A population-based cohort study of undervaccination in 8 managed care organizations across the United States

Identification of Spatial Clusters of Undervaccination Patterns Among Children Aged <24 Months Using Immunization Information System Data, Montana, 2015-2019

OBJECTIVE

Spatial clustering of undervaccination leads to increased risk of vaccine-preventable diseases. We identified spatial clustering of undervaccination patterns among children aged <24 months in Montana.

METHODS

We used Montana's immunization information system data to analyze deidentified vaccination records of children aged <24 months born from January 2015 through November 2017. We measured 3 outcomes that were not mutually exclusive: not completing the combined 7-vaccine series by age 24 months, having an undervaccination pattern indicative of parental hesitancy, and having an undervaccination pattern indicative of structural barriers to timely vaccination. Using geomasked residential addresses, we conducted separate Bernoulli spatial scans with a randomization P < .01 to identify spatial clusters consisting of ≥100 children for each outcome and calculated the relative risk of having the undervaccination pattern inside versus outside the cluster.

RESULTS

Of 31 201 children aged <24 months included in our study, 11 712 (37.5%) had not completed the combined 7-vaccine series by age 24 months, and we identified 5 spatial clusters of this outcome across Montana. We identified 4 clusters of undervaccination patterns indicative of parental vaccine hesitancy, all in western Montana. The cluster with the largest relative risk (2.3) had a radius of 23.7 kilometers (n = 762 children, P < .001). We also identified 4 clusters of undervaccination patterns indicative of structural barriers, with 3 of the largest clusters in eastern Montana.

CONCLUSION

In Montana, different strategies to increase routine and timely childhood vaccination are needed in distinct areas of this large and predominantly rural state. Immunization information system data can pinpoint areas where interventions to increase vaccination uptake are needed.

Vaccination Timeliness Among US Children Aged 0-19 Months, National Immunization Survey-Child 2011-2021

Importance

Delays in receiving vaccinations lead to greater vaccine-preventable disease risk. Timeliness of receipt of recommended vaccinations is not routinely tracked in the US, either overall or for populations that have known barriers to accessing routine health care, including lower-income families and children.

Objective

To measure vaccination timeliness among US children aged 0 to 19 months, overall and by socioeconomic indicators.

Design, Setting, and Participants

This serial, cross-sectional study analyzed nationally representative data from the 2011 to 2021 National Immunization Survey-Child (NIS-Child), an annual survey of parents, with immunization histories collected from clinicians administering vaccines. The 2020 and 2021 surveys largely reflected vaccinations in the US before the COVID-19 pandemic. Study participants included US children surveyed at ages 19 to 35 months. Data were analyzed from January to August 2023.

Exposure

Survey year.

Main Outcomes and Measures

The primary outcomes were average days undervaccinated (ADU) and percentage of children who received all vaccine doses on time (ie, 0 days undervaccinated) for the combined 7-vaccine series up to age 19 months. The mean adjusted annual change in on-time vaccination by socioeconomic indicators was calculated by use of multivariable log-linked binomial regression models.

Results

The surveys included 179 154 children (92 248 boys [51.2%]); 74 479 (31.4%, weighted) lived above the federal poverty level with more than $75 000 in annual family income, 58 961 (32.4%) lived at or above the poverty level with $75 000 or less in annual family income, and 39 564 (30.2%) lived below the poverty level. Overall, the median (IQR) ADU for the combined 7-vaccine series in the US decreased from 22.3 (0.4-71.5) days in the 2011 survey to 11.9 (0.0-55.5) days in the 2021 survey. The prevalence of on-time receipt of the combined 7-vaccine series increased from 22.5% (95% CI, 21.4%-23.6%) to 35.6% (95% CI, 34.2%-37.0%). Although children with more than $75 000 in annual family income had a 4.6% (95% CI, 4.0%-5.2%) mean annual increase in on-time vaccination, the mean annual increase was 2.8% (95% CI, 2.0%-3.6%) for children living at or above the poverty level with $75 000 or less in annual family income and 2.0% (95% CI, 1.0%-3.0%) for children living below the poverty level.

Conclusions and Relevance

In this cross-sectional study of NIS-Child data, improvements in vaccination timeliness were observed from the 2011 to the 2021 survey. However, widening disparities by socioeconomic indicators signal that increased efforts to facilitate timely vaccination among children in lower-income families are needed.

Delays in the vaccination of infants between 2 and 18 months of age: associated factors in Chile

INTRODUCTION

Infant vaccination has significantly reduced the morbidity and mortality of transmittable diseases worldwide. Its coverage is high (85%); however, partial or suboptimal vaccination has been an important public health problem. This study aimed (1) to design and explore the psychometric features of a questionnaire to determine the reasons for this partial or suboptimal vaccination; and 2) to determine the factors associated with delaying Diphtheria, Tetanus, Poliomyelitis (DTaP) vaccination.

MATERIAL AND METHODS

This study contained two parts. In Part One, a questionnaire was created by the research team and then validated by a committee of experts in the field and a group of parents. It included the following contents: sociodemographic variables, features of the vaccination services, history of vaccination, and attitudes and perceptions about vaccination. Part Two was a cross-sectional study, recruiting private and public healthcare centers to explore the psychometrics features of the instrument, performing exploratory factor analysis, and determining the associated factors with DTaP vaccination delay throughout multivariable regression models.

RESULTS

Initially, six experts validated the questionnaire. For instance, on a scale of 1 to 5, the general evaluation of the questionnaire was ≥ 4 for all the experts. Additionally, five experts considered that most of the questions were easy to understand, and all thought the questionnaire had a clear and logical organization. The resulting questionnaire included the "Trust and positive attitude towards vaccination" scale, which had a good structure of items and internal consistency (α = 0.7918). Six healthcare centers were recruited in the second part of the study, and 715 people answered the questionnaire. Not being the mother who brings the child to the health center, having more than one child, and having a history of previous vaccination delays increased the risk of delaying vaccination. Attending the healthcare center for a reason other than only vaccination, obtaining information about vaccines from the Internet, and having higher trust and positive attitudes to vaccination reduced the risk of delay.

CONCLUSIONS

First study during the pandemic to explore the role of different factors on the risk of DTaP vaccination delay in Latin America. The findings highlighted the importance of trust in the vaccination system. The instrument presented in this article may help the scientific community evaluate future interventions to increase trust and positive attitudes toward the vaccination process.

Estimating Vaccine Hesitancy in Colorado by Using Immunization Information System Data

OBJECTIVES

Vaccine hesitancy is a complex issue that threatens global health. We used data from the Colorado Immunization Information System (CIIS) to quantify vaccine hesitancy.

METHODS

We examined immunization records from CIIS for patients age 2 up to 9 months to estimate vaccine hesitancy by tabulating the number of doses received per visit and comparing it with the number of expected doses based on recommendations of the Advisory Committee on Immunization Practices. We calculated the percentage of patients in each vaccine hesitancy group who were up to date on the 7-antigen series by age 35 months. We examined the distribution of vaccine-hesitant populations among vaccination providers who report to CIIS to estimate the difference in vaccine-hesitant patient populations among vaccination providers in Colorado.

RESULTS

Of 201 450 patients, 5147 (2.6%) consistently limited the number of shots received at each visit as compared with recommendations from the Advisory Committee on Immunization Practices; 166 927 (82.9%) patients did not limit the number of shots received; 5693 (2.8%) limited the number of shots received at >1 visit but not all visits; and 23 683 (11.8%) limited the number of shots received at only 1 visit. We found differences in vaccine hesitancy distributions among certain Colorado vaccination providers.

CONCLUSIONS

Immunization information system data, although sometimes incomplete, offer an opportunity to investigate state-level vaccine hesitancy. Areas of future research include performing similar analyses over time and determining geographic and socioeconomic factors that contribute to vaccine hesitancy.

Narrative versus statistical messages: The interplay of perceived susceptibility and misperceptions on vaccine intention

Although there is enough scientific evidence to show the benefits and safety of vaccines, vaccine rates are low, while misperceptions about vaccines are on the rise. The main purposes of the current study are to 1) examine the effects of narrative vs. statistical messages on vaccine intention, 2) test the mediating role of perceived expectancies, and 3) examine the moderating roles of perceived susceptibility and misperceptions on vaccine intention. Data were collected with an online experiment through Amazon Mturk. The online experiment was conducted via Qualtrics once the study was considered exempt by the Institutional Research Board of a large University in the U.S. A total of 300 participants aged 18 and above completed the survey. Findings show that perceived expectancies mediate the relationship between message manipulation and vaccine intention. Our findings also show a three-way interaction which indicates that among individuals with high misperceptions, statistical messages are more persuasive for individuals with high perceived susceptibility, while narrative messages are more influential for individuals with low perceived susceptibility.

Spatial distribution and determinants of childhood vaccination refusal in the United States

Parental refusal and delay of childhood vaccination has increased in recent years in the United States. This phenomenon challenges maintenance of herd immunity and increases the risk of outbreaks of vaccine-preventable diseases. We examine US county-level vaccine refusal for patients under five years of age collected during the period 2012-2015 from an administrative healthcare dataset. We model these data with a Bayesian zero-inflated negative binomial regression model to capture social and political processes that are associated with vaccine refusal, as well as factors that affect our measurement of vaccine refusal. Our work highlights fine-scale socio-demographic characteristics associated with vaccine refusal nationally, finds that spatial clustering in refusal can be explained by such factors, and has the potential to aid in the development of targeted public health strategies for optimizing vaccine uptake.

Immunisation rates and predictors of undervaccination in infants with CHD

Vaccination coverage for infants with CHD is unknown, yet these patients are at high risk for morbidity and mortality associated with vaccine-preventable illnesses. We determined vaccination rates for this population and identified predictors of undervaccination. We prospectively enrolled infants with CHD born between 1 January, 2012 and 31 December, 2015, seen in a single-centre cardiology clinic between 15 February, 2016 and 28 February, 2017. We assessed vaccination during the first year of life. Subjects who by age 1 year received all routine immunisations recommended during the first 6 months of life were considered fully vaccinated. We also evaluated influenza vaccination during subjects' first eligible influenza season. We obtained immunisation histories from primary care providers and collected demographic and clinical data via a parent survey and chart review. We used multivariable logistic regression to identify predictors of undervaccination. Among 260 subjects, only 60% were fully vaccinated. Vaccination rates were lowest for influenza (64.6%), rotavirus (71.1%), and Haemophilus influenzae type b (79.3%). Cardiac surgery with cardiopulmonary bypass during the first year of life was associated with undervaccination (51.5% versus 76.4% fully vaccinated, adjusted odds ratio 2.1 [95% confidence interval 1.1-3.9]). Other predictors of undervaccination were out-of-state primary care (adjusted odds ratio 2.7 [1.5-4.9]), multiple comorbidities (≥2 versus 0-1, adjusted odds ratio 2.0 [1.1-3.6]), and hospitalisation for >25% of the first year of life (>25% versus ≤25%, adjusted odds ratio 2.1 [1.1-3.9]). Targeted quality improvement initiatives focused on improving vaccination coverage for these infants, especially surrounding cardiac surgery, are needed.

Beyond Vaccination Coverage: Population-Based Measurement of Early Childhood Immunization Schedule Adherence

The immunization schedule recommended by the U.S. Advisory Committee on Immunization Practices (ACIP) provides a structure for how 10 different vaccine series should be administered to children in the first 18 months of life. Progress toward US early childhood immunization goals has largely focused on measuring vaccination coverage at age 24 months. However, standard vaccination coverage measures do not reflect whether children received vaccine doses by recommended ages, or whether vaccines were given concomitantly, per the schedule. In this paper, we describe innovations in population-level measurement of immunization schedule adherence through quantifying vaccination timeliness and undervaccination patterns. Measuring vaccination timeliness involves comparing when children received vaccine doses relative to ACIP age recommendations. To assess undervaccination patterns, children's vaccination histories are analyzed to determine whether they were vaccinated consistent with the ACIP schedule. Some patterns, such as spreading out vaccines across visits, are indicative of parental hesitancy. Other patterns, such as starting all recommended series but missing doses, are largely indicative of other immunization services delivery challenges. Since 2003, at least 12 studies have used National Immunization Survey-Child, immunization information system, or integrated health plan data to measure vaccination timeliness or undervaccination patterns at national or state levels. Moving forward, these novel measures can be leveraged for population-based surveillance of vaccine confidence, and for distinguishing undervaccination due to parental vaccine hesitancy from undervaccination due to other causes. Broader adoption of these measures can facilitate identification of targeted strategies for improving timely and routine early childhood vaccination uptake across the United States.

Childhood immunization and age-appropriate vaccinations in Indonesia

Background

Childhood immunization is a cost-effective way to protect individuals against communicable diseases. However, although there is a large literature on childhood immunization in Indonesia, there is a paucity of research on the age-appropriateness on measles and DTwP-3 vaccination, and the inequities in immunization coverage across Indonesia.

Methods

In this paper, using seven waves of data from the nationally representative Indonesia Demographic and Health Surveys (DHS) covering the period 1991- 2017, we empirically analyse the socio-economic and demographic factors influencing the uptake of four routine vaccines (BCG, Polio-3, DTwP-3, and Measles). Specifically, using multivariate regression analysis, we identify the socio-economic and demographic factors influencing childhood immunization coverage. We further analyse the socio-economic and demographic correlates of the age-appropriateness of the measles and DTwP-3 vaccination coverage.

Results

Our findings show that parental education and use of healthcare services are strong predictors of full immunization and age-appropriate vaccinations. This study also finds evidence of spatial heterogeneity in both full immunization rates and age-appropriate vaccinations for measles and DTwP-3 vaccines.

Conclusions

Our analysis finds that despite an improvement in the timing of vaccinations over the last two decades, a significant proportion of children continue to receive their measles and DTwP vaccinations age inappropriately. In particular, we find that maternal education and maternal engagement with healthcare services are critical in improving age appropriateness of vaccinations. From a policy perspective, these results call for concerted efforts by policy makers to address regional gaps in access to health services and immunization coverage, as well as to improve the age-appropriateness of vaccination.

Rates of childhood vaccine refusal in Turkey during 2016-2017: Regional causes and solutions

OBJECTIVE

Vaccine hesitancy is a growing problem globally. This study aimed to detect the rates of vaccine refusal (VR) during childhood in each province and region of Turkey from 2016 to 2017 and to evaluate the experiences of Expanded Programme on Immunization (EPI) managers regarding childhood VR and opinions to solve and reduce vaccine hesitancy in Turkey.

METHODS

VR was defined as the refusal to vaccinate for at least one vaccine in children aged 0-23 months. In this descriptive study, information on notified VR cases and recommended solutions from every province in Turkey was accessed by the local EPI manager for the period 2016-2017. The VR rates were calculated.

RESULTS

From 80 provinces, 8977 VR cases were detected in 2016 (VR rate 3.5‰) and 14,779 cases in 2017 (VR rate 5.9‰; p<0.001). One quarter of Family Health Units reported at least one case of VR. The highest VR rate in children aged under 2 years was in East Marmara (8.4‰) in 2016, and the West Anatolia Region (10.9‰) and East Marmara region (10.9‰) in 2017. Concerns about the vaccine content, harmfulness, and fears about adverse effects were the most common reasons underlying VR. Educating healthcare workers about vaccines and interpersonal communication skills, increasing patient information with informative brochures, and preventing anti-vaccination publications in the media were the most frequent recommendations to solve VR.

CONCLUSIONS

In Turkey, VR cases continue to increase. Correct and adequate information, effective communication, and trust between healthcare workers and parents can help reduce VR.

Evaluating vaccination coverage and timeliness in American Indian/Alaska Native and non-Hispanic White children using state immunization information system data, 2015-2017

Comprehensive estimates of vaccination coverage and timeliness of vaccine receipt among American Indian/Alaska Native (AI/AN) children in the United States are lacking. This study’s objectives were to quantify vaccination coverage and timeliness, as well as the proportion of children with specific undervaccination patterns, among AI/AN and non-Hispanic White (NHW) children ages 0–24 months in Montana, a large and primarily rural U.S. state. Data from Montana’s immunization information system (IIS) for children born 2015–2017 were used to calculate days undervaccinated for all doses of seven recommended vaccine series. After stratifying by race/ethnicity, up-to-date coverage at key milestone ages and the proportion of children demonstrating specific patterns of undervaccination were reported. Among n = 3,630 AI/AN children, only 23.1% received all recommended vaccine doses on-time (i.e., zero days undervaccinated), compared to 40.4% of n = 18,022 NHW children (chi-square p < 0.001). A greater proportion of AI/AN children were delayed at each milestone age, resulting in lower overall combined 7-vaccine series completion, by age 24 months (AI/AN: 56.6%, NHW: 64.3%, chi-square p < 0.001). As compared with NHW children, a higher proportion of AI/AN children had undervaccination patterns suggestive of structural barriers to accessing immunization services and delayed starts to vaccination. More than three out of four AI/AN children experienced delays in vaccination or were missing doses needed to complete recommended vaccine series. Interventions to ensure on-time initiation of vaccine series at age 2 months, as well initiatives to encourage completion of multi-dose vaccine series, are needed to reduce immunization disparities and increase vaccination coverage among AI/AN children in Montana.

Timely completion of childhood vaccination and its predictors in Burkina Faso

BACKGROUND

Despite important progress in global vaccination coverage, many countries are still facing preventable disease outbreaks. Timely vaccination is important in getting adequate protection against disease. In light of the paucity of relevant literature, this study investigated the timely completion of childhood routine immunization and identified factors associated with timely vaccination in Burkina Faso.

METHODS

We extracted data on child vaccination and other child characteristics from a household survey conducted across 24 districts in 2017. We extracted data on health system characteristics from a parallel facility survey. We applied a Kaplan-Meier time-to-event analysis to estimate timely vaccination coverage defined as the proportion of children that received a given vaccine in the period between three days before and 28 days after the recommended age. We used a Cox proportional hazard model with mixed effects to identify factors associated with timely vaccination.

RESULTS

In total, 3,138 children aged between 16 and 36 months who could present an immunization booklet were included in the study.The main finding is the existence of an important gap showing that timely vaccination coverage was lower than vaccination coverage. More specifically,this gap ranged from 16% for BCG to 43% for Penta 3. In addition, region and distance between the household and the nearest health facility were the main factors associated with timely full vaccination coverage and specifically for Penta3, MCV1 and MCV2.

CONCLUSIONS

This study highlights that timely vaccination coverage remains substantially lower than vaccination coverage. Timeliness of vaccination should therefore be considered as a metric to assess the status of immunization in a country. Geographical accessibility continues to represent a major barrier to timely vaccination, calling for specific interventions on both supply-side (e.g. outreach activities) and demand-side (e.g. vouchers or community-based interventions for vaccination) to counteract its negative effect.

Safety of measles and pertussis-containing vaccines in children with autism spectrum disorders

OBJECTIVES

To determine whether children aged 4-7 years with a diagnosis of autism spectrum disorders (ASD) were at increased risk of fever, febrile seizures, or emergency department (ED) visits following measles- or pertussis-containing vaccines compared with children without ASD.

METHODS

The study included children born between 1995-2012, aged 4-7 years at vaccination, and members of six healthcare delivery systems within Vaccine Safety Datalink. We conducted self-controlled risk interval analyses comparing rates of outcomes in risk and control intervals within each group defined by ASD status, and then compared outcome rates between children with and without ASD, in risk and control intervals, by estimating difference-in-differences using logistic regressions.

RESULTS

The study included 14,947 children with ASD and 1,650,041 children without ASD. After measles- or pertussis-containing vaccination, there were no differences in association between children with and without ASD for fever (ratio of rate ratio for measles-containing vaccine = 1.07, 95% CI 0.58-1.96; for pertussis-containing vaccine = 1.16, 95% CI 0.63-2.15) or ED visits (ratio of rate ratio for measles-containing vaccine = 1.11, 95% CI 0.80-1.54; for pertussis-containing vaccine = 0.87, 95% CI 0.59-1.28). Febrile seizures were rare. Pertussis-containing vaccines were associated with small increased risk of febrile seizures in children without ASD.

CONCLUSION

Children with ASD were not at increased risk for fever or ED visits compared with children without ASD following measles- or pertussis-containing vaccines. These results may provide further reassurance that these vaccines are safe for all children, including those with ASD.

Vaccine Administration in Children's Hospitals

OBJECTIVES

To examine inpatient vaccine delivery across a national sample of children's hospitals.

METHODS

We conducted a retrospective cohort study examining vaccine administration at 49 children's hospitals in the Pediatric Health Information System database. Children <18 years old admitted between July 1, 2017, and June 30, 2019, and age eligible for vaccinations were included. We determined the proportion of hospitalizations with ≥1 dose of any vaccine type administered overall and by hospital, the type of vaccines administered, and the demographic characteristics of children who received vaccines. We calculated adjusted hospital-level rates for each vaccine type by hospital. We used logistic and linear regression models to examine characteristics associated with vaccine administration.

RESULTS

There were 1 185 667 children and 1 536 340 hospitalizations included. The mean age was 5.5 years; 18% were non-Hispanic Black, and 55% had public insurance. There were ≥1 vaccine doses administered in 12.9% (95% confidence interval: 12.8-12.9) of hospitalizations, ranging from 1% to 45% across hospitals. The most common vaccines administered were hepatitis B and influenza. Vaccine doses other than the hepatitis B birth dose and influenza were administered in 1.9% of hospitalizations. Children had higher odds of receiving a vaccine dose other than the hepatitis B birth dose or influenza if they were <2 months old, had public insurance, were non-Hispanic Black race, were medically complex, or had a length of stay ≥3 days.

CONCLUSIONS

In this national study, few hospitalizations involved vaccine administration with substantial variability across US children's hospitals. Efforts to standardize inpatient vaccine administration may represent an opportunity to increase childhood vaccine coverage.

Vaccine timeliness and prevalence of undervaccination patterns in children ages 0-19 months, U.S., National Immunization Survey-Child 2017

OBJECTIVES

Typically, early childhood vaccination coverage in the U.S. is measured as the proportion of children by age 24 months who completed recommended vaccine series. However, these measures do not reflect whether vaccine doses were received at the ages recommended by the U.S. Advisory Committee on Immunization Practices, or whether children received vaccines concomitantly, per the ACIP recommended schedule. This study's objective was to quantify vaccine timeliness and prevalence of specific patterns of undervaccination in U.S. children ages 0-19 months.

METHODS

Using 2017 National Immunization Survey-Child data, we calculated days undervaccinated for the combined 7-vaccine series and distinguished undervaccination patterns indicative of parental vaccine hesitancy, such as spreading out vaccines across visits ("shot-limiting") or starting some but not all recommended vaccine series ("selective vaccination"), from other non-hesitancy patterns, such as missing final vaccine doses or receiving all doses, with some or all late. We measured associations between demographic, socioeconomic and other characteristics with undervaccination patterns using multivariable log-linked binomial regression. Analyses accounted for the complex survey design.

RESULTS

Among n = 15,333 U.S. children, only 41.2% received all recommended vaccine doses on-time by age 19 months. Approximately 20.9% of children had an undervaccination pattern suggestive of parental vaccine hesitancy, and 36.2% had other undervaccination non-hesitancy patterns. Uninsured children and those with lower levels of maternal education were more likely to exhibit undervaccination patterns suggestive of parental hesitancy. Lower levels of maternal education were also associated with other non-hesitancy undervaccination patterns.

CONCLUSIONS

More than half of children in the U.S. are undervaccinated at some point by 19 months of age. Ongoing assessment of vaccine timeliness and immunization schedule adherence could facilitate timely and targeted public health interventions in populations with high levels of undervaccination.

Vaccination and childhood epilepsies

INTRODUCTION

The evidence relating vaccination to febrile seizures and epilepsy is evaluated with an emphasis on febrile seizures (FS), Dravet syndrome (DS), West syndrome, and other developmental and epileptic encephalopathies.

METHODS

A systematic literature review using search words vaccination/immunization AND febrile seizures/epilepsy/Dravet/epileptic encephalopathy/developmental encephalopathy was performed. The role of vaccination as the cause/trigger/aggravation factor for FS or epilepsies and preventive measures were analyzed.

RESULTS

From 1428 results, 846 duplicates and 447 irrelevant articles were eliminated; 120 were analyzed.

CONCLUSIONS

There is no evidence that vaccinations cause epilepsy in healthy populations. Vaccinations do not cause epileptic encephalopathies but may be non-specific triggers to seizures in underlying structural or genetic etiologies. The first seizure in DS may be earlier in vaccinated versus non-vaccinated patients, but developmental outcome is similar in both groups. Children with a personal or family history of FS or epilepsy should receive all routine vaccinations. This recommendation includes DS. The known risks of the infectious diseases prevented by immunization are well established. Vaccination should be deferred in case of acute illness. Acellular pertussis DTaP (diphtheria-tetanus-pertussis) is recommended. The combination of certain vaccine types may increase the risk of febrile seizures however the public health benefit of separating immunizations has not been proven. Measles-containing vaccine should be administered at age 12-15 months. Routine prophylactic antipyretics are not indicated, as there is no evidence of decreased FS risk and they can attenuate the antibody response following vaccination. Prophylactic measures (preventive antipyretic medication) are recommended in DS due to the increased risk of prolonged seizures with fever.

Adults' Acceptance of COVID-19 Vaccine for Children in Selected Lower- and Middle-Income Countries

Since emergency approval of COVID-19 vaccines for children aged between 12 and 15 years old was recently obtained in the United States and Europe, we aimed to assess the willingness to vaccinate children with a COVID-19 vaccine in lower- and middle-income countries (LMICs). Therefore, we launched an online cross-sectional survey in several LMICs. Questions relating to socio-demographic information, knowledge of COVID-19, level of fear/worry of being infected with COVID-19, and willingness to vaccinate children with the COVID-19 vaccine at 50%, 75% and 95% effectiveness levels, were asked. Of the 6571 participants (mean age = 39 ± 14 years), 64.0%, 72.6%, and 92.9% were willing to vaccinate children at 50%, 75%, and 95% effectiveness levels, respectively. Respondents who were undergraduates, who were more worried/fearful about COVID-19, had higher knowledge scores regarding COVID-19, and a higher belief that COVID-19 vaccination is important to protect others, were more willing to accept COVID-19 vaccination of children. COVID-19 vaccination of children will limit the spread of the virus, especially in schools; it may decrease the need for school closures which has a negative effect on child development. Findings from this study are useful for health promotion strategies during COVID-19 vaccination implementation among children in LMICs.

Childhood vaccination timeliness following maternal migration to an informal urban settlement in Kenya

INTRODUCTION

Timely receipt of recommended vaccines is a proven strategy to reduce preventable under-five deaths. Kenya has experienced impressive declines in child mortality from 111 to 43 deaths per 1000 live births between 1980 and 2019. However, considerable inequities in timely vaccination remain, which unnecessarily increases risk for serious illness and death. Maternal migration is a potentially important driver of timeliness inequities, as the social and financial stressors of moving to a new community may require a woman to delay her child's immunizations. This analysis examined how maternal migration to informal urban settlements in Nairobi, Kenya influenced childhood vaccination timeliness.

METHODS

Data came from the Nairobi Urban Health and Demographic Surveillance System, 2002-2018. Migration exposures were migrant status (migrant, non-migrant), migrant origin (rural, urban), and migrant type (first-time, circular [previously resided in settlement]). Age at vaccine receipt (vaccination timeliness) was calculated for all basic vaccinations. Accelerated failure time models were used to investigate relationships between migration exposures and vaccination timeliness. Confounding was addressed using propensity score weighting.

RESULTS

Over one-third of the children of both migrants and non-migrants received at least one dose late or not at all. Unweighted models showed the children of migrants had shorter time to OPV1 and DPT1 vaccine receipt compared to the children of non-migrants. After accounting for confounding only differences in timeliness for DPT1 remained, with the children of migrants receiving DPT1 significantly earlier than the children of non-migrants. Timeliness was comparable among migrants with rural and urban origins and among first-time and circular migrants.

CONCLUSION

Although a substantial proportion of children in Nairobi's informal urban settlements do not receive timely vaccination, this analysis found limited evidence that maternal migration and migration characteristics were associated with delays for most doses. Future research should seek to elucidate potential drivers of low vaccination timeliness in Kenya.

The Childhood Vaccination Schedule and the Lack of Association With Type 1 Diabetes

OBJECTIVES

Safety studies assessing the association between the entire recommended childhood immunization schedule and autoimmune diseases, such as type 1 diabetes mellitus (T1DM), are lacking. To examine the association between the recommended immunization schedule and T1DM, we conducted a retrospective cohort study of children born between 2004 and 2014 in 8 US health care organizations that participate in the Vaccine Safety Datalink.

METHODS

Three measures of the immunization schedule were assessed: average days undervaccinated (ADU), cumulative antigen exposure, and cumulative aluminum exposure. T1DM incidence was identified by International Classification of Disease codes. Cox proportional hazards models were used to analyze associations between the 3 exposure measures and T1DM incidence. Adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) were calculated. Models were adjusted for sex, race and ethnicity, birth year, mother's age, birth weight, gestational age, number of well-child visits, and study site.

RESULTS

In a cohort of 584 171 children, the mean ADU was 38 days, the mean cumulative antigen exposure was 263 antigens (SD = 54), and the mean cumulative aluminum exposure was 4.11 mg (SD = 0.73). There were 1132 incident cases of T1DM. ADU (aHR = 1.01; 95% CI, 0.99-1.02) and cumulative antigen exposure (aHR = 0.98; 95% CI, 0.97-1.00) were not associated with T1DM. Cumulative aluminum exposure >3.00 mg was inversely associated with T1DM (aHR = 0.77; 95% CI, 0.60-0.99).

CONCLUSIONS

The recommended schedule is not positively associated with the incidence of T1DM in children. These results support the safety of the recommended childhood immunization schedule.

Vaccine coverage, timeliness and delay estimated from regional and national cross-sectional surveys in Ethiopia, 2016

Introduction

measures of vaccine timing require data on vaccination dates, which may be unavailable. This study compares estimates of vaccine coverage and timing; and compares regression techniques that model these measures in the presence of incomplete data.

Methods

this cross-sectional study used the 2016 Ethiopian Demographic and Health Survey (DHS), and a 2016 survey from Worabe, Ethiopia. Three measures of vaccine uptake were calculated: coverage (regardless of timing), timeliness (within 1 week of recommended administration), and delay (the number of days between the recommended and actual date of vaccination). Vaccine coverage and timeliness were modeled with logistic regressions. After excluding those without dates, vaccine delay was estimated using linear regression or survival analysis. Vaccine delay was also estimated using accelerated failure time (AFT) models.

Results

the DHS survey included 3819 children aged 12-60 months and the Worabe survey included 484 children aged 12-23 months. In the Worabe survey, vaccine coverage for pentavalent vaccine dose 3 was 87.4%, with 8.6% receiving it within 1 week, and 71.7% within 4 weeks; the median delay was 19 days. Predictors of outcomes were similar in both the Worabe survey and Ethiopian DHS, with the largest numbers of significant associations seen in models with vaccine coverage or delays (with AFT models) as the outcomes.

Conclusion

estimates of coverage may miss a substantial proportion of infants who have delayed vaccination. Accelerated failure time (AFT) models are useful to estimate vaccine delay because they include information from all respondents (those with full and partial data on vaccination dates) and are agnostic about an age limit for timely vaccination.

Facilitators and Barriers to Providing Vaccinations During Hospital Visits

BACKGROUND

Many children are undervaccinated at the time of hospital admission. Our objective was to explore the facilitators and barriers to vaccinating during hospitalization.

METHODS

We conducted qualitative interviews of parents, primary care pediatricians, emergency department (ED) physicians, and pediatric hospitalists. Parents of undervaccinated hospitalized children who were admitted through the ED were invited to participate. We used purposive sampling to identify physician participants. Semistructured interviews querying participants' perspectives on hospital-based vaccination were audiorecorded and transcribed. Parent demographics and physician practice characteristics were collected. Transcripts were analyzed for facilitators and barriers to vaccinating during acute hospital visits by using inductive content analysis. A conceptual framework was developed on the basis of the social ecological model.

RESULTS

Twenty-one parent interviews and 10 physician interviews were conducted. Of parent participants, 86% were female; 76% were white. Physician participants included 3 primary care pediatricians, 3 ED physicians, and 4 hospitalists. Facilitators and barriers fell under 4 major themes: (1) systems-level factors, (2) physician-level factors, (3) parent-provider interactional factors, and (4) parent- and child-level factors. Parent participants reported a willingness to receive vaccines during hospitalizations, which aligned with physician participants' experiences. Another key facilitator identified by parent and physician participants was the availability of shared immunization data. Identified by parent and physician participants included the availability of shared immunization data. Barriers included being unaware that the child was vaccine-eligible, parental beliefs against vaccination, and ED and inpatient physicians' perceived lack of skills to effectively communicate with vaccine-hesitant parents.

CONCLUSIONS

Parents and physicians identified several key facilitators and barriers to vaccinating during hospitalization. Efforts to provide inpatient vaccines need to address existing barriers.

Revisiting the 2014-15 Disneyland measles outbreak and its influence on pediatric vaccinations

The 2014-15 Disneyland measles outbreak that began at the California theme park in December 2014 sparked an international conversation regarding measles, vaccine hesitancy, and vaccine policies. The outbreak capped a year with the highest number of measles cases reported in two decades and came amidst increasing trends in nonmedical vaccine exemptions in California and elsewhere. Because of its sensational story line and spread among unvaccinated populations, the outbreak received a high level of media coverage that focused on vaccine hesitancy as a primary driver of the outbreak. This media coverage and the ostensible public support for vaccines that followed led some to hypothesize that the outbreak might have a "Disneyland effect," or a positive influence on the uptake of pediatric measles vaccine. This article reviews the facts of the outbreak and its context, and explores the evidence for the Disneyland outbreak causing an influence on U.S. pediatric vaccine-related beliefs and behaviors.

Exploring mechanisms of a web-based values-tailored childhood vaccine promotion intervention trial: Effects on parental vaccination values, attitudes, and intentions

A recent childhood vaccine promotion intervention trial showed no effects on vaccination outcomes relative to usual care. The purpose of this paper was to test assumptions and theory-based relationships underlying hypothesised mechanisms for two vaccine promotion educational websites (one tailored to parental values, beliefs, and intentions; one untailored) compared with usual care. This is a secondary analysis of a three-arm randomized controlled trial. Parental vaccine values, hesitancy, attitudes, and intention to vaccinate surveys were administered at baseline (≤2 months) and at 4-6 and 10-12 months of age. Vaccination was assessed using electronic health records. Analyses included random coefficient models and risk differences with exact confidence limits. Parental vaccine values were mostly stable over time. Vaccine attitudes were generally positive, with no differences among study arms. Both tailored and untailored website arms showed similar increases in intention to vaccinate more than usual care. Positive changes in intentions were associated with lower rates of late vaccination. Although attitudes and intentions predicted vaccination behavior and the intervention increased intention to vaccinate all on time, the web-based education and values-tailored messaging approaches were not effective at increasing vaccination rates. Intentions are necessary but insufficient targets for vaccine promotion interventions.

Association of Diphtheria-Tetanus-Acellular Pertussis Vaccine Timeliness and Number of Doses With Age-Specific Pertussis Risk in Infants and Young Children

IMPORTANCE

In most countries, the diphtheria-tetanus-acellular pertussis (DTaP) vaccine is administered as a 3-dose infant series followed by additional booster doses in the first 5 years of life. Short-term immunity from the DTaP vaccine can depend on the number, timing, and interval between doses. Not receiving doses in a timely manner might be associated with a higher pertussis risk.

OBJECTIVE

To examine the association between number and timeliness of vaccine doses and age-specific pertussis risk.

DESIGN, SETTING, AND PARTICIPANTS

This population-based, retrospective cohort study used Washington State Immunization Information System data and pertussis surveillance data from Public Health Seattle and King County, Washington. Included participants were children aged 3 months to 9 years born or living in King County, Washington, between January 1, 2008, and December 31, 2017. Data were analyzed from June 30 to December 1, 2019.

EXPOSURES

Being undervaccinated (receiving fewer than recommended doses at a given age) or delayed vaccination (not receiving doses within time frames recommended by Centers for Disease Control and Prevention).

MAIN OUTCOMES AND MEASURES

Suspected, probable, and confirmed pertussis diagnosis.

RESULTS

A total of 316 404 children (median age, 65.2 months [interquartile range, 35.3-94.1 months]; 162 025 boys [51.2%]) as of December 31, 2017, with 17.4 million person-months of follow-up were included in the analysis. A total of 19 943 children (6.3%) had no vaccines recorded in the Immunization Information System, 116 193 (36.7%) received a vaccine with a delay, and 180 268 (56.9%) were fully vaccinated with no delay. Delayed vaccination and undervaccination rates were higher for older children (17.6% delayed or undervaccinated at age 2 months for dose 1 at 3 months vs 41.6% at age 5 years for dose 5) but improved for successive birth cohorts (52.2% for 2008 birth cohort vs 32.3% for 2017 birth cohort). Undervaccination was significantly associated with higher risk of pertussis for the 3-dose primary series (adjusted relative risk [aRR], 4.8; 95% CI, 3.1-7.6), the first booster (aRR, 3.2; 95% CI, 2.3-4.5), and the second booster (aRR, 4.6; 95% CI, 2.6-8.2). However, delay in vaccination among children who received the recommended number of vaccine doses was not associated with pertussis risk.

CONCLUSIONS AND RELEVANCE

The results of this cohort study suggest that undervaccination is associated with higher pertussis risk. Short delays in vaccine receipt may be less important if the age-appropriate number of doses is administered, but delaying doses is not recommended. Ensuring that children receive all doses of pertussis vaccine, even if there is some delay, is important.

Temporal Trends in Undervaccination: A Population-Based Cohort Study

INTRODUCTION

Monitoring the trends in undervaccination, including that because of parental vaccine refusal or delay, can inform public health responses directed at improving vaccine confidence and vaccination coverage.

METHODS

A retrospective cohort study was conducted in the Vaccine Safety Datalink. The cohort included all children born in 2004-2017 with ≥3 well-child visits between ages 2 and 23 months. Using electronic health record-based vaccination data, the average days undervaccinated was calculated for each child. Undervaccination patterns were assessed through age 23 months. Temporal trends were inspected for inflection points and were analyzed using linear regression. Nested within the cohort study, a survey was conducted to compare parent reports of vaccine refusal or delay with observed vaccination patterns. Data were analyzed in 2020.

RESULTS

The study cohort consisted of 808,170 children. The percentage of children with average days undervaccinated=0 (fully vaccinated, no delays) rose from a nadir of 47.1% for the birth year 2008 to 68.4% for the birth year 2017 (p_trend<0.001). The percentage with no vaccines rose from 0.35% for the birth year 2004 to 1.28% for the birth year 2017 (p_trend<0.001). Consistent vaccine limiting was observed in 2.04% for the birth year 2017. Omission of measles, mumps, and rubella vaccine peaked at 4.76% in the birth year 2007 and declined thereafter (p_trend<0.001). On the parent survey (response rate 60.2%), a high proportion of parents of the most undervaccinated children reported refusing or delaying vaccines.

CONCLUSIONS

In a 14-year cohort study, vaccination timeliness has improved. However, the small but increasing number of children who received no vaccines by age 23 months warrants additional attention.

Estimating the Effectiveness of Rotavirus Vaccine Schedules

BACKGROUND

Important questions exist regarding the comparative effectiveness of alternative childhood vaccine schedules; however, optimal approaches to studying this complex issue are unclear.

METHODS

We applied methods for studying dynamic treatment regimens to estimate the comparative effectiveness of different rotavirus vaccine (RV) schedules for preventing acute gastroenteritis-related emergency department (ED) visits or hospitalization. We studied the effectiveness of six separate protocols: one- and two-dose monovalent rotavirus vaccine (RV1); one-, two-, and three-dose pentavalent rotavirus vaccine (RV5); and no RV vaccine. We used data on all infants to estimate the counterfactual cumulative risk for each protocol. Infants were censored when vaccine receipt deviated from the protocol. Inverse probability of censoring-weighted estimation addressed potentially informative censoring by protocol deviations. A nonparametric group-based bootstrap procedure provided statistical inference.

RESULTS

The method yielded similar 2-year effectiveness estimates for the full-series protocols; weighted risk difference estimates comparing unvaccinated children to those adherent to either full-series (two-dose RV1, three-dose RV5) corresponded to four fewer hospitalizations and 12 fewer ED visits over the 2-year period per 1,000 children. We observed dose-response relationships, such that additional doses further reduced risk of acute gastroenteritis. Under a theoretical intervention to fully vaccinate all children, the 2-year risk differences comparing full to observed adherence were 0.04% (95% CI = 0.03%, 0.05%) for hospitalizations and 0.17% (95% CI = 0.14%, 0.19%) for ED visits.

CONCLUSIONS

The proposed approach can generate important evidence about the consequences of delaying or skipping vaccine doses, and the impact of interventions to improve vaccine schedule adherence.

Timeliness of Early Childhood Vaccinations and Undervaccination Patterns in Montana

INTRODUCTION

Early childhood vaccination rates are lower in rural areas than those in urban areas of the U.S. This study's objective is to quantify vaccine timeliness and the prevalence of undervaccination patterns in Montana and to measure the associations between timeliness and series completion by age 24 months.

METHODS

Using records from January 2015 to November 2019 in Montana's centralized immunization information system, days undervaccinated were calculated for the combined 7-vaccine series. Undervaccination patterns indicative of certain barriers to vaccination, including parental vaccine hesitancy, were identified. Using multivariable log-linked binomial regression, the association between timing of vaccine delay and not completing the combined 7-vaccine series by age 24 months was assessed. Analyses were conducted in March 2020-August 2020.

RESULTS

Among 31,422 children, 38.0% received all vaccine doses on time; 24.3% received all doses, but some were received late; and 37.7% had not completed the combined 7-vaccine series. Approximately 18.7% had an undervaccination pattern suggestive of parental vaccine hesitancy, and 19.7% started all series but were missing doses needed for multidose series completion. Although falling behind on vaccinations at any age was associated with failing to complete the combined 7-vaccine series, being late at age 12-15 months had the strongest association (adjusted prevalence ratio=3.73, 95% CI=3.56, 3.91) compared with being on time at age 12-15 months.

CONCLUSIONS

Fewer than 2 in 5 Montana children were fully vaccinated on time for the combined 7-vaccine series. To increase vaccination rates, initiatives to increase vaccine confidence and remind parents to complete vaccine series are needed.

Addressing logistical barriers to childhood vaccination using an automated reminder system and online resource intervention: A randomized controlled trial

BACKGROUND

As the rates of vaccination decline in children with logistical barriers to vaccination, new strategies to increase vaccination are needed. The goal of this study was to develop and evaluate the effectiveness of the Vaccines For Babies (VFB) intervention, an automated reminder system with online resources to address logistical barriers to vaccination in caregivers of children enrolled in an integrated healthcare system. Effectiveness was evaluated in a randomized controlled trial.

METHODS

Qualitative interviews were conducted with parents of children less than two years old to identify logistical barriers to vaccination that were used to develop the VFB intervention. VFB included automated reminders to schedule the 6- and 12-month vaccine visit linking caregivers to resources to address logistic barriers, sent to the preferred mode of outreach (text, email, and/or phone). Parents of children between 3 and 10 months of age with indicators of logistical barriers to vaccination were randomized to receive VFB or usual well child care (UC). The primary outcome was percentage of days undervaccinated at 2 years of life. A difference in differences analysis was conducted.

RESULTS

Qualitative interviews with 6 parents of children less than 2 years of age identified transportation, scheduling challenges, and knowledge of vaccine timing as logistical barriers to vaccination. We enrolled 250 participants in the trial, 45% were loss to follow-up. There were no significant differences in vaccination uptake between those enrolled in UC or the VFB intervention (0.51%, p = 0.86). In Medicaid enrolled participants, there was a modest decrease in percentage of days undervaccinated in the VFB intervention compared to UC (6.3%, p = 0.07).

CONCLUSION

Automated Reminders and with links to heath system resources was not shown to increase infant vaccination uptake demonstrating additional resources are needed to address the needs of caregivers experiencing logistical barriers to vaccination.

Incidence of pediatric inflammatory bowel disease within the Vaccine Safety Datalink network and evaluation of association with rotavirus vaccination

BACKGROUND

Recent studies have reported an increase in Inflammatory bowel disease (IBD) incidence in young children, highlighting the need to better understand risk factors for the development of IBD. Licensed for use in infants in 2006, the oral, live-attenuated rotavirus vaccine has biologic plausibility for instigating inflammation of the gut mucosa as a pathway to immune dysregulation.

METHODS

Over a ten-year period, we evaluated incidence of IBD within a cohort of children under the age of ten, enrolled in seven integrated healthcare delivery systems. We conducted a nested case-control study to evaluate the association between rotavirus vaccination and IBD using conditional logistic regression. Cases were confirmed via medical record review and matched to non-IBD controls on date of birth, sex, and study site.

RESULTS

Among 2.4 million children under the age of 10 years, 333 cases of IBD were identified with onset between 2007 and 2016. The crude incidence of IBD increased slightly over the study period (p-value for trend = 0.046). Of the 333 cases, 227 (68%) were born prior to 2007. Forty-two cases born in 2007 or later, with continuous enrollment since birth were included in the case-control study and matched to 210 controls. The adjusted odds ratio for any rotavirus vaccination in IBD cases, compared to matched controls, was 0.72 (95% confidence interval 0.19-2.65).

CONCLUSIONS

Data from this large pediatric cohort demonstrate a small overall increase in IBD incidence in young children over a ten-year period. The data suggest that rotavirus vaccination is not associated with development of IBD.

Hepatitis B birth dose vaccination patterns in the military health System, 2014-2018

BACKGROUND

Since 2005, the universal hepatitis B (HepB) birth dose has been recommended for all medically stable infants weighing ≥2,000 g at birth. The timing of the birth dose provides a critical safeguard and prevents infection among infants born to HBsAg-positive mothers not identified prenatally. We assess infant HepB vaccination in the U.S. Department of Defense's Military Health System (MHS) to identify trends in vaccination coverage and sociodemographic factors associated with non-receipt of the birth dose, receiving the first HepB vaccine >3 days of life, and not receiving any HepB vaccine in the first 18 months of life utilizing parental refusal codes. To our knowledge, this is one of the first studies assessing trends in parental refusal of the HepB birth dose utilizing administrative claims parental refusal codes.

METHODS

We conducted a retrospective cohort analysis of MHS live births from January 1, 2014 through December 31, 2018 utilizing administrative claims data. Data were included from 44 hospitals in 24 unique states, territories, or countries. We analyzed diagnosis codes for vaccine refusal and vaccination and current procedural terminology (CPT) codes to identify vaccination patterns. Generalized linear mixed effects models with a logit link were used to assess factors associated with vaccination patterns.

RESULTS

HepB birth dose vaccination coverage increased from 79.6% in 2014 to 88.1% in 2018 (p < .0001). Refusal rates also increased from 3.7% in 2014 to 4.5% in 2018 (p < .0001). The percentage of patients with missing diagnosis codes for vaccine refusal or vaccination decreased from 16.7% in 2014 to 7.4% in 2018. Factors associated with non-receipt of the birth dose included earlier year of birth, white maternal race, higher maternal age, higher birth order, and longer infant length of stay in hospital.

CONCLUSION

Vaccination coverage for HepB birth dose is high in the MHS and increased over time; concurrently, refusal rates also increased over time. Utilizing administrative claims data has the benefit of differentiating reasons for non-receipt of the birth dose over time.

A primer on quantitative bias analysis with positive predictive values in research using electronic health data

OBJECTIVE

In health informatics, there have been concerns with reuse of electronic health data for research, including potential bias from incorrect or incomplete outcome ascertainment. In this tutorial, we provide a concise review of predictive value-based quantitative bias analysis (QBA), which comprises epidemiologic methods that use estimates of data quality accuracy to quantify the bias caused by outcome misclassification.

TARGET AUDIENCE

Health informaticians and investigators reusing large, electronic health data sources for research.

SCOPE

When electronic health data are reused for research, validation of outcome case definitions is recommended, and positive predictive values (PPVs) are the most commonly reported measure. Typically, case definitions with high PPVs are considered to be appropriate for use in research. However, in some studies, even small amounts of misclassification can cause bias. In this tutorial, we introduce methods for quantifying this bias that use predictive values as inputs. Using epidemiologic principles and examples, we first describe how multiple factors influence misclassification bias, including outcome misclassification levels, outcome prevalence, and whether outcome misclassification levels are the same or different by exposure. We then review 2 predictive value-based QBA methods and why outcome PPVs should be stratified by exposure for bias assessment. Using simulations, we apply and evaluate the methods in hypothetical electronic health record-based immunization schedule safety studies. By providing an overview of predictive value-based QBA, we hope to bridge the disciplines of health informatics and epidemiology to inform how the impact of data quality issues can be quantified in research using electronic health data sources.

Prevalence and correlates of vaccine attitudes and behaviors in a cohort of low-income mothers

The US is facing a rise in vaccine hesitancy, delay, and refusal, though little is known about these outcomes in socio-economically disadvantaged populations. This study examines the prevalence and correlates of vaccine attitudes and behaviors in a diverse cohort of low-income mothers receiving home visiting services. Survey data were collected from 813 recipients of evidence-based home visiting services in Wisconsin from 2013 to 2018. Analyses were performed to describe outcome measures of vaccine attitudes and self-reported completion, and multivariate regressions were used to test associations between vaccine-related outcomes and hypothesized correlates. Most women (94%) reported their children were up to date on vaccines; 14.3% reported having ever delayed vaccination. A small minority disagreed that vaccines are important (5.0%), effective (5.4%), and safe (6.2%), though a larger proportion responded ambivalently (10.9%–21.9%). Participants with greater trust in health care providers reported more positive overall vaccine attitudes (B = 0.24; 95% CI = 0.17, 0.31), a lower likelihood of vaccine delay (OR = 0.57; 95% CI = 0.46, 0.73), and a greater likelihood of being up to date on vaccines (OR = 1.79, 95% CI = 1.30, 2.44). Women with greater trust in a home visitor also rated vaccines more positively (B = 0.09; 95% CI = 0.02, 0.15), and women who reported better mental health were more likely to report their children were up to date (OR = 1.05; 95% CI = 1.02, 1.09). Compared to non-Hispanic whites, American Indians and non-Hispanic blacks had poorer vaccine-related outcomes. More research on vaccine attitudes and behaviors among higher-risk populations is needed to develop tailored strategies aimed at addressing vaccine hesitancy and underimmunization.

Individual and Neighborhood Factors Associated With Failure to Vaccinate Against Influenza During Pregnancy

Uptake of influenza vaccine among pregnant women remains low. We investigated whether unvaccinated pregnant women were clustered geographically and determined factors associated with failure to vaccinate using spatial and multivariate logistic regression analyses. Pregnant women who were members of Kaiser Permanente Northern California in 2015 or 2016 were included in the study. More than half (53%) of the 77,607 included pregnant women were unvaccinated. Spatial analysis identified 5 clusters with a high prevalence of unvaccinated pregnant women. The proportion of unvaccinated women ranged from 57% to 75% within clusters as compared with 51% outside clusters. In covariate-adjusted analyses, residence in a cluster was associated with a 41% increase in the odds of being unvaccinated (odds ratio (OR) = 1.41, 95% confidence interval (CI): 1.36, 1.46). The odds of being unvaccinated were greater for Black women (OR = 1.58, 95% CI: 1.49, 1.69), Hispanic women (OR = 1.15, 95% CI: 1.05, 1.25), women with subsidized health insurance (OR = 1.18, 95% CI: 1.11, 1.24), women with fewer than 5 prenatal-care visits (OR = 1.85, 95% CI: 1.60, 2.16), and neighborhoods with a high deprivation index (fourth quartile vs. first: OR = 1.14, 95% CI: 1.07, 1.21). In conclusion, unvaccinated pregnant women were clustered geographically and by key sociodemographic factors. These findings suggest that interventions to increase influenza vaccine coverage among pregnant women are needed, particularly in vulnerable populations.

Web-Based Tailored Messaging to Increase Vaccination: A Randomized Clinical Trial

BACKGROUND

To increase vaccine acceptance, we created a Web-based the "Vaccines and Your Baby" intervention (VAYB) that provided new parents with vaccine information messages tailored to vaccine beliefs and values. We evaluated the effectiveness of the VAYB by comparing timely uptake of infant vaccines to an untailored version of the intervention (UT) or usual care intervention (UC) only.

METHODS

Between April 2016 and June 2019, we conducted a randomized clinical trial. Pregnant women and new parents were randomly assigned to the VAYB, UT, or UC arms. In the VAYB and UT arms, participants were exposed to interventions at 4 time points from pregnancy until their child was 15 months of age. The primary outcome was up-to-date status for recommended vaccines from birth to 200 days of age. A modified intent-to-treat analysis was conducted. Data were analyzed with logistic regression to generate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

We enrolled 824 participants (276 VAYB, 274 UT, 274 UC), 143 (17.4%) of whom were lost to follow-up. The up-to-date rates in the VAYB, UT, and UC arms were 91.44%, 92.86%, and 92.31%, respectively. Infants in the VAYB arm were not more likely to be up to date than infants in the UC arm (OR = 0.89; 95% CI, 0.45-1.76) or in the UT arm (OR = 0.82; 95% CI, 0.42-1.63). The odds of being up to date did not differ between UT and UC arms (OR = 1.08; 95% CI, 0.54-2.18).

CONCLUSIONS

Delivering Web-based vaccine messages tailored to parents' vaccine attitudes and values did not positively impact the timely uptake of infant vaccines.

Mumps Outbreaks in Vaccinated Populations-Is It Time to Re-assess the Clinical Efficacy of Vaccines?

History illustrates the remarkable public health impact of mass vaccination, by dramatically improving life expectancy and reducing the burden of infectious diseases and co-morbidities worldwide. It has been perceived that if an individual adhered to the MMR vaccine schedule that immunity to mumps virus (MuV) would be lifelong. Recent mumps outbreaks in individuals who had received two doses of the Measles Mumps Rubella (MMR) vaccine has challenged the efficacy of the MMR vaccine. However, clinical symptoms, complications, viral shedding and transmission associated with mumps infection has been shown to be reduced in vaccinated individuals, demonstrating a benefit of this vaccine. Therefore, the question of what constitutes a good mumps vaccine and how its impact is assessed in this modern era remains to be addressed. Epidemiology of the individuals most affected by the outbreaks (predominantly young adults) and variance in the circulating MuV genotype have been well-described alluding to a collection of influences such as vaccine hesitancy, heterogeneous vaccine uptake, primary, and/or secondary vaccine failures. This review aims to discuss in detail the interplay of factors thought to be contributing to the current mumps outbreaks seen in highly vaccinated populations. In addition, how mumps diagnoses has progressed and impacted the understanding of mumps infection since a mumps vaccine was first developed, the limitations of current laboratory tests in confirming protection in vaccinated individuals and how vaccine effectiveness is quantified are also considered. By highlighting knowledge gaps within this area, this state-of-the-art review proposes a change of perspective regarding the impact of a vaccine in a highly vaccinated population from a clinical, diagnostic and public perspective, highlighting a need for a paradigm shift on what is considered vaccine immunity.

Policies Among US Pediatricians for Dismissing Patients for Delaying or Refusing Vaccination

This survey study assesses US pediatrician practices and office policies in response to parents who either refuse primary vaccinations or request to spread out individual vaccines in the primary series.

Evaluation of a Vaccine-Communication Tool for Physicians

OBJECTIVES

To evaluate a Kaiser Permanente Northern California physician training tool entitled "Effective Communication without Confrontation" aimed at improving communication with vaccine-hesitant parents, building trust, and alleviating physician stress surrounding vaccination visits.

STUDY DESIGN

Trainings were held May to July 2015. Pre- and post-training surveys assessed physician comfort and perceived effectiveness in communicating with vaccine-hesitant parents. We measured vaccination coverage at the 2-, 4-, and 6-month well-child visits, and days undervaccinated at 9 months of age. We compared vaccination rates before and after the training.

RESULTS

Of 415 physicians who received training, 249 completed post-training surveys. Physicians reported that the training helped them feel "much more or more" comfortable talking with parents who are unsure (72.3%), want to delay (73.9%), or refuse (63.5%) vaccinations and "much more or more" effective at persuading parents who are unsure (67.5%) or want to delay vaccinations (61.4%). They reported feeling "the same or less" effective persuading parents who refuse vaccinations (66.3%). Vaccine coverage remained unchanged and high from before to after the training (95%-96%), as did parent satisfaction with his or her child's provider (4.73/5.00).

CONCLUSIONS

The Effective Communication without Confrontation training did not increase vaccine coverage, but did improve physicians' comfort and perceived effectiveness communicating with most vaccine-hesitant parents and may help to ease potentially stressful vaccination visits.

'Presumptively Initiating Vaccines and Optimizing Talk with Motivational Interviewing' (PIVOT with MI) trial: a protocol for a cluster randomised controlled trial of a clinician vaccine communication intervention

INTRODUCTION

A key contributor to underimmunisation is parental refusal or delay of vaccines due to vaccine concerns. Many clinicians lack confidence in communicating with vaccine-hesitant parents (VHP) and perceive that their discussions will do little to change parents' minds. Improving clinician communication with VHPs is critical to increasing childhood vaccine uptake.

METHODS AND ANALYSIS

We describe the protocol for a cluster randomised controlled trial to test the impact of a novel, multifaceted clinician vaccine communication strategy on child immunisation status. The trial will be conducted in 24 primary care practices in two US states (Washington and Colorado). The strategy is called Presumptively Initiating Vaccines and Optimizing Talk with Motivational Interviewing (PIVOT with MI), and involves clinicians initiating the vaccine conversation with all parents of young children using the presumptive format, and among those parents who resist vaccines, pivoting to using MI. Our primary outcome is the immunisation status of children of VHPs at 19 months, 0 day of age expressed as the percentage of days underimmunised from birth to 19 months for 22 doses of eight vaccines recommended during this interval. Secondary outcomes include clinician experience communicating with VHPs, parent visit experience and clinician adherence to the PIVOT with MI communication strategy.

ETHICS AND DISSEMINATION

This study is approved by the following institutional review boards: Colorado Multiple Institutional Review Board, Washington State Institutional Review Board and Swedish Health Services Institutional Review Board. Results will be disseminated through peer-reviewed manuscripts and conference presentations.

TRIAL REGISTRATION NUMBER

NCT03885232.

Analysis of health outcomes in vaccinated and unvaccinated children: Developmental delays, asthma, ear infections and gastrointestinal disorders

Objective:

The aim of this study was to compare the health of vaccinated versus unvaccinated pediatric populations.

Methods:

Using data from three medical practices in the United States with children born between November 2005 and June 2015, vaccinated children were compared to unvaccinated children during the first year of life for later incidence of developmental delays, asthma, ear infections and gastrointestinal disorders. All diagnoses utilized International Classification of Diseases–9 and International Classification of Diseases–10 codes through medical chart review. Subjects were a minimum of 3 years of age, stratified based on medical practice, year of birth and gender and compared using a logistic regression model.

Results:

Vaccination before 1 year of age was associated with increased odds of developmental delays (OR = 2.18, 95% CI 1.47–3.24), asthma (OR = 4.49, 95% CI 2.04–9.88) and ear infections (OR = 2.13, 95% CI 1.63–2.78). In a quartile analysis, subjects were grouped by number of vaccine doses received in the first year of life. Higher odds ratios were observed in Quartiles 3 and 4 (where more vaccine doses were received) for all four health conditions considered, as compared to Quartile 1. In a temporal analysis, developmental delays showed a linear increase as the age cut-offs increased from 6 to 12 to 18 to 24 months of age (ORs = 1.95, 2.18, 2.92 and 3.51, respectively). Slightly higher ORs were also observed for all four health conditions when time permitted for a diagnosis was extended from ⩾ 3 years of age to ⩾ 5 years of age.

Conclusion:

In this study, which only allowed for the calculation of unadjusted observational associations, higher ORs were observed within the vaccinated versus unvaccinated group for developmental delays, asthma and ear infections. Further study is necessary to understand the full spectrum of health effects associated with childhood vaccination.

Opinions and Knowledge of Parents Regarding Preventive Vaccinations of Children and Causes of Reluctance toward Preventive Vaccinations

Background: Despite the stability of global vaccination coverage, over 19 million children worldwide do not currently receive basic vaccines. Over the past several years, there has been a dramatic drop in the number of vaccinated children worldwide. The implementation of the vaccination program and the scope of protection depend on the parents or legal guardians, who decide whether to vaccinate their child or not. Studies were conducted to assess parents’ knowledge, attitudes, and beliefs about vaccines, as well as the role of healthcare providers in parents’ decisions. Methods: A population survey was conducted in 2018–2019. Parents or legal guardians of the children were invited to participate in the study during their visits to the clinic for healthy or sick children. The method used in the research was a diagnostic survey. Results: According to the conducted research, men and women constituted 45% and 55% of participants, respectively. The average age of men was 44, while, for women, it was 41. Internal research showed that as much as 71% of parents declared the need for vaccination, although 41% of parents vaccinated their children according to the vaccination calendar. The most frequently mentioned concerns included the possibility of adverse vaccination reactions (22%), the occurrence of autism (7%), and child death (6%). General practitioners had, by far, the greatest impact on the use of protective vaccination in children (73% women and 80% men), although there were cases of discouraging the performance of compulsory vaccinations (41%), and mentioning a doctor (38%) or nurse (3%). Conclusions: Modifiable determinants of the negative attitude toward vaccinations are caused mainly by the lack of knowledge. These obstacles in vaccinations can be overcome by improving health education in terms of the vaccination program.

A qualitative study examining pediatric clinicians' perceptions of delayed vaccine schedules

OBJECTIVE

To explore pediatric clinicians' attitudes, beliefs, and perceived social norms about the impact of delayed vaccine schedules on the clinical management of their patients.

METHODS

We conducted 30 semi-structured qualitative interviews with academic (Infectious Diseases, Emergency Medicine) and community pediatric clinicians (General Pediatrics) to explore clinicians' perspectives on how delayed schedules influence their clinical management of patients. The interview guide was based on the Theory of Planned Behavior. We analyzed interview transcripts using both an inductive and deductive thematic approach.

RESULTS

The pediatric clinicians in our study overwhelmingly supported the recommended schedule, sought guidance on approaches to navigating conversations with vaccine hesitant families, and desired more evidence to effectively promote on-time vaccination. Clinicians described how delayed schedules have consequences for sick children (e.g., increased antibiotics, laboratory tests, emergency department visits) and healthy children (e.g., increased vaccine visits, out-of-pocket costs, fears among children receiving frequent shots). Clinicians stated that delayed schedules also negatively impact pediatric practices (e.g., increased time counseling patients, staff burden, clogged clinic space, unpredictable vaccine utilization, costs).

CONCLUSIONS

Pediatric clinicians perceive that delayed vaccine schedules negatively affect patients, pediatric practices, the healthcare system, and society. Future research should quantify the consequences of delayed schedules and identify strategies that promote vaccine adherence. Results from future studies can better support clinician-parent conversations about vaccine hesitancy, guide decision-makers about practice-level approaches to vaccine schedules, and advise payors and policymakers regarding vaccine-related policies.

Association Between Rotavirus Vaccination and Type 1 Diabetes in Children

IMPORTANCE

Because rotavirus infection is a hypothesized risk factor for type 1 diabetes, live attenuated rotavirus vaccination could increase or decrease the risk of type 1 diabetes in children.

OBJECTIVE

To examine whether there is an association between rotavirus vaccination and incidence of type 1 diabetes in children aged 8 months to 11 years.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective cohort study of 386 937 children born between January 1, 2006, and December 31, 2014, was conducted in 7 US health care organizations of the Vaccine Safety Datalink. Eligible children were followed up until a diagnosis of type 1 diabetes, disenrollment, or December 31, 2017.

EXPOSURES

Rotavirus vaccination for children aged 2 to 8 months. Three exposure groups were created. The first group included children who received all recommended doses of rotavirus vaccine by 8 months of age (fully exposed to rotavirus vaccination). The second group had received some, but not all, recommended rotavirus vaccines (partially exposed to rotavirus vaccination). The third group did not receive any doses of rotavirus vaccines (unexposed to rotavirus vaccination).

MAIN OUTCOMES AND MEASURES

Incidence of type 1 diabetes among children aged 8 months to 11 years. Type 1 diabetes was identified by International Classification of Diseases codes: 250.x1, 250.x3, or E10.xx in the outpatient setting. Cox proportional hazards regression models were used to analyze time to type 1 diabetes incidence from 8 months to 11 years. Hazard ratios and 95% CIs were calculated. Models were adjusted for sex, race/ethnicity, birth year, mother's age, birth weight, gestational age, number of well-child visits, and Vaccine Safety Datalink site.

RESULTS

In a cohort of 386 937 children (51.1% boys and 41.9% non-Hispanic white), 360 169 (93.1%) were fully exposed to rotavirus vaccination, 15 765 (4.1%) were partially exposed to rotavirus vaccination, and 11 003 (2.8%) were unexposed to rotavirus vaccination. Children were followed up a median of 5.4 years (interquartile range, 3.8-7.8 years). The total person-time follow-up in the cohort was 2 253 879 years. There were 464 cases of type 1 diabetes in the cohort, with an incidence rate of 20.6 cases per 100 000 person-years. Compared with children unexposed to rotavirus vaccination, the adjusted hazard ratio was 1.03 (95% CI, 0.62-1.72) for children fully exposed to rotavirus vaccination and 1.50 (95% CI, 0.81-2.77) for children partially exposed to rotavirus vaccination.

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that rotavirus vaccination does not appear to be associated with type 1 diabetes in children.

A Values-Tailored Web-Based Intervention for New Mothers to Increase Infant Vaccine Uptake: Development and Qualitative Study

BACKGROUND

Vaccine hesitancy among parents leads to childhood undervaccination and outbreaks of vaccine-preventable disease. As the reasons for vaccine hesitancy are diverse, there is often not enough time during regular clinical visits for medical providers to adequately address all the concerns that parents have. Providing individually tailored vaccine information via the internet before a clinical visit may be a good mechanism for effectively allaying parents' vaccination concerns while also being time efficient. Including tailoring based on values is a promising, but untested, approach to message creation.

OBJECTIVE

This study aimed to describe the process by which we developed a Web-based intervention that is being used in an ongoing randomized controlled trial aimed at improving the timeliness of infant vaccination by reducing parental vaccine hesitancy.

METHODS

Development of the intervention incorporated evidence-based health behavior theories. A series of interviews, surveys, and feedback sessions were used to iteratively develop the intervention in collaboration with vaccination experts and potential end users.

RESULTS

In all, 41 specific content areas were identified to be included in the intervention. User feedback elucidated preferences for specific design elements to be incorporated throughout the website. The tile-based architecture chosen for the website was perceived as easy to use. Creating messages that were two-sided was generally preferred over other message formats. Quantitative surveys identified associations between specific vaccine values and vaccination beliefs, suggesting that values tailoring should vary, depending on the specific belief being endorsed.

CONCLUSIONS

Using health behavior theories, qualitative and quantitative data, and significant expert and end user input, we created a novel, Web-based intervention to improve infant vaccination timeliness. The intervention is based on tailoring messages according to each individual's values and beliefs. This intervention is currently being tested in a controlled randomized clinical trial.

Vaccination Discussion among Parents on Social Media: A Content Analysis of Comments on Parenting Blogs

Despite the effectiveness of vaccines, parents are increasingly opting for non-medical exemption. For health advice on such topics, many parents are now more likely to look to online communities than rely on medical expertise. There is scant literature outlining how parents contribute to online discussion of vaccination. The purpose of this study was to analyze parent vaccination opinions expressed online. Using a codebook adapted from previous research, content analysis was conducted to evaluate comments on parenting blog posts related to vaccination. Variables included stance, argument rhetoric, and accuracy of information. Comments recognized as aggressive or accusatory were recorded into an "attack" category. Descriptive statistics were used to assess trends in comment content. Nine blogs were included, from which 244 comments were analyzed. The most common argument rhetoric was providing, requesting, or evaluating source credibility for both pro- and anti-vaccine comments (24% and 36%). 25% of comments were considered inaccurate health information; 27% fell into the "attack" category, of which 60% were pro-vaccination. The high percentage of "attack" comments and inaccurate information is evidence that blog comments may not be reliable for information-seeking parents. Clinicians should use this data to understand anti-vaccination arguments in efforts to improve vaccine communication.

Vaccination Status and Adherence to Quality Measures for Acute Respiratory Tract Illnesses

OBJECTIVES

To assess the relationship between vaccination status and clinician adherence to quality measures for children with acute respiratory tract illnesses.

METHODS

We conducted a multicenter prospective cohort study of children aged 0 to 16 years who presented with 1 of 4 acute respiratory tract illness diagnoses (community-acquired pneumonia, croup, asthma, and bronchiolitis) between July 2014 and June 2016. The predictor variable was provider-documented up-to-date (UTD) vaccination status. Our primary outcome was clinician adherence to quality measures by using the validated Pediatric Respiratory Illness Measurement System (PRIMES). Across all conditions, we examined overall PRIMES composite scores and overuse (including indicators for care that should not be provided, eg, C-reactive protein testing in community-acquired pneumonia) and underuse (including indicators for care that should be provided, eg, dexamethasone in croup) composite subscores. We examined differences in length of stay, costs, and readmissions by vaccination status using adjusted linear and logistic regression models.

RESULTS

Of the 2302 participants included in the analysis, 92% were documented as UTD. The adjusted mean difference in overall PRIMES scores by UTD status was not significant (adjusted mean difference -0.3; 95% confidence interval: -1.9 to 1.3), whereas the adjusted mean difference was significant for both overuse (-4.6; 95% confidence interval: -7.5 to -1.6) and underuse (2.8; 95% confidence interval: 0.9 to 4.8) composite subscores. There were no significant adjusted differences in mean length of stay, cost, and readmissions by vaccination status.

CONCLUSIONS

We identified lower adherence to overuse quality indicators and higher adherence to underuse quality indicators for children not UTD, which suggests that clinicians "do more" for hospitalized children who are not UTD.

Order of Live and Inactivated Vaccines and Risk of Non-vaccine-targeted Infections in US Children 11-23 Months of Age

BACKGROUND

Some findings from observational studies have suggested that recent receipt of live vaccines may be associated with decreased non-vaccine-targeted infection risk and mortality. Our objective was to estimate risk of non-vaccine-targeted infections based on most recent vaccine type (live vaccines only, inactivated vaccines only or both concurrently) received in US children 11-23 months of age.

METHODS

We conducted a retrospective cohort study within the Vaccine Safety Datalink. We examined electronic health record and immunization data from children born in 2003-2013 who received 3 diphtheria-tetanus-acellular pertussis vaccines before their first birthday. We modeled vaccine type as a time-varying exposure and estimated risk of non-vaccine-targeted infections identified in emergency department and inpatient settings, adjusting for multiple confounders.

RESULTS

Among 428,608 children, 48.9% were female, 4.9% had ≥1 immunization visit with live vaccines only and 10.3% had a non-vaccine-targeted infection. In males, lower risk of non-vaccine-targeted infections was observed following last receipt of live vaccines only or live and inactivated vaccines concurrently as compared with last receipt of inactivated vaccines only [live vaccines-only adjusted hazard ratio (aHR) = 0.83, 95% confidence interval (CI): 0.72-0.94; live and inactivated vaccines concurrently aHR: 0.91, 95% CI: 0.88-0.94]. Among females, last receipt of live and inactivated vaccines concurrently was significantly associated with non-vaccine-targeted infection risk (aHR = 0.94, 95% CI: 0.91-0.97 vs. last receipt of inactivated vaccines only).

CONCLUSIONS

We observed modest associations between live vaccine receipt and non-vaccine-targeted infections. In this observational study, multiple factors, including healthcare-seeking behavior, may have influenced results.