Vaccination Coverage for Selected Vaccines and Exemption Rates Among Children in Kindergarten - United States, 2017-18 School Year

Predicting Measles Outbreaks in the United States: Evaluation of Machine Learning Approaches (Preprint)

BACKGROUND

Measles, a highly contagious viral infection, is resurging in the United States, driven by international importation and declining domestic vaccination coverage. Despite this resurgence, measles outbreaks are still rare events that are difficult to predict. Improved methods to predict outbreaks at the county level would facilitate the optimal allocation of public health resources.

OBJECTIVE

We aimed to validate and compare extreme gradient boosting (XGBoost) and logistic regression, 2 supervised learning approaches, to predict the US counties most likely to experience measles cases. We also aimed to assess the performance of hybrid versions of these models that incorporated additional predictors generated by 2 clustering algorithms, hierarchical density-based spatial clustering of applications with noise (HDBSCAN) and unsupervised random forest (uRF).

METHODS

We constructed a supervised machine learning model based on XGBoost and unsupervised models based on HDBSCAN and uRF. The unsupervised models were used to investigate clustering patterns among counties with measles outbreaks; these clustering data were also incorporated into hybrid XGBoost models as additional input variables. The machine learning models were then compared to logistic regression models with and without input from the unsupervised models.

RESULTS

Both HDBSCAN and uRF identified clusters that included a high percentage of counties with measles outbreaks. XGBoost and XGBoost hybrid models outperformed logistic regression and logistic regression hybrid models, with the area under the receiver operating curve values of 0.920-0.926 versus 0.900-0.908, the area under the precision-recall curve values of 0.522-0.532 versus 0.485-0.513, and F₂ scores of 0.595-0.601 versus 0.385-0.426. Logistic regression or logistic regression hybrid models had higher sensitivity than XGBoost or XGBoost hybrid models (0.837-0.857 vs 0.704-0.735) but a lower positive predictive value (0.122-0.141 vs 0.340-0.367) and specificity (0.793-0.821 vs 0.952-0.958). The hybrid versions of the logistic regression and XGBoost models had slightly higher areas under the precision-recall curve, specificity, and positive predictive values than the respective models that did not include any unsupervised features.

CONCLUSIONS

XGBoost provided more accurate predictions of measles cases at the county level compared with logistic regression. The threshold of prediction in this model can be adjusted to align with each county's resources, priorities, and risk for measles. While clustering pattern data from unsupervised machine learning approaches improved some aspects of model performance in this imbalanced data set, the optimal approach for the integration of such approaches with supervised machine learning models requires further investigation.

Understanding the Role of Psychosocial Factors in Pakistani Parents' Hesitancy to Vaccinate Their Kids: The Mediating Role of Knowledge and Mistrust of Science about the COVID-19 Vaccine

Vaccination is a vital component in the battle against outbreaks of infectious diseases. Recognizing parents' reluctance to vaccinate their children is even more critical now, given the ongoing threat of a COVID-19 pandemic. Conspiracy theories, vaccination safety concerns, parental efficacy and risk perception, and a lack of confidence in science all influence intention. To investigate how these variables interact with vaccination behavior against COVID-19, we developed a model with psychosocial factors serving as the predictor and mistrust in science and vaccine knowledge serving as the mediator. In order to validate the model, the parents' intentions regarding their children's vaccination with COVID-19 were used. The study included 454 Pakistani parents who completed an online questionnaire assessing their intention to vaccinate their children. We analyzed the data using structural equation modeling (SEM). A significant level of vaccine hesitation is due to belief in vaccine conspiracy theories, and vaccine safety concerns were investigated. A surprising correlation exists between risk perception and vaccination intentions, followed by parental self-efficacy. It is significant to note that vaccine knowledge mediated conspiracy beliefs, risk perceptions, and intentions fully but partially mediated parental self-efficacy. Conspiracy theories were mediated by a mistrust in science, while perceptions of risk and vaccine safety were partially mediated. The findings of this research were used to develop sensible policy reforms and public health campaigns to encourage vaccination against both common infections such as measles, human papillomaviruses, or pertussis, and novel diseases such as COVID-19.

Impact of universal varicella vaccination on the use and cost of antibiotics and antivirals for varicella management in the United States

Background

Our objective was to estimate the impact of universal varicella vaccination (UVV) on the use and costs of antibiotics and antivirals for the management of varicella among children in the United States (US).

Methods

A decision tree model of varicella vaccination, infections and treatment decisions was developed. Results were extrapolated to the 2017 population of 73.5 million US children. Model parameters were populated from published sources. Treatment decisions were derived from a survey of health care professionals’ recommendations. The base case modelled current vaccination coverage rates in the US with additional scenarios analyses conducted for 0%, 20%, and 80% coverage and did not account for herd immunity benefits.

Results

Our model estimated that 551,434 varicella cases occurred annually among children ≤ 18 years in 2017. Antivirals or antibiotics were prescribed in 23.9% of cases, with unvaccinated children receiving the majority for base case. The annual cost for varicella antiviral and antibiotic treatment was approximately $14 million ($26 per case), with cases with no complications accounting for $12 million. Compared with the no vaccination scenario, the current vaccination rates resulted in savings of $181 million (94.7%) for antivirals and $78 million (95.0%) for antibiotics annually. Scenario analyses showed that higher vaccination coverage (from 0% to 80%) resulted in reduced annual expenditures for antivirals (from $191 million to $41 million), and antibiotics ($82 million to $17 million).

Conclusions

UVV was associated with significant reductions in the use of antibiotics and antivirals and their associated costs in the US. Higher vaccination coverage was associated with lower use and costs of antibiotics and antivirals for varicella management.

Improving Immunization Rates During the 2019 Measles Outbreak

In 2019, there were multiple outbreaks of measles in the United States. In the context of the public awareness of these outbreaks, we performed an intervention with the intent to improve the rate of measles immunization in our pediatric population. Pediatric patients that were lacking adequate measles immunization were identified by electronic medical record (EMR) survey. Charts were reviewed and updated if records were found to be incomplete. Parents of the remaining children were sent a letter, personally signed by the child’s primary care provider, encouraging measles immunization. A measles fact sheet, produced by the United States Center for Disease Control, was also included with the letter. There were 44 patients in the study group whose parents received a letter and measles fact sheet. As a result, 5 of these children were brought in for a measles, mumps, and rubella (MMR) immunization. The 44 patients whose parents received a letter included 20 patients whose parents had previously expressed intent to not vaccinate their children as documented in the EMR. None of these children received an MMR immunization. Although small in scope, this project provides a glimpse into the importance of personal provider guidance to parents who are inclined to immunize their children. Unfortunately, it also demonstrated that provider advice did not change the opinions of parents who had already taken a stance against vaccination, even in the context of an urgent public health situation that had garnered widespread coverage in the lay press and social media.

Immunization practices and risk of anaphylaxis: a current update, comprehensive of COVID-19 vaccination data

PURPOSE OF REVIEW

This review aims to provide an updated report in regards to the correlation between vaccines and anaphylaxis and the related risk in the population.

RECENT FINDINGS

Initial reports showed higher incidence of anaphylaxis following messenger RNA COVID-19 vaccines compared with 'routine' vaccinations, likely influenced by the great attention paid to these 'new' vaccines. However, anaphylaxis has still to be considered quite rare and its incidence will be systematically reconsidered in the light of additional data collected.

SUMMARY

Adverse reactions to vaccines are commonly reported but most of them are nonspecific mild events, whereas vaccine-related anaphylaxis is considered a rare event, with an incidence rate equal to 1.3 cases per million vaccine doses administered. As anaphylaxis reports usually start to be reported to passive pharmacovigilance during postmarketing surveillance, the first data are used to be influenced by under- and over-reporting and lack of denominators and following studies are needed to confirm the causal relationship. This might create an initial overcautiously approach to new immunization practices but, being anaphylaxis a potential life-threatening event, every suspected contraindication has to be deepened to maximize effectiveness and safety profile and constantly redefined not to exclude an overestimated population group who could receive the vaccine uneventfully.

COVID-19 Vaccine Discourse on Twitter: A Content Analysis of Persuasion Techniques, Sentiment and Mis/Disinformation

This research aims to understand the persuasion techniques used in Twitter posts about COVID-19 vaccines by the different vaccine sentiments (i.e., Pro-Vaccine, Anti-Vaccine, and Neutral) using the Elaboration Likelihood Model, Social judgment Theory, and the Extended Parallel Process Model as theoretical frameworks. A content analysis was conducted on a data set of 1,000 Twitter posts. The corpus of Tweets was examined using the persuasion frameworks; tweets that were identified as emanating from bots were further examined. Results found Anti-Vaccine messages predominantly used Anecdotal stories, Humor/Sarcasm, and Celebrity figures as persuasion techniques, while Pro-Vaccine messages primarily used Information, Celebrity figures, and Participation. Results also showed the Anti-Vaccine messages primarily focused on values related to the categories of Safety, Political/Conspiracy Theories, and Choice. Finally, results revealed Anti-Vaccine messages primarily used Perceived Severity and Perceived Susceptibility, which are fear appeal elements. The findings for messages by bots were comparable to the messages in the larger corpus of tweets. Based on the findings, a response framework-Health Information Persuasion Exploration (HIPE)-is proposed to address mis/disinformation and Anti-Vaccine messaging. The results of this study and the HIPE framework can inform a national COVID-19 vaccine health campaign to increase vaccine adoption.

School-level perceptions and enforcement of the elimination of nonmedical exemptions to vaccination in California

In 2015, California passed Senate Bill 277 eliminating all nonmedical exemptions to school vaccinations. We aimed to explore school-level modes of SB277 enforcement, characterize vaccination knowledge, attitudes, and beliefs of school officials, and identify whether school vaccination policies are associated with medical exemptions being granted. Surveys were mailed to a stratified random sample of 1,450 schools in California. School personnel (n = 752) reported their medical training, vaccination beliefs, enforcement of vaccination policies, and school rates of medical exemptions. Multiple logistic regression was used to assess whether school policies are associated with the likelihood of medical exemption requests being granted. Nurses were more likely than non-nurses to hold beliefs recognizing the importance of vaccination. A school where the survey respondent was a nurse was more likely to have granted a medical exemption request compared to a school where the respondent was not a nurse (OR 2.11, 95% CI 1.34-3.36). The training of school officials and school-level practices may impact the enforcement of medical exemptions. Equipping school officials as competent sources of vaccine information for concerned parents will be valuable in improving parental vaccine uptake.

Barriers to Pretransplant Immunization: A Qualitative Interview Study of Pediatric Solid Organ Transplant Stakeholders

OBJECTIVES

To describe the experiences and beliefs of pediatric transplant stakeholders regarding factors that contribute to low pretransplant immunization rates.

STUDY DESIGN

Semistructured interviews were conducted with transplant team members (hepatologists, cardiologists, nephrologists, transplant nurse coordinators, and transplant infectious diseases physicians), primary care physicians, and parents of heart, liver, and kidney transplant recipients at 3 geographically diverse large pediatric transplant centers in the US. Interviews were conducted between July 2017 and February 2020 until thematic saturation was reached within each stakeholder subgroup. Content analysis methodology was used to identify themes.

RESULTS

Stakeholders participated in 30- to 60-minute interviews (16 transplant subspecialists, 3 transplant infectious diseases physicians, 11 transplant nurse coordinators, 12 primary care physicians, and 40 parents). Five central themes emerged: (1) gaps in knowledge about timing and safety of pretransplant immunizations, (2) lack of communication, coordination, and follow-up between team members regarding immunizations, (3) lack of centralized immunization records, (4) subspecialty clinic functioning as the medical home for transplant candidates but unable to provide all needed immunizations, and (5) differences between organ type in prioritization and completion of pretransplant immunization.

CONCLUSIONS

There are multiple factors that contribute to low immunization rates among pediatric transplant candidates. New tools are needed to overcome these barriers and increase immunization rates in transplant candidates.

The Importance of Prioritizing Pre and Posttransplant Immunizations in an Era of Vaccine Refusal and Epidemic Outbreaks

Vaccine-preventable infections are occurring at epidemic rates both nationally and internationally. At the same time, rates of vaccine hesitancy and refusal are increasing across the country leading to decreased herd immunity. For immunosuppressed transplant recipients, this situation poses great risk. Currently, 1 in 6 pediatric solid organ transplant recipients is hospitalized with a vaccine-preventable infection in the first 5 years posttransplant. For many recipients, these infections result in significant morbidity, mortality, and increased hospitalization costs. Surprisingly, despite this risk many transplant recipients are not up-to-date on age appropriate immunizations at the time of transplant and thereafter. As a transplant community, we must prioritize immunizations in both pre and posttransplant care. Research is needed to understand how to monitor immune response to vaccines in immunosuppressed patients and when to optimally immunize patients posttransplant. Finally, recommendations about administration of live vaccines posttransplant may need to be reevaluated in the setting of measles outbreaks and decreased herd immunity.

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.

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.

Communicating About Immunizations

A significant minority of patients and parents are vaccine hesitant, defined as having the desire to delay or defer immunizations despite easy access to vaccines. Vaccine hesitancy exists along a spectrum, from patients who are concerned but willing to accept the recommended vaccine schedule to those who wish to use a delayed schedule to those who refuse vaccines altogether. A strong recommendation in favor of a vaccine is the most important reason a patient or parent accepts the immunization. Structural changes, such as removing personal and religious exemptions for vaccines required for attending school, are effective tools in increasing vaccination rates.

Influenza vaccination among U.S. pediatric patients receiving care from federally funded health centers

INTRODUCTION

During the 2018-2019 influenza season, vaccination coverage among U.S. children was 62.6%. The purpose of this study was to estimate the prevalence of influenza vaccinations among pediatric patients seen in U.S. health centers, and to explore potential disparities in vaccination coverage among subpopulations. Funded by the Health Resources and Services Administration (HRSA) within the U.S. Department of Health and Human Services, these health centers provide primary and preventive care to underserved and vulnerable individuals and families in order to reduce health disparities based on economic, geographic, or cultural barriers.

METHODS

Cross-sectional data, analyzed in 2019, came from the most recent waves of the Health Center Patient Survey (2009, 2014). The sample consisted of children ages 2-17 years receiving care from HRSA-funded health centers. The outcome of interest was self- or parent-reported receipt of influenza vaccine in the past year. Multivariable logistic regression was used to estimate the adjusted prevalence rate ratios for the association between demographic characteristics (age, sex, race/ethnicity, poverty level, urban/rural residence, geographic region), health-related variables (receipt of well-child check-up, asthma diagnosis), and influenza vaccination.

RESULTS

Influenza vaccination coverage among pediatric health center patients increased from 46.6% in 2009 to 67.8% in 2014. In the adjusted model for 2014, there were few statistically significant differences in vaccination coverage among subpopulation groups, however American Indian/Alaska Native children had 31% increased vaccination coverage compared with non-Hispanic White children (aPRR: 1.31, 95% CI: 1.02-1.60) and children living in the South had 26% decreased vaccination coverage compared with those living in the Northeast (aPRR: 0.74, 95% CI: 0.54-0.93).

CONCLUSIONS

Influenza vaccination coverage among pediatric health center patients in 2014 exceeded the national average (as of 2018-2019), and few differences were found among at-risk subpopulations. HRSA-funded health centers are well-positioned to further increase the vaccination rate among children living in underserved communities.

Centers for Disease Control and Prevention's School Vaccination Assessment: Collaboration With US State, Local, and Territorial Immunization Programs, 2012-2018

Objectives. To describe the ongoing collaboration of the Centers for Disease Control and Prevention's (CDC's) school vaccination assessment with state, local, and territorial immunization programs to provide data to monitor school entry vaccination.Methods. Departments of health and education partner to collect data from public school, private school, and homeschooled kindergartners in the 50 US states, the District of Columbia, 2 cities, and the US territories. Immunization programs submit vaccination coverage and exemption data to the CDC, and the CDC reports these data annually via multiple sources.Results. Among the 50 states and the District of Columbia, the number of programs using a census for vaccination coverage data increased from 39 to 41 during the school years 2012-2013 to 2017-2018 (which for most states was August or September through May or June), and the number using a census to collect exemption data increased from 40 to 46. The number of states that reported sharing their local-level vaccination coverage data online increased from 11 in 2012-2013 to 31 in 2017-2018.Conclusions. Coverage data can be used to address undervaccination among kindergartners to work with communities and schools that are susceptible to vaccine-preventable diseases. As more states publish local-level data online, access to improved data provides the public more valuable information.

Modelling anti-vaccine sentiment as a cultural pathogen

Culturally transmitted traits that have deleterious effects on health-related traits can be regarded as cultural pathogens. A cultural pathogen can produce coupled dynamics with its associated health-related traits, so that understanding the dynamics of a health-related trait benefits from consideration of the dynamics of the associated cultural pathogen. Here, we treat anti-vaccine sentiment as a cultural pathogen, modelling its 'infection' dynamics with the infection dynamics of the associated vaccine-preventable disease. In a coupled susceptible-infected-resistant (SIR) model, consisting of an SIR model for the anti-vaccine sentiment and an interacting SIR model for the infectious disease, we explore the effect of anti-vaccine sentiment on disease dynamics. We find that disease endemism is contingent on the presence of the sentiment, and that presence of sentiment can enable diseases to become endemic when they would otherwise have disappeared. Furthermore, the sentiment dynamics can create situations in which the disease suddenly returns after a long period of dormancy. We study the effect of assortative sentiment-based interactions on the dynamics of sentiment and disease, identifying a tradeoff whereby assortative meeting aids the spread of a disease but hinders the spread of sentiment. Our results can contribute to finding strategies that reduce the impact of a cultural pathogen on disease, illuminating the value of cultural evolutionary modelling in the analysis of disease dynamics.

The state of vaccine safety science: systematic reviews of the evidence

This Review updates the scientific evidence assessing possible causal associations of adverse events following immunisation (AEFI) compiled in the 2012 report from the Institute of Medicine and the 2014 report from the Agency for Healthcare Research and Quality. For 12 of 46 AEFI examined, a causal relationship has been established with at least one vaccine currently routinely recommended to the general USA population: anaphylaxis, arthralgia or arthritis (mild, acute, and transient, not chronic), deltoid bursitis (when vaccine is administered improperly), disseminated varicella infection (in immune deficient individuals for whom the varicella vaccine is contraindicated), encephalitis, febrile seizures, Guillain-Barré syndrome, hepatitis (in immune deficient individuals for whom the varicella vaccine is contraindicated), herpes zoster, immune thrombocytopenic purpura, meningitis, and syncope. Other than mild acute and transient arthralgia or arthritis, which is very common in adult women after rubella vaccine, these adverse reactions are rare or very rare. Vaccines have an excellent safety profile overall and provide protection against infectious diseases to individuals and the general population.

Special Feature: Countering Vaccine Misinformation

Evidence consistently shows that vaccines are safe, effective, and cost-efficient. Yet preventable outbreaks of infectious diseases are occurring in the United States, leading to a strong public response and intense scrutiny of the antivaccine movement and its persistent spread of misinformation. Social media has been a major platform for such misinformation, and recent examinations have found that nurses are not exempt from engaging in antivaccine discourse.By practicing evidence-based care, addressing health literacy, and becoming involved in public health policy, nurses can be excellent advocates for immunization and may help prevent additional outbreaks of preventable diseases.

Getting Personal: How Childhood Vaccination Policies Shape the Landscape of Vaccine Exemptions

Background

State-mandated school entry immunization requirements in the United States play an important role in achieving high vaccine coverage, but variations in vaccine exemption policies result in a patchwork of vaccine coverage across the country.

Methods

In this study, we evaluate epidemiological effects and spatial variations in nonmedical exemption (NME) rates in the context of vaccine policies. We first analyze the correlation between NME rates and vaccine coverage for 3 significant childhood vaccinations. Furthermore, we assess the effects of policy changes in a subset of states, using a correlative approach at the state level and performing a clustering analysis at the county level.

Results

We find that higher rates of exemptions are associated with lower vaccination rates of school-aged children in all cases. In a subset of states where exemption policy has recently changed, we show that the effects on statewide NME rates vary widely and that decreases in NMEs can lead to an increase in other types of exemptions. Finally, our clustering analysis in California, Illinois, and Connecticut shows that policy changes affect the spatial distribution of NMEs.

Conclusions

Our work suggests that vaccination policies have significant impacts on patterns of herd immunity. Our findings can be used to develop evidence-based vaccine legislation.

Art of prevention: The importance of measles recognition and vaccination

Measles is a viral infection that has a characteristic pattern of prodromal symptoms followed by a rash. Previously considered an inevitable childhood condition, measles is known as the "first" classic childhood exanthem. For most children, measles was a one-time, short-term illness; however, some children developed complications that led to severe sequelae and death. The introduction of the measles vaccine dramatically decreased the number of cases, but the current trend against vaccination has caused outbreaks of the condition. We propose the implementation of the AAA approach (assume, advise, and answer) as a way for providers to directly encourage the administration of the vaccine and prevent future cases of measles.

Dismissal policies for vaccine refusal among US physicians: a literature review

Childhood vaccination is one of the greatest public health achievements of the 20th century, yet increasingly, parents question the safety of and need for vaccines. This has led to increased rates of vaccine delay and refusal and outbreaks of vaccine-preventable diseases. Physicians struggle with how to respond to families who refuse vaccines, as there are few known effective interventions to convince a family to vaccinate. In the United States, the practice of dismissing families for vaccine refusal appears to be increasing as a strategy for dealing with vaccine refusal. In this review, we review the literature surrounding this controversial practice, starting with the impact that vaccine-refusing families have on medical practices, followed by a review of dismissal policies of US physicians, and ending with a discussion of the ethics of this practice.

Repurposing the psoriasis drug Oxarol to an ointment adjuvant for the influenza vaccine

Aluminum precipitates have long been used as adjuvants for human vaccines, but there is a clear need for safer and more effective adjuvants. Here we report in a mouse model that the psoriasis drug Oxarol ointment is a highly effective vaccine adjuvant. By applying Oxarol ointment onto skin, humoral responses and germinal center (GC) reactions were augmented, and the treated mice were protected from death caused by influenza virus infection. Keratinocyte-specific vitamin D3 receptor (Vdr) gene expression was required for these responses through induction of the thymic stromal lymphopoietin (Tslp) gene. Experiments involving administration of recombinant TSLP or, conversely, anti-TSLP antibody demonstrated that TSLP plays a key role in the GC reactions. Furthermore, cell-type-specific Tslpr gene deletion or diphtheria toxin-mediated deletion of specific cell types revealed that CD11c+ cells excluding Langerhans cells were responsible for the Oxarol-mediated GC reactions. These results indicate that active vitamin D3 is able to enhance the humoral response via Tslp induction in the skin and serves as a new vaccine adjuvant.

Understanding the impact of state vaccination laws on exemption rates

PURPOSE OF REVIEW

This review summarizes the current state of school-entry vaccination requirements and related exemption policies in the United States and examines recent changes to these policies.

RECENT FINDINGS

With recent infectious disease outbreaks in the United States, there has been heightened awareness on unvaccinated individuals, and the state-level policies that allow individuals to be exempted from school-entry vaccination requirements. Between 2015 and 2017, there have been eleven states that have altered their policies regarding school-entry vaccination requirements and related reporting for which no formal evaluations have been published. One policy change during that period, California SB 277, which became law in 2016, reduced the nonmedical exemption and increased the childhood vaccination coverage rate in that state, though with some evidence of exemption replacement through the use of medical exemptions. Through September 2019, five additional state law changes have been enacted.

SUMMARY

The large number of heterogeneous changes to state-level policies for school-entry vaccination requirements in recent years need rigorous evaluation to identify best practices for balancing public health authority and parental autonomy while seeking to achieve the highest level of infectious disease prevention for children.

Clinical Practices for Measles-Mumps-Rubella Vaccination Among US Pediatric International Travelers

IMPORTANCE

The US population is experiencing a resurgence of measles, with more than 1000 cases during the first 6 months of 2019. Imported measles cases among returning international travelers are the source of most US measles outbreaks, and these importations can be reduced with pretravel measles-mumps-rubella (MMR) vaccination of pediatric travelers. Although it is estimated that children account for less than 10% of US international travelers, pediatric travelers account for 47% of all known measles importations.

OBJECTIVE

To examine clinical practice regarding MMR vaccination of pediatric international travelers and to identify reasons for nonvaccination of pediatric travelers identified as MMR eligible.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study of pediatric travelers (ages ≥6 months and <18 years) attending pretravel consultation at 29 sites associated with Global TravEpiNet (GTEN), a Centers for Disease Control and Prevention-supported consortium of clinical sites that provide pretravel consultations, was performed from January 1, 2009, through December 31, 2018.

MAIN OUTCOMES AND MEASURES

Measles-mumps-rubella vaccination among MMR vaccination-eligible pediatric travelers.

RESULTS

Of 14 602 pretravel consultations for pediatric international travelers, 2864 travelers (19.6%; 1475 [51.5%] males; 1389 [48.5%] females) were eligible to receive pretravel MMR vaccination at the time of the consultation: 365 of 398 infants aged 6 to 12 months (91.7%), 2161 of 3623 preschool-aged travelers aged 1 to 6 years (59.6%), and 338 of 10 581 school-aged travelers aged 6 to 18 years (3.2%). Of 2864 total MMR vaccination-eligible travelers, 1182 (41.3%) received the MMR vaccine and 1682 (58.7%) did not. The MMR vaccination-eligible travelers who did not receive vaccine included 161 of 365 infants (44.1%), 1222 of 2161 preschool-aged travelers (56.5%), and 299 of 338 school-aged travelers (88.5%). We observed a diversity of clinical practice at different GTEN sites. In multivariable analysis, MMR vaccination-eligible pediatric travelers were less likely to be vaccinated at the pretravel consultation if they were school-aged (model 1: odds ratio [OR], 0.32 [95% CI, 0.24-0.42; P < .001]; model 2: OR, 0.26 [95% CI, 0.14-0.47; P < .001]) or evaluated at specific GTEN sites (South: OR, 0.06 [95% CI, 0.01-0.52; P < .001]; West: OR, 0.10 [95% CI, 0.02-0.47; P < .001]). The most common reasons for nonvaccination were clinician decision not to administer MMR vaccine (621 of 1682 travelers [36.9%]) and guardian refusal (612 [36.4%]).

CONCLUSIONS AND RELEVANCE

Although most infant and preschool-aged travelers evaluated at GTEN sites were eligible for pretravel MMR vaccination, only 41.3% were vaccinated during pretravel consultation, mostly because of clinician decision or guardian refusal. Strategies may be needed to improve MMR vaccination among pediatric travelers and to reduce measles importations and outbreaks in the United States.

Resurgence of measles in the United States: how did we get here?

PURPOSE OF REVIEW

In September 2019, the United States was at risk of losing measles elimination status due to several large-scale outbreaks resulting in more than 1200 confirmed cases across 31 states. This resurgence caps approximately 10 years of increasing incidence, marked by a highly publicized outbreak in 2015 associated with Disneyland when an infected traveler from the Philippines unknowingly spread the virus to susceptible park visitors and the recently ended large outbreak in undervaccinated Orthodox Jewish communities in New York City and Rockland counties. This review highlights current literature elucidating factors associated with current trends in measles epidemiology in the United States, the public health implications of current measles outbreaks and a path forward for addressing challenges contributing to the resurgence of measles in the United States and globally.

RECENT FINDINGS AND SUMMARY

As the most highly transmissible vaccine preventable disease, measles is especially sensitive to changes in herd immunity, the impact of vaccine refusal and globalization. Results highlight the confluence of these factors in current outbreaks, provide tools to predict outbreak risk, demonstrate the growing impact of misinformation and evaluate the impact of policy approaches for outbreak control and prevention.

Impact of school-entry vaccination requirement changes on clinical practice implementation and adolescent vaccination rates in metropolitan Philadelphia

In 2017, Pennsylvania amended school-entry vaccination requirements including reduction of the provisional period from eight months to the first five days of school and requirement of meningococcal-conjugate vaccine (MCV4) for students entering 12th grade. This cross-sectional study evaluates the impact of these new requirements on clinical practice and vaccination rates among requirement-eligible adolescents within a large pediatric network in metropolitan Philadelphia. We surveyed providers from 24 pediatric primary care facilities across five Southeastern Pennsylvania counties to assess strategies for timely vaccination of children, facilitators and barriers to implementation of these strategies, and attitudes toward the new school vaccine requirements. Vaccination rates post-five-day grace period among eligible 12-18-year-old adolescents were calculated using aggregate electronic health record data and compared pre- and post-policy implementation (2016 vs. 2017) using two-sample tests of proportion. Overall, providers were supportive of the new vaccination requirements and reported that their facilities were equipped to accommodate the increased demand for vaccination visits prior to the beginning of the school year. There were modest increases in Tdap and MCV4 vaccination rates among 12-13-year-old adolescents by mid-September and a significant increase for MCV4 among 17-18-year-old adolescents (p > .001) in all regions. There were also statistically significant increases (p > .001) in MenB and HPV vaccination rates in this older age group. Our results suggest that these amended school-entry vaccination requirements may help improve timely vaccination rates for both required and non-required vaccines, increasing protection among students at the beginning of the school year.

Under-immunization of pediatric transplant recipients: a call to action for the pediatric community

Vaccine-preventable infections (VPIs) are a common and serious complication following transplantation. One in six pediatric solid organ transplant recipients is hospitalized with a VPI in the first 5 years following transplant and these hospitalizations result in significant morbidity, mortality, graft injury, and cost. Immunizations are a minimally invasive, cost-effective approach to reducing the incidence of VPIs. Despite published recommendations for transplant candidates to receive all age-appropriate immunizations, under-immunization remains a significant problem, with the majority of transplant recipients not up-to-date on age-appropriate immunizations at the time of transplant. This is extremely concerning as the rate for non-medical vaccine exemptions in the United States (US) is increasing, decreasing the reliability of herd immunity to protect patients undergoing transplant from VPIs. There is an urgent need to better understand barriers to vaccinating this population of high-risk children and to develop effective interventions to overcome these barriers and improve immunization rates. Strengthened national policies requiring complete age-appropriate immunization for non-emergent transplant candidates, along with improved multi-disciplinary immunization practices and tools to facilitate and ensure complete immunization delivery to this high-risk population, are needed to ensure that we do everything possible to prevent infectious complications in pediatric transplant recipients.

Religious Vaccine Exemptions in Kindergartners: 2011-2018

BACKGROUND

Forty-five states permit religious exemptions to school immunization laws; 15 allow personal belief exemptions. Updated religious exemption estimates are lacking, and it is unclear if personal belief exemption availability impacts religious exemption rates. We aimed to (1) update religious exemption trends in kindergartners, (2) compare states' proportions of kindergartners with religious exemptions by personal belief exemption availability, and (3) describe whether the proportion of kindergartners with religious exemptions changed in Vermont after it eliminated personal belief exemptions in 2016.

METHODS

We analyzed Centers for Disease Control and Prevention data on exemptions for children entering kindergarten from 2011 to 2018, including 295 state-years in our final analysis. Using a quasi-binomial regression analysis, we compared mean proportions of kindergartners with religious exemptions in states allowing both nonmedical exemptions against states with religious exemptions only, adjusting for policy strength and school year.

RESULTS

States with religious and personal belief exemptions were one-fourth as likely to have kindergartners with religious exemptions as states with religious exemptions only (risk ratio 0.25; 95% confidence interval 0.16-0.38). After Vermont's policy change, the mean proportion of kindergartners with a religious exemption increased from 0.5% to 3.7%. States were significantly more likely to have kindergartners with religious exemptions during the 2017-2018 school year compared with the 2011-2012 school year (P = .04).

CONCLUSIONS

Religious exemption rates appear to be associated with personal belief exemption availability, may be subject to a replacement effect on personal belief exemption elimination, and are increasing. Researchers and policy makers should confirm findings with individual-level studies and reconsider the purpose and nature of religious exemption laws.

The 2016 California policy to eliminate nonmedical vaccine exemptions and changes in vaccine coverage: An empirical policy analysis

BACKGROUND

Vaccine hesitancy, the reluctance or refusal to receive vaccination, is a growing public health problem in the United States and globally. State policies that eliminate nonmedical ("personal belief") exemptions to childhood vaccination requirements are controversial, and their effectiveness to improve vaccination coverage remains unclear given limited rigorous policy analysis. In 2016, a California policy (Senate Bill 277) eliminated nonmedical exemptions from school entry requirements. The objective of this study was to estimate the association between California's 2016 policy and changes in vaccine coverage.

METHODS AND FINDINGS

We used a quasi-experimental state-level synthetic control analysis and a county-level difference-in-differences analysis to estimate the impact of the 2016 California policy on vaccination coverage and prevalence of exemptions to vaccine requirements (nonmedical and medical). We used publicly available state-level data from the US Centers for Disease Control and Prevention on coverage of measles, mumps, and rubella (MMR) vaccination, nonmedical exemption, and medical exemption in children entering kindergarten. We used county-level data individually requested from state departments of public health on overall vaccine coverage and exemptions. Based on data availability, we included state-level data for 45 states, including California, from 2011 to 2017 and county-level data for 17 states from 2010 to 2017. The prespecified primary study outcome was MMR vaccination in the state analysis and overall vaccine coverage in the county analysis. In the state-level synthetic control analysis, MMR coverage in California increased by 3.3% relative to its synthetic control in the postpolicy period (top 2 of 43 states evaluated in the placebo tests, top 5%), nonmedical exemptions decreased by 2.4% (top 2 of 43 states evaluated in the placebo tests, top 5%), and medical exemptions increased by 0.4% (top 1 of 44 states evaluated in the placebo tests, top 2%). In the county-level analysis, overall vaccination coverage increased by 4.3% (95% confidence interval [CI] 2.9%-5.8%, p < 0.001), nonmedical exemptions decreased by 3.9% (95% CI 2.4%-5.4%, p < 0.001), and medical exemptions increased by 2.4% (95% CI 2.0%-2.9%, p < 0.001). Changes in vaccination coverage across counties after the policy implementation from 2015 to 2017 ranged from -6% to 26%, with larger increases in coverage in counties with lower prepolicy vaccine coverage. Results were robust to alternative model specifications. The limitations of the study were the exclusion of a subset of US states from the analysis and the use of only 2 years of postpolicy data based on data availability.

CONCLUSIONS

In this study, implementation of the California policy that eliminated nonmedical childhood vaccine exemptions was associated with an estimated increase in vaccination coverage and a reduction in nonmedical exemptions at state and county levels. The observed increase in medical exemptions was offset by the larger reduction in nonmedical exemptions. The largest increases in vaccine coverage were observed in the most "high-risk" counties, meaning those with the lowest prepolicy vaccine coverage. Our findings suggest that government policies removing nonmedical exemptions can be effective at increasing vaccination coverage.

Safety and Varicella Outcomes in In Utero-Exposed Newborns and Preterm Infants Treated With Varicella Zoster Immune Globulin (VARIZIG): A Subgroup Analysis of an Expanded-Access Program

BACKGROUND

Infants exposed to varicella zoster virus (VZV) in utero ≤5 days before or ≤48 hours after delivery and preterm infants are at high risk for varicella complications. An expanded-access program assessed varicella outcomes after administration of varicella zoster immune globulin (human) (VARIZIG) in a real-world setting.

METHODS

In this open-label, expanded-access program, high-risk infants received ≤125 IU/10 kg of VARIZIG (NCT00338442). VZV outcomes and safety were assessed.

RESULTS

There were 43 newborns exposed to VZV in utero and 80 preterm infants exposed to VZV; >80% received VARIZIG within 96 hours of reported exposure. When varicella outcomes were available, varicella occurred in 7 of 38 (18%) in utero-exposed newborns and zero of 65 preterm infants. Varicella-related complications were reported in 3 in utero-exposed newborns (3 with >100 lesions, 1 each with encephalitis and pneumonia). Adverse events were reported for 16% of in utero-exposed newborns and 25% of preterm infants, but few were considered related to VARIZIG. There were no deaths attributable to varicella or VARIZIG.

CONCLUSIONS

Varicella incidence and morbidity were low in in utero-exposed infants and zero in preterm infants who received prophylactic VARIZIG. There were few VARIZIG-related safety concerns.

Legislative and administrative actions to increase vaccination coverage in Washington schools

Current outbreaks of vaccine-preventable diseases in the U.S. highlight the consequences of declining levels of vaccination coverage. Attempts to increase coverage by banning or restricting nonmedical exemptions from school-entry vaccination requirements disregard children not up to date on vaccination who already attend school and those who are not up to date for reasons other than vaccine hesitancy. We analyze the potential effects of legislative and administrative options to increase vaccination coverage in Washington schools. We constructed a grade-specific model of the detailed vaccination status for all required vaccines and the MMR vaccine specifically for all children in the state's school system. We used scenario modeling to evaluate the effects of potential legislative and administrative actions on the percent of students up to date on all required vaccines and the MMR vaccine from 2018 to 2030. Our analysis shows that eliminating nonmedical exemptions may not be the optimal solution for reducing disease outbreak risk. Instead, focusing on children not up to date for reasons other than nonmedical exemption could have a larger impact and does not carry the controversy that accompanies attempts to ban or restrict nonmedical exemptions. Further, implementing a one-time catch-up period for all children not up to date would increase coverage promptly. Evidence-based policymaking is an essential component of efforts to reduce the risk of disease outbreaks in U.S. schools, and analysis of potential legislative and administrative actions complement these efforts.

Measles outbreaks and public attitudes towards vaccine exemptions: some cautions and strategies for addressing vaccine hesitancy

Today, the United States and countries throughout the world are experiencing measles outbreaks that have sickened thousands of children. From the Disneyland outbreak in 2014 to today, some states have responded with changes in laws on vaccine requirements and exemptions. In this article, we examine the history of vaccine laws, and using our 2015 survey data, explore to what extent the news coverage of the Disneyland outbreak altered parents' attitudes toward required vaccination and non-medical exemptions. We explore those results in the context of today's increasing polarized and politicalized battle over vaccine laws, and consider how health care providers and policy makers can work to improve public attitudes about vaccines.

Vaccination Coverage with Selected Vaccines and Exemption Rates Among Children in Kindergarten - United States, 2018-19 School Year

State and local school vaccination requirements exist to ensure that students are protected against vaccine-preventable diseases (1). This report summarizes data collected by state and local immunization programs* on vaccination coverage among children in kindergarten in 49 states, exemptions for kindergartners in 50 states, and provisional enrollment and grace period status for kindergartners in 30 states. Nationally, vaccination coverage^† was 94.9% for the state-required number of doses of diphtheria and tetanus toxoids, and acellular pertussis vaccine (DTaP); 94.7% for 2 doses of measles, mumps, and rubella vaccine (MMR); and 94.8% for the state-required doses of varicella vaccine. Whereas 2.5% of kindergartners had an exemption from at least one vaccine,^§ 2.8% of kindergartners were not up to date for MMR and did not have a vaccine exemption. Nearly all states could achieve the recommended ≥95% MMR coverage if all nonexempt kindergartners were vaccinated in accordance with local and state vaccination policies.

Denver Religious Leaders' Vaccine Attitudes, Practices, and Congregational Experiences

Religious vaccine exemptions are widely available in America and increased in the past decade for unclear reasons. Religious leaders strive to influence their congregants' attitudes and practices. We sought to describe Denver religious leaders' vaccine attitudes, practices, and congregational experiences using a cross-sectional online survey. The response rate was 33% (109/334). Most respondents were Protestant, White, male, parents; 42% believed the Bible contained themes supportive of vaccination, 25% were vaccine hesitant, and only 10% had addressed vaccines in their congregations. Vaccine-hesitant religious leaders' attitudes and practices differed from those of non-hesitant leaders. Study implications and future research avenues are discussed.

Myths and Misconceptions: Varicella-Zoster Virus Exposure, Infection Risks, Complications, and Treatments

Varicella zoster and herpes zoster are infections caused by the highly contagious varicella-zoster virus (VZV). Despite widespread availability of vaccines against VZV, as well as varicella vaccination rates >95%, VZV remains a public health concern because of several common myths and misconceptions. Because of the success of routine varicella vaccination programs, some people mistakenly believe that varicella and herpes zoster are now no longer a threat to public health. Another common misconception is that shingles is less infectious than varicella; however, clinical evidence indicates otherwise. Several knowledge gaps exist around VZV transmission and the availability and use of varicella zoster immune globulin (human) for postexposure prophylaxis against VZV. To help reduce the incidence of severe disease in high-risk individuals (eg, elderly people, pregnant women, unvaccinated persons, infants, and immunocompromised children and adults), this article addresses misbeliefs and broadens awareness of VZV exposure, infection risks, complications, and treatments.

The MMR Vaccine and Autism

Autism is a developmental disability that can cause significant social, communication, and behavioral challenges. A report published in 1998, but subsequently retracted by the journal, suggested that measles, mumps, and rubella (MMR) vaccine causes autism. However, autism is a neurodevelopmental condition that has a strong genetic component with genesis before one year of age, when MMR vaccine is typically administered. Several epidemiologic studies have not found an association between MMR vaccination and autism, including a study that found that MMR vaccine was not associated with an increased risk of autism even among high-risk children whose older siblings had autism. Despite strong evidence of its safety, some parents are still hesitant to accept MMR vaccination of their children. Decreasing acceptance of MMR vaccination has led to outbreaks or resurgence of measles. Health-care providers have a vital role in maintaining confidence in vaccination and preventing suffering, disability, and death from measles and other vaccine-preventable diseases.

Community members trusted by African American parents for vaccine advice

Exposure to pro-vaccination messages from nonmedical peers and others perceived to share a similar value system for society (referred to as worldview outlook) improves vaccination attitudes. Nonetheless, a minority of African American parents have friends and family members who provide them with vaccine advice. The aims of the current study were to identify the presumed worldview outlook of eight types of community figures as perceived by African American parents, and determine parents' trust in these figures for vaccine advice, and whether trust varied according to the figures' racial concordance. A cross-sectional survey was administered to 110 African American parents in 2015. Parents perceived the community figures to represent a spectrum of worldview outlooks. Although levels of trust in the community figures differed overall (p < .001), it was high in the school nurse, pediatrician, mother, father, disease survivor, and vaccine scientist. All trusted figures except the father were perceived to hold a communitarian outlook. Parents shown race-concordant figures had higher levels of trust in them than those who were shown race-discordant equivalents (p < .01). These findings suggest that vaccination campaigns geared toward African American parents may be strengthened by including other nonmedical, African American spokespersons who convey their community contributions in messages.

Current landscape of nonmedical vaccination exemptions in the United States: impact of policy changes

INTRODUCTION

In the United States, high childhood vaccination coverage has reduced the morbidity and mortality due to vaccine-preventable diseases. The success of vaccination programs in achieving this high coverage is due, in part, to vaccination mandates for school entry. All states have such mandates, but there is heterogeneity across the states in the allowance of non-medical exemptions (e.g. religious or personal belief exemptions) to these mandates.

AREAS COVERED

We examine historical trends in non-medical exemption prevalence in the US, discuss recent state-level policy changes that may impact non-medical exemption prevalence, and review recent studies on the association between non-medical exemptions and infectious disease outbreaks.

EXPERT COMMENTARY

State-level implementation of mandates, and related allowances for medical and non-medical exemptions, varies greatly across the United States. Non-medical exemption rates have increased over the last two decades, with an increased risk of disease outbreaks in clusters of children with non-medical exemptions due to differences in state laws. Recent efforts to address non-medical exemption rates range from incorporating additional administrative requirements for exemptions and disallowance of any non-medical exemptions. Continued monitoring is needed to evaluate the impact of these changes on exemption rates, to develop optimal childhood vaccination policy across the United States.