MMR vaccination status of children exempted from school-entry immunization mandates

Provisional Entrants, Exemptions, and Kindergarteners Up-to-Date on Vaccination Before and After a Regulatory Change in Pennsylvania, 2015-2019

OBJECTIVES

Before the 2017-2018 school year, Pennsylvania shortened the grace period for provisional entrants-kindergarteners who are not up-to-date on vaccination and do not have medical or nonmedical exemption-from 8 months to 5 days. We analyzed the impact of this change on school-entry vaccination status.

METHODS

Using data from the Pennsylvania Department of Health for school years 2015-2016 through 2018-2019, we examined state-level trends in Pennsylvania kindergarteners' vaccination status, including the percentage who were up-to-date on each required vaccine, provisionally enrolled, medically exempted from vaccination, and nonmedically exempted from vaccination. Using the Spearman correlation coefficient, we assessed associations at the school level among changes in kindergarteners' vaccination status after the grace period was shortened.

RESULTS

From 2016-2017 to 2017-2018, the provisional entrance rate of kindergarteners in Pennsylvania decreased substantially after the change in the grace period (from 8.1% to 2.2%), the medical exemption rate remained stable, and the nonmedical exemption rate increased slightly (from 1.8% to 2.5%). The percentage of kindergarteners up-to-date on required vaccines increased or remained stable across the study period except for polio, which decreased from 97.9% in 2015-2016 to 96.2% in 2018-2019. The change in provisional entrance rate was negatively associated with change in kindergarteners up-to-date on required vaccines (ρ range, -0.30 to -0.70) but not with change in medical or nonmedical exemptions (ρ range, -0.01 to -0.08).

CONCLUSIONS

Efforts to reduce provisional entrants may increase the percentage of kindergarteners up-to-date on vaccinations at school entry without a corresponding increase in exemptions.

Spatial Clustering of Vaccine Exemptions on the Risk of a Measles Outbreak

OBJECTIVES

Areas of increased school-entry vaccination exemptions play a key role in epidemics of vaccine-preventable diseases in the United States. California eliminated nonmedical exemptions in 2016, which increased overall vaccine coverage but also rates of medical exemptions. We examine how spatial clustering of exemptions contributed to measles outbreak potential pre- and postpolicy change.

METHODS

We modeled measles transmission in an empirically calibrated hypothetical population of youth aged 0 to 17 years in California and compared outbreak sizes under the observed spatial clustering of exemptions in schools pre- and postpolicy change with counterfactual scenarios of no postpolicy change increase in medical exemptions, no clustering of exemptions, and lower population immunization levels.

RESULTS

The elimination of nonmedical exemptions significantly reduced both average and maximal outbreak sizes, although increases in medical exemptions resulted in more than twice as many infections, on average, than if medical exemptions were maintained at prepolicy change levels. Spatial clustering of nonmedical exemptions provided some initial protection against random introduction of measles infections; however, it ultimately allowed outbreaks with thousands more infections than when exemptions were randomly distributed. The large-scale outbreaks produced by exemption clusters could not be reproduced when exemptions were distributed randomly until population vaccination was lowered by >6 percentage points.

CONCLUSIONS

Despite the high overall vaccinate rate, the spatial clustering of exemptions in schools was sufficient to threaten local herd immunity and reduce protection from measles outbreaks. Policies strengthening vaccine requirements may be less effective if alternative forms of exemptions (eg, medical) are concentrated in existing low-immunization areas.

Perspectives on state vaccine education mandate policy and implementation among public health department officials: a qualitative study

In response to the increase in non-medical vaccine exemptions (NME), many states have adopted education mandates (EM), required vaccine education for parents requesting NMEs for their school-age children, but these EMs vary greatly in implementation. In order to learn about the administrative aspects of each state's EM, we interviewed fourteen health department officials from nine states with EMs. Interviews were conducted over the phone, transcribed by a professional transcription service, and double-coded using NVivo 12 by two members of the study staff. The coding resulted in 3698 comments overall, 98.5% inter-coder reliability, and a κ statistic of 0.691. We found no consistent format for content delivery, and methods used included in-person dialogs, web-based education, and video modules. Content of the education is not standardized, and education length ranges from 15 to 60 minutes. Four major themes about the EM policies emerged: (1) the use of EMs to eliminate "convenience exemptions;" (2) the importance of health department communication with health-care providers; (3) facilitators and barriers to implementation; and (4) the positive recommendation for other states to adopt EM policies. We concluded that current EM implementation varies greatly, but officials in states which have adopted EMs for parents requesting NMEs for school-entry vaccinations overwhelmingly recommend other states to adopt them as well. Key features of successful programs may include conversations with parents requesting NMEs and strong communication channels with health-care providers. Systematic tracking of vaccine status after exemption requests and education is necessary to quantitatively determine the effectiveness of EM programs.

Conscientious vaccination exemptions in kindergarten to eighth-grade children across Texas schools from 2012 to 2018: A regression analysis

BACKGROUND

As conscientious vaccination exemption (CVE) percentages rise across the United States, so does the risk and occurrence of outbreaks of vaccine-preventable diseases such as measles. In the state of Texas, the median CVE percentage across school systems more than doubled between 2012 and 2018. During this period, the proportion of schools surpassing a CVE percentage of 3% rose from 2% to 6% for public schools, 20% to 26% for private schools, and 17% to 22% for charter schools. The aim of this study was to investigate this phenomenon at a fine scale.

METHODS AND FINDINGS

Here, we use beta regression models to study the socioeconomic and geographic drivers of CVE trends in Texas. Using annual counts of CVEs at the school system level from the 2012-2013 to the 2017-2018 school year, we identified county-level predictors of median CVE percentage among public, private, and charter schools, the proportion of schools below a high-risk threshold for vaccination coverage, and five-year trends in CVEs. Since the 2012-2013 school year, CVE percentages have increased in 41 out of 46 counties in the top 10 metropolitan areas of Texas. We find that 77.6% of the variation in CVE percentages across metropolitan counties is explained by median income, the proportion of the population that holds a bachelor's degree, the proportion of the population that self-reports as ethnically white, the proportion of the population that is English speaking, and the proportion of the population that is under the age of five years old. Across the 10 top metropolitan areas in Texas, counties vary considerably in the proportion of school systems reporting CVE percentages above 3%. Sixty-six percent of that variation is explained by the proportion of the population that holds a bachelor's degree and the proportion of the population affiliated with a religious congregation. Three of the largest metropolitan areas-Austin, Dallas-Fort Worth, and Houston-are potential vaccination exemption "hotspots," with over 13% of local school systems above this risk threshold. The major limitations of this study are inconsistent school-system-level CVE reporting during the study period and a lack of geographic and socioeconomic data for individual private schools.

CONCLUSIONS

In this study, we have identified high-risk communities that are typically obscured in county-level risk assessments and found that public schools, like private schools, are exhibiting predictable increases in vaccination exemption percentages. As public health agencies confront the reemerging threat of measles and other vaccine-preventable diseases, findings such as ours can guide targeted interventions and surveillance within schools, cities, counties, and sociodemographic subgroups.

Mandatory vaccination for infants and children: the Italian experience

Maintaining high vaccination coverage is important in order to protect the individual and the community. Mandatory vaccination is an option in case of declining coverage. Widely used in the USA, it is considered a rather controversial issue in Europe. In Italy, after a decrease of vaccination coverage for the hexavalent and the MPR vaccine under the optimal threshold, a new law, which extended the number of mandatory vaccines from 4 to 10 and reinforced coercive measures, was introduced in July 2017. After 2 years, vaccination coverage increased for all mandatory vaccines and for the other two recommended vaccines (anti-pneumococcal and anti-meningococcal C). Although it is not possible to disentangle the role of other factors contributing to the positive outcome, consistently with the results of studies conducted in the USA, vaccine mandates appeared to be successful in increasing vaccination coverage in Italy. The long-term sustainability of the effect of mandatory vaccination and the potential negative drawbacks of the coercive measures need to be evaluated to generate scientific evidence in public health.

Accelerating measles and rubella elimination through research and innovation - Findings from the Measles & Rubella Initiative research prioritization process, 2016

The Measles & Rubella Initiative (M&RI) identified five key strategies to achieve measles and rubella elimination, including research and innovation to support cost-effective operations and improve vaccination and diagnostic tools. In 2016, the M&RI Research and Innovation Working Group (R&IWG) completed a research prioritization process to identify key research questions and update the global research agenda. The R&IWG reviewed meeting reports and strategic planning documents and solicited programmatic inputs from vaccination experts at the program operational level through a web survey, to identify previous research priorities and new research questions. The R&IWG then convened a meeting of experts to prioritize the identified research questions in four strategic areas: (1) epidemiology and economics, (2) surveillance and laboratory, (3) immunization strategies, and (4) demand creation and communications. The experts identified 19 priority research questions in the four strategic areas to address key areas of work necessary to further progress toward elimination. Future commitments from partners will be needed to develop a platform for improved coordination with adequate and predictable resources for research implementation and innovation to address these identified priorities.

Mandatory Health Care Provider Counseling For Parents Led To A Decline In Vaccine Exemptions In California

Receipt of childhood vaccinations in the US has been declining, and outbreaks of preventable infectious diseases have become more common. In response, in 2014 California implemented a policy change for exemptions from mandatory vaccines for school enrollment. Data on fifteen successive cohorts of kindergarteners enrolled in public and private schools between school years 2001-02 and 2015-16 were analyzed for changes in vaccination trends. The results show an increase in the prevalence and clustering of vaccine exemptions from 2001-02 through 2013-14, followed by a modest decline after implementation of a policy mandating health care provider counseling for vaccine exemption. Clustering of vaccine exemptions increased over the study period and was less responsive to the policy change than were exemption rates overall. Nor did the policy change uniformly reduce the clustering of at-risk students across counties. Trends in the use of conditional admission showed strong school-level clustering and remained relatively stable. The policy change was effective at reducing exemption rates but did not uniformly reduce clustering of exemptions. The results suggest the need to evaluate the causes of local-area clustering and to adopt a statewide policy that addresses clustering of vaccine exemptions within schools and counties.

Training Students to Address Vaccine Hesitancy and/or Refusal

Objective. To determine the impact of a vaccine hesitancy learning unit on student knowledge, attitudes, and ability to address vaccine hesitancy and/or refusal. Methods. The learning unit consisted of two standardized patient simulation encounters performed one week apart. A 13-item attitudes survey was administered prior to the simulations to determine student confidence and knowledge regarding vaccine hesitancy. Students then participated in an encounter with a simulated patient who assessed the students' abilities using a 16-item grading rubric related to the art of the rhetoric, communication skills, and social, emotional competence. Post-simulation, students received feedback, completed a self-reflection exercise, and received formal coursework on addressing vaccine hesitancy. The following week, students participated in a second simulated patient encounter and thereafter completed the same attitudes and satisfaction surveys. Results. There were 203 students who went through the learning unit, with 180 (88.6% response rate) completing all the survey tools. The results showed significant improvements in all 16 items of the assessment rubric. On the pre/post attitudes questions, 9 out of 13 items showed significant improvement. Gains were largest for knowledge on the use of thimerosal as a preservative, speaking about how vaccines will not overwhelm a child's immune system, and knowledge about vaccinations not overwhelming a child's immune system. Overall, 94% of students were satisfied with the learning unit. Conclusion. This learning unit was effective in improving student confidence and ability to address vaccine hesitancy.

Parental attitudes and perceptions associated with childhood vaccine exemptions in high-exemption schools

Previous work demonstrates that individuals who obtain exemptions from school immunization requirements are geographically clustered, making regional differences in vaccination coverage a significant concern. Even where exemption levels are high, there are still parents that vaccinate. School-level assessments have determined that exemptors are more likely to attend wealthier schools with fewer minorities. Few studies have assessed divergent opinions within the context of a higher-exemption community to examine subtle differences in opinion surrounding vaccinations. Therefore, the objective of this work was to assess attitudes and perceptions towards vaccinations and compare them for exemptors and non-exemptors. We administered surveys to parents in high-exemption (>10%) elementary schools in Arizona during the 2012–13 school year. A total of 404 surveys were completed by parents among schools in Maricopa (n = 7) and Yavapai (n = 2) counties. Of these, 35% (n = 141) were exemptors and 65% (n = 261) were non-exemptors. Exemptors were more likely than non-exemptors to be concerned about serious side-effects (p<0.001). They were more likely to report knowing someone who had been diagnosed with a vaccine-preventable disease (p<0.001) but less likely to report that this had been a serious illness in that person (p<0.001) and they believed it is better for a child to develop immunity through illness than vaccination (p<0.001). They were less likely to trust physicians (p<0.001) and information about vaccines (p<0.001) and were more likely to obtain their health care from a naturopath (p<0.001). In summary, exemptors in these Arizona schools do not appear to be exempting their children from vaccinations due to convenience, as has been hypothesized in other settings. Based on the divergent views within high-exemption schools and reported distrust of the medical establishment, target interventions for high-exemption schools are discussed. Additionally, given the lack of effective non-policy based interventions to-date, the negligible declines in personal belief exemption rates, and vaccine preventable disease rate increases in Arizona, especially in high-exemption areas, legislative action in Arizona may also warrant further investigation.

Conditional admission, religious exemption type, and nonmedical vaccine exemptions in California before and after a state policy change

Recent measles and pertussis outbreaks in the US have focused national attention on state laws governing exemptions from mandatory vaccines for school entry. After several years of increases in nonmedical exemptions in California, the state assembly passed Assembly Bill 2109 in 2012, making nonmedical exemptions more difficult to obtain by requiring parents to obtain a signature from a health care provider. We used data from the California Department of Public Health to describe changes in the overall prevalence of personal belief exemptions and compositional changes in immunization status for the school years 2012-2013 through 2015-2016. Following the implementation of Assembly Bill 2109, the statewide exemption rate declined from 3.1% in 2013 to 2.5% in 2014 and then to 2.3% in 2015, representing a 25% reduction from the 2013 peak. Continued surveillance of exemption rates and vaccine refusal are needed to monitor and protect herd immunity against vaccine-preventable diseases.

Examining the spatiotemporal evolution of vaccine refusal: nonmedical exemptions from vaccination in California, 2000-2013

BACKGROUND

Vaccine hesitancy continues to be an issue throughout the United States, as numerous vaccine hesitant parents are choosing to exempt their children from school-entry vaccination requirements for nonmedical reasons, despite the safety and effectiveness of vaccines. We conduct an analysis of how vaccine refusal, measured by the use of nonmedical exemptions (based on personal or religious beliefs) from vaccination (NMEs), evolved across space and over time in California.

METHODS

Using school-entry data from the California Department of Public Health, we examined NMEs for students entering kindergarten in California from 2000 to 2013. We conduct global and local spatial autocorrelation analysis to determine whether NME use became more geographically clustered over the study period and whether the location of local clusters of high use were temporally stable. We conducted a grouping analysis that identified the general temporal trends in NME use over the time period.

RESULTS

The use of NMEs increased from 0.73% of all kindergarteners in 2000 to 3.09% in 2013 and became more geographically clustered over the study period. Local geographic clusters of high use were relatively isolated early in the study period, but expanded in size over time. The grouping analysis showed that regions with high NME use early in the study period were generally few (15% of all US Census tracts) and relatively isolated. Regions that had low initial NME use and moderate to large increases over the study period were located in close proximity to the initial high use regions. The grouping analysis also showed that roughly half of all tracts had 0% or very low NME use throughout the study period.

CONCLUSIONS

We found an observable spatial structure to vaccine refusal and NME use over time, which appeared to be a self-reinforcing process, as well as a spatially diffusive process. Importantly, we found evidence that use of NMEs in the initially isolated regions appeared to stimulate vaccine refusal in geographically proximal regions. Thus, our results suggest that efforts aimed at decreasing future NME use may be most effective if they target regions where NME use is already high, as well as the nearby regions.

Do changes in socio-demographic characteristics impact up-to-date immunization status between 3 and 24 months of age? A prospective study among an inner-city birth cohort in the United States

INTRODUCTION

Low-income child populations remain under-vaccinated. Our objective was to determine differences in the relative importance of maternal health literacy and socio-demographic characteristics that often change during early childhood on up-to-date (UTD) immunization status among a low-income population.

METHODS

We performed secondary data analysis of a longitudinal prospective cohort study of 744 Medicaid-eligible mother-infant dyads recruited at the time of the infant's birth from an inner-city hospital in the United States and surveyed every 6 months for 24 months. Our primary outcome was infant UTD status at 24 months abstracted from a citywide registry. We assessed maternal health literacy with the Test of Functional Health Literacy in Adults (short version). We collected socio-demographic information via surveys at birth and every 6 months. We compared predictors of UTD status at 3, 7, and 24 months.

RESULTS

The cohort consisted of primarily African-American (81.5%) mothers with adequate health literacy (73.9%). Immunizations were UTD among 56.7% of infants at 24 months of age. Maternal health literacy was not a significant predictor of UTD immunization status. Instead, adjusted results showed that significant predictors of not-UTD status at 24 months were lack of a consistent health care location or "medical home" (OR 0.17, 95%CI 0.18-0.37), inadequate prenatal care (OR 0.48, 95%CI 0.25-0.95), and prior not-UTD status (OR 0.31, 95%CI 0.20-0.47). Notably, all upper confidence limits are less than 1.0 for these variables. Health care location type (e.g., hospital-affiliate, community-based, none) was a significant predictor of vaccine status at age 3 months, 7 months, and 24 months.

CONCLUSIONS

Investing in efforts to support early establishment of a medical home to obtain comprehensive coordinated preventive care, including providing recommended vaccines on schedule, is a prudent strategy to improve vaccination status at the population level.

Estimating enhanced prevaccination measles transmission hotspots in the context of cross-scale dynamics

A key question in clarifying human-environment interactions is how dynamic complexity develops across integrative scales from molecular to population and global levels. Apart from its public health importance, measles is an excellent test bed for such an analysis. Simple mechanistic models have successfully illuminated measles dynamics at the city and country levels, revealing seasonal forcing of transmission as a major driver of long-term epidemic behavior. Seasonal forcing ties closely to patterns of school aggregation at the individual and community levels, but there are few explicit estimates of school transmission due to the relative lack of epidemic data at this scale. Here, we use data from a 1904 measles outbreak in schools in Woolwich, London, coupled with a stochastic Susceptible-Infected-Recovered model to analyze measles incidence data. Our results indicate that transmission within schools and age classes is higher than previous population-level serological data would suggest. This analysis sheds quantitative light on the role of school-aged children in measles cross-scale dynamics, as we illustrate with references to the contemporary vaccination landscape.

Childhood Vaccination: Implications for Global and Domestic Public Health

The role of vaccination in the control and prevention of endemic and emerging diseases cannot be overemphasized. Induction of host protective immunity may be the most powerful tool and effective strategy in preventing the spread of potentially fatal disease and emerging illnesses, in particular in susceptible immunologically naive hosts. The strategy for vaccination programs is engrained in population studies recognizing benefit for the health and economic welfare of at-risk indigenous populations. Worldwide collaboration is a necessary aspect of vaccine-preventable diseases recognizing that even a small number of wild-type cases of an eradicated disease in one region presents opportunities for re-emergence of the disease in geographically remote areas.