake between those living in the most and least deprived quintiles was 4%, 5% and 7% for doses one, two and three respectively. There was a difference of 10% in the proportion of infants receiving all three primary vaccinations on time between the most and least deprived quintile of LSOAs. Consideration is needed on interventions that will help improve timeliness such as enhanced follow up of defaulters, electronic communication between primary care data systems, enhanced health visitor intervention and opportunistic vaccination in those who fail to attend scheduled vaccination appointments. There is also the need for routine monitoring of timeliness and further research into what influences delayed vaccination.

Identifying inequalities in childhood immunisation uptake and timeliness in southeast Scotland, 2008-2018: A retrospective cohort study

BACKGROUND

In 2018, there was a record incidence of measles and other vaccine-preventable diseases across developed countries. Declining childhood immunisation uptake in southeast Scotland-an area with a large, highly mobile, and socioeconomically diverse population-threatens regional herd immunity and warrants investigation of suboptimal coverage. As deprivation of social and material resources increases risk of non-vaccination, we examined here the relationship between deprivation, uptake, and timeliness for four routine childhood vaccines and identified trends over the past decade.

METHODS

This retrospective cohort study analysed immunisation data from the Scottish Immunisation Recall System (SIRS) for four routine childhood vaccines in the UK: the third dose of the primary vaccine (TPV), both doses of measles, mumps, rubella (MMR 1 and MMR 2), and the preschool booster (PSB). Immunisations (N = 329,897) were administered between 2008 and 2018. Deprivation was measured via the Scottish Index of Multiple Deprivation (SIMD), ranking postcodes by deprivation decile. Chi-squared tests and cox proportional hazards models assessed the relationship between uptake, timeliness, and deprivation.

RESULTS

There is strong evidence for an association between deprivation, uptake, and timeliness. Uptake for all childhood immunisations are very high, especially for TPV and MMR 1 (>98.0%), though certain deprivation deciles exhibit increased risks of non-vaccination for all vaccines. Delay was pronounced for the 40% most deprived population and for immunisations scheduled at later ages. Absolute PSB and MMR 2 uptake has improved since 2008; however, disparities in uptake have increased for all vaccines since the 2006 birth cohort.

CONCLUSION

Both timeliness and uptake are strongly associated with deprivation. While absolute uptake was high for all vaccines, relative uptake and timeliness has been worsening for most groups; the reason for this decline is unclear. Here we identified subgroups that may require targeted interventions to facilitate uptake and timeliness for essential childhood vaccines.

[Psychological antecedents of vaccination: definitions, measurement, and interventions]

Vaccinations are among the safest and most effective ways to prevent morbidity and mortality from severe infectious diseases - both on an individual and societal level. Despite the availability of safe and effective vaccines some people decide against vaccination, which leads to recurrent outbreaks of vaccine-preventable diseases. In order to achieve the common goals of eliminating certain infectious diseases and to protect individual health, it is necessary to understand the antecedents of (non-)vaccination.The 5C model describes five relevant psychological antecedents of vaccination: confidence, complacency (risk perceptions), constraints (barriers), calculation (extent of information search), and collective responsibility (willingness to protect the community). This contribution provides an overview of how these antecedents can be measured on an individual level and how interventions should be designed and evaluated to address the respective antecedents.Data from Germany show that structural changes to reduce practical barriers are important to improve vaccine uptake. Thus, it is also important to address aspects beyond confidence.

Vaccine Coverage among Children with and without Intellectual Disabilities in the UK: Cross Sectional Study

BACKGROUND

Universal childhood vaccination programmes form a core component of child health policies in most countries, including the UK. Achieving high coverage rates of vaccines is critical for establishing 'herd immunity' and preventing disease outbreaks. Evidence from the UK has identified several groups of children who are at risk of not being fully immunised. Our aim was to determine whether children with intellectual disabilities constitute one such group.

METHODS

Secondary analysis of parental report data on child vaccination collected in the UK's Millennium Cohort Study when the children were 9 months, 3 years, 5 years and 14 years old.

RESULTS

With one exception (MMR coverage at age 5) vaccination coverage rates were lower for children with intellectual disabilities (when compared to children without intellectual disability) for all vaccinations at all ages. Complete coverage rates were significantly lower for children with intellectual disabilities at ages 9 months (unadjusted PRR non-vaccination = 2.03 (1.14-3.60), p < 0.05) and 3 years (unadjusted PRR = 2.16 (1.06-4.43), p < 0.05), but not at age 5 years (unadjusted PRR = 1.91 (0.67-5.49)). HPV vaccination was lower (but not significantly so) at age 14 (PRR = 1.83 (0.99-3.37), p = 0.054). Adjusting PRRs for between group differences in family socio-economic position and other factors associated with coverage reduced the strength of association between intellectual disability and coverage at all ages. However, incomplete vaccination remained significantly elevated for children with intellectual disabilities at ages 9 months and 3 years. There were no statistically significant differences between parents of children with/without intellectual disability regarding the reasons given for non-vaccination.

CONCLUSIONS

Children with intellectual disabilities in the UK are at increased risk of vaccine preventable diseases. This may jeopardise their own health, the health of younger siblings and may also compromise herd immunity.

Record linkage to enhance consented cohort and routinely collected health data from a UK birth cohort

Background

In longitudinal health research, combining the richness of cohort data to the extensiveness of routine data opens up new possibilities, providing information not available from one data source alone. In this study, we set out to extend information from a longitudinal birth cohort study by linking to the cohort child’s routine primary and secondary health care data. The resulting linked datasets will be used to examine health outcomes and patterns of health service utilisation for a set of common childhood health problems. We describe the experiences and challenges of acquiring and linking electronic health records for participants in a national longitudinal study, the UK Millennium Cohort Study (MCS).

Method

Written parental consent to link routine health data to survey responses of the MCS cohort member, mother and her partner was obtained for 90.7% of respondents when interviews took place at age seven years in the MCS. Probabilistic and deterministic linkage was used to link MCS cohort members to multiple routinely-collected health data sources in Wales and Scotland.

Results

Overall linkage rates for the consented population using country-specific health service data sources were 97.6% for Scotland and 99.9% for Wales. Linkage rates between different health data sources ranged from 65.3% to 99.6%. Issues relating to acquisition and linkage of data sources are discussed.

Conclusions

Linking longitudinal cohort participants with routine data sources is becoming increasingly popular in population data research. Our results suggest that this is a valid method to enhance information held in both sources of data.

Vaccine coverage and compliance in Mexico with the two-dose and three-dose rotavirus vaccines

Worldwide, rotavirus infection has been a leading cause of severe diarrhea morbidity and mortality. Two rotavirus vaccines have been used in the National Immunization Program (NIP) in Mexico; two-dose Rotarix from 2006 to 2011 and three-dose RotaTeq since 2011. This study assessed coverage (receiving at least one dose or full dose series) in eligible infants, compliance (% completing dose series and % completing series on schedule) in eligible infants vaccinated with Rotarix (2010) versus RotaTeq (2012), using Mexican Social Security Institute data nationwide and by regions. In 2010, 80.7% received at least one dose of Rotarix, 75.6% received both doses and 57.0% received both doses on schedule. In 2012, 85.7% received at least one dose of RotaTeq, 61.0% received all three doses and 43.2% received all three doses on schedule. More eligible infants received all doses with Rotarix versus RotaTeq (p < 0.001). Among infants vaccinated with Rotarix versus RotaTeq, 93.7% versus 71.1% completed full series (p < 0.001), and 75.5% versus 70.9% completed full series on schedule (p = 0.105), respectively. The full series coverage and compliance decreased in all regions with RotaTeq compared with Rotarix. In conclusion, rotavirus vaccination has successfully reduced morbidity and mortality in children under 5 years in Mexico. This study found significant differences in full series coverage and compliance among infants and a higher proportion of completed scheduled at an earlier age in Mexico when comparing a two-dose vaccine in 2010 with a three-dose vaccine in 2012. Such differences might need to be taken into consideration to maximize NIP benefits, including early protection of the rotavirus vaccination program.

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.

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.

Assessment of on-time vaccination coverage in population subgroups: A record linkage cohort study

Reported infant vaccination coverage at age 12 months in Australia is >90%. On-time coverage of the 2-4-6 month schedule and coverage in specific populations is rarely reported. We conducted a population-based cohort study of 1.9 million Australian births, 1996-2012, combining individual birth and perinatal records with immunisation records through probabilistic linkage. We assessed on-time coverage across 13 demographic and perinatal characteristics of diphtheria-tetanus-pertussis vaccines (DTP) defined as vaccination 14 days prior to the scheduled due date, to 30 days afterwards. On-time DTP vaccination coverage in non-Aboriginal infants was 88.1% for the 2-month dose, 82.0% for 4-month dose, and 76.7% for 6-month dose; 3-dose coverage was 91.3% when assessed at 12 months. On-time DTP coverage for Aboriginal infants was 77.0%, 66.5%, and 61.0% for the 2-4-6 month dose; 3-dose coverage at 12 months was 79.3%. Appreciable differences in on-time coverage were observed across population subgroups. On-time coverage in non-Aboriginal infants born to mothers with ≥3 previous pregnancies was 62.5% for the 6-month dose (47.9% for Aboriginal infants); up to 23.5 percentage points lower than for first-borns. Infants born to mothers who smoked during pregnancy had coverage 8.7-10.3 percentage points lower than infants born to non-smoking mothers for the 4- and 6-month dose. A linear relationship was apparent between increasing socio-economic disadvantage and decreasing on-time coverage. On-time coverage of the 2-4-6 month schedule is only 50-60% across specific population subgroups representing a significant avoidable public health risk. Aboriginal infants, multiparous mothers, and those who are socio-economically disadvantaged are key groups most likely to benefit from targeted programs addressing vaccine timeliness.