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

PEDIATRICS ◽  
2021 ◽  
Vol 149 (1) ◽  
Author(s):  
Ashley Gromis ◽  
Ka-Yuet Liu
Keyword(s):  
Large Scale ◽  
Spatial Clustering ◽  
Vaccine Coverage ◽  
Herd Immunity ◽  
The United States ◽  
Vaccine Preventable Diseases ◽  
Measles Outbreak ◽  
Measles Outbreaks ◽  
Lower Population ◽  
Local Herd

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.

scholarly journals Getting personal: how vaccination exemptions shape herd immunity

2018 ◽  
Author(s):  
Emma R Nedell ◽  
Romain Garnier ◽  
Saad B Omer ◽  
Shweta Bansal
Keyword(s):  
Policy Change ◽  
Spatial Clustering ◽  
Vaccine Coverage ◽  
Herd Immunity ◽  
The United States ◽  
Vaccine Preventable Diseases ◽  
Vaccination Rates ◽  
Before And After ◽  
Exemption Policy ◽  
Epidemiological Effects

Background: State-mandated school entry immunization requirements in the United States play an important role in achieving high vaccine coverage and preventing outbreaks of vaccine-preventable diseases. Most states allow non-medical exemptions that let children remain unvaccinated on the basis of personal beliefs. However, the ease of obtaining such exemptions varies, resulting in a patchwork of state vaccination exemption laws, contributing to heterogeneity in vaccine coverage across the country. In this study, we evaluate epidemiological effects and spatial variations in non-medical exemption rates in the context of vaccine policies. Methods and Findings: We first analyzed the correlation between non-medical exemption rates and vaccine coverage for three significant childhood vaccinations and found that higher rates of non-medical exemptions were associated with lower vaccination rates of school-aged children in all cases. We then identified a subset of states where exemption policy has recently changed and found that the effects on statewide non-medical exemption rates varied widely. Focusing further on Vermont and California, we illustrated how the decrease in non-medical exemptions due to policy change was concurrent to an increase in medical exemptions (in CA) or religious exemptions (in VT). Finally, a spatial clustering analysis was performed for Connecticut, Illinois, and California, identifying clusters of high non-medical exemption rates in these states before and after a policy change occurred. The clustering analyses show that policy changes affect spatial distribution of non-medical exemptions within a state. 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.

scholarly journals An agent-based model of school closing in under-vaccinated communities during measles outbreaks

SIMULATION ◽  
2017 ◽  
Vol 95 (5) ◽  
pp. 385-393 ◽  
Author(s):  
Wayne M Getz ◽  
Colin Carlson ◽  
Eric Dougherty ◽  
Travis C Porco ◽  
Richard Salter
Keyword(s):  
Vaccination Coverage ◽  
Herd Immunity ◽  
The United States ◽  
Vaccination Rate ◽  
Agent Based ◽  
School Closing ◽  
Measles Outbreak ◽  
Measles Outbreaks ◽  
Low Coverage ◽  
Range Of Values

The winter 2014–15 measles outbreak in the United States represents a significant crisis in the emergence of a functionally extirpated pathogen. Conclusively linking this outbreak to decreases in the measles, mumps, and rubella (MMR) vaccination rate (driven by anti-vaccine sentiment) is critical to motivating MMR vaccination. We used the NOVA modeling platform to build a stochastic, spatially-structured, individual-based SEIR model of outbreaks, under the assumption that [Formula: see text] for measles. We show this implies that herd immunity requires vaccination coverage of greater than approximately 85%. We used a network structured version of our NOVA model that involved two communities, one at the relatively low coverage of 85% coverage and one at the higher coverage of 95%, both of which had 400-student schools embedded, as well as students occasionally visiting superspreading sites (e.g., high-density theme parks, and cinemas). These two vaccination coverage levels are within the range of values occurring across Californian counties. Transmission rates at schools and superspreading sites were arbitrarily set to respectively 5 and 15 times the background community rates. Simulations of our model demonstrate that a ‘send unvaccinated students home’ policy in low coverage counties is extremely effective at shutting down outbreaks of measles.

scholarly journals Assessing the distribution and determinants of vaccine underutilization in the United States

2017 ◽  
Author(s):  
Sandra Goldlust ◽  
Elizabeth C. Lee ◽  
Murali Haran ◽  
Pejman Rohani ◽  
Shweta Bansal
Keyword(s):  
United States ◽  
Large Scale ◽  
Herd Immunity ◽  
The United States ◽  
Vaccine Uptake ◽  
Vaccine Hesitancy ◽  
Economic Determinants ◽  
Vaccine Preventable Diseases ◽  
Coverage Rates ◽  
Public Health Strategies

AbstractDespite advances in sanitation and immunization, vaccine-preventable diseases remain a significant cause of morbidity and mortality worldwide. In high-income countries such as the United States, coverage rates for vaccination against childhood infections remains high. However, the phenomenon of vaccine hesitancy makes maintenance of herd immunity difficult, impeding global disease eradication efforts. Reaching the ‘last mile’ will require early detection of vaccine hesitancy (driven by philosophical or religious choices), identifying pockets of susceptibility due to underimmunization (driven by vaccine unavailability, costs ineligibility), determining the factors associated with the behavior and developing targeted strategies to ameliorate the concerns. Towards this goal, we harness high-resolution medical claims data to geographically localize vaccine refusal and underimmunization (collectively, ‘underutilization’) in the United States and identify the socio-economic determinants of the behaviors. Our study represents the first large-scale effort for vaccination behavior surveillance and has the potential to aid in the development of targeted public health strategies for optimizing vaccine uptake.

scholarly journals Verification of Healthcare Personnel Immunity as a Strategy for Measles Preparedness

2020 ◽  
Vol 41 (S1) ◽  
pp. s431-s432
Author(s):  
Rachael Snyders ◽  
Hilary Babcock ◽  
Christopher Blank
Keyword(s):  
Infectious Diseases ◽  
Multidisciplinary Team ◽  
The United States ◽  
Transmission Risk ◽  
Healthcare Personnel ◽  
Serological Tests ◽  
Preparedness Plan ◽  
Vaccine Preventable Diseases ◽  
Measles Outbreaks ◽  
Centralized Database

Background: Immunization resistance is fueling a resurgence of vaccine-preventable diseases in the United States, where several large measles outbreaks and 1,282 measles cases were reported in 2019. Concern about these measles outbreaks prompted a large healthcare organization to develop a preparedness plan to limit healthcare-associated transmission. Verification of employee rubeola immunity and immunization when necessary was prioritized because of transmission risk to nonimmune employees and role of the healthcare personnel in responding to measles cases. Methods: The organization employs ∼31,000 people in diverse settings. A multidisciplinary team was formed by infection prevention, infectious diseases, occupational health, and nursing departments to develop the preparedness plan. Immunity was monitored using a centralized database. Employees without evidence of immunity were asked to provide proof of vaccination, defined by the CDC as 2 appropriately timed doses of rubeola-containing vaccine, or laboratory confirmation of immunity. Employees were given 30 days to provide documentation or to obtain a titer at the organization’s expense. Staff with negative titers were given 2 weeks to coordinate with the occupational heath department for vaccination. Requests for medical or religious accommodations were evaluated by occupational heath staff, the occupational heath medical director, and the human resources department. All employees were included, though patient-interfacing employees in departments considered higher risk were prioritized. These areas were the emergency, dermatology, infectious diseases, labor and delivery, obstetrics, and pediatrics departments. Results: At the onset of the initiative in June 2019, 4,009 employees lacked evidence of immunity. As of November 2019, evidence of immunity had been obtained for 3,709 employees (92.5%): serological evidence of immunity was obtained for 2,856 (71.2%), vaccine was administered to 584 (14.6%), and evidence of previous vaccination was provided by 269 (6.7%). Evidence of immunity has not been documented for 300 (7.5%). The organization administered 3,626 serological tests and provided 997 vaccines, costing ∼$132,000. Disposition by serological testing is summarized in Table 1. Conclusions: A measles preparedness strategy should include proactive assessment of employees’ immune status. It is possible to expediently assess a large number of employees using a multidisciplinary team with access to a centralized database. Consideration may be given to prioritization of high-risk departments and patient-interfacing roles to manage workload.Funding: NoneDisclosures: None

scholarly journals The importance of supplementary immunisation activities to prevent measles outbreaks during the COVID-19 pandemic in Kenya

BMC Medicine ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
C. N. Mburu ◽  
◽  
J. Ojal ◽  
R. Chebet ◽  
D. Akech ◽  
...  
Keyword(s):  
Vaccination Coverage ◽  
Herd Immunity ◽  
African Region ◽  
Population Immunity ◽  
Measles Outbreak ◽  
Increased Risk ◽  
Measles Vaccination ◽  
Serological Data ◽  
Measles Outbreaks ◽  
Measles Vaccination Coverage

Abstract Background The COVID-19 pandemic has disrupted routine measles immunisation and supplementary immunisation activities (SIAs) in most countries including Kenya. We assessed the risk of measles outbreaks during the pandemic in Kenya as a case study for the African Region. Methods Combining measles serological data, local contact patterns, and vaccination coverage into a cohort model, we predicted the age-adjusted population immunity in Kenya and estimated the probability of outbreaks when contact-reducing COVID-19 interventions are lifted. We considered various scenarios for reduced measles vaccination coverage from April 2020. Results In February 2020, when a scheduled SIA was postponed, population immunity was close to the herd immunity threshold and the probability of a large outbreak was 34% (8–54). As the COVID-19 contact restrictions are nearly fully eased, from December 2020, the probability of a large measles outbreak will increase to 38% (19–54), 46% (30–59), and 54% (43–64) assuming a 15%, 50%, and 100% reduction in measles vaccination coverage. By December 2021, this risk increases further to 43% (25–56), 54% (43–63), and 67% (59–72) for the same coverage scenarios respectively. However, the increased risk of a measles outbreak following the lifting of all restrictions can be overcome by conducting a SIA with ≥ 95% coverage in under-fives. Conclusion While contact restrictions sufficient for SAR-CoV-2 control temporarily reduce measles transmissibility and the risk of an outbreak from a measles immunity gap, this risk rises rapidly once these restrictions are lifted. Implementing delayed SIAs will be critical for prevention of measles outbreaks given the roll-back of contact restrictions in Kenya.

Pertussis

2018 ◽  
Keyword(s):  
Public Health ◽  
Disease Ecology ◽  
Evolutionary Biology ◽  
Expert Knowledge ◽  
Whooping Cough ◽  
Vaccine Coverage ◽  
The United States ◽  
Vaccine Preventable Diseases ◽  
Treatment And Prevention ◽  
Evolutionary Epidemiology

Pertussis, or whooping cough, is a respiratory disease caused primarily by infection with the bacterium Bordetella pertussis. It remains one of the leading causes of death among vaccine-preventable diseases worldwide and recent years have seen its alarming re-emergence in many regions (including the United States and much of Europe), despite sustained high levels of vaccine coverage. The causes of the resurgence remain contentious, in part due to inherent complexities of the pathogen’s biology, in part due to pronounced variation in the treatment and prevention strategies between different countries and regions, and in part due to long-standing disagreement among scientific researchers studying pertussis. This edited volume brings together expert knowledge from disparate fields with the overall aim of synthesizing the current understanding of this critically important, global pathogen. Pertussis: Epidemiology, Immunology, and Evolution is an advanced text suitable for graduate-level students taking courses in evolutionary epidemiology, disease ecology, and evolutionary biology, as well as academics, public health officials, and researchers in these fields. It also offers a very useful introduction to a wider audience of public health practitioners, microbiologists, epidemiologists, medical professionals, and vaccine biologists

scholarly journals A Review of Measles Outbreak Cost Estimates From the United States in the Postelimination Era (2004–2017): Estimates by Perspective and Cost Type

2020 ◽  
Vol 71 (6) ◽  
pp. 1568-1576
Author(s):  
Jamison Pike ◽  
Andrew J Leidner ◽  
Paul A Gastañaduy
Keyword(s):  
United States ◽  
Indirect Costs ◽  
Health Department ◽  
The United States ◽  
Public Health Department ◽  
Median Cost ◽  
Cost Estimates ◽  
Measles Outbreak ◽  
Measles Outbreaks ◽  
The Cost

Abstract Despite the elimination of measles in the United States (US) in the year 2000, cases continue to occur, with measles outbreaks having occurred in various jurisdictions in the US in 2018 and 2019. Understanding the cost associated with measles outbreaks can inform cost-of-illness and cost-effectiveness studies of measles and measles prevention. We performed a literature review and identified 10 published studies from 2001 through 2018 that presented cost estimates from 11 measles outbreaks. The median total cost per measles outbreak was $152 308 (range, $9862–$1 063 936); the median cost per case was $32 805 (range, $7396–$76 154) and the median cost per contact was $223 (range, $81–$746). There were limited data on direct and indirect costs associated with measles. These findings highlight how costly measles outbreaks can be, the value of this information for public health department budgeting, and the importance of more broadly documenting the cost of measles outbreaks.

scholarly journals Improved Temporal Trends of Vaccination Coverage Rates in Childhood after the Mandatory Vaccination Act, Italy 2014–2019

2021 ◽  
Vol 10 (12) ◽  
pp. 2540
Author(s):  
Michela Sabbatucci ◽  
Anna Odone ◽  
Carlo Signorelli ◽  
Andrea Siddu ◽  
Francesco Maraglino ◽  
...  
Keyword(s):  
Vaccine Coverage ◽  
Temporal Trends ◽  
Herd Immunity ◽  
Haemophilus Influenzae Type ◽  
Childhood Immunization ◽  
Vaccine Preventable Diseases ◽  
Immunization Rates ◽  
Health Strategy ◽  
Coverage Rates ◽  
The Impact

Maintaining high vaccine coverage (VC) for pediatric vaccinations is crucial to ensure herd immunity, reducing the risk of vaccine-preventable diseases (VPD). The Italian vaccination Law (n. 119/2017) reinforced mandates for polio, diphtheria, tetanus, and hepatitis B, extending the mandate to pertussis, Haemophilus influenzae type b, chickenpox, measles, mumps, and rubella, for children up to 16 years of age. We analyzed the national temporal trends of childhood immunization rates from 2014 to 2019 to evaluate the impact of the mandatory reinforcement law set in 2017 as a sustainable public health strategy in Italy. In a 3-year period, 9 of the 10 compulsory vaccinations reached the threshold of 95% and VC for chicken pox increased up to 90.5%, significantly. During the same period, the recommended vaccinations (against meningococcus B and C, pneumococcus, and rotavirus) also recorded a significant increase in VC trends. In conclusion, although the reinforcement of compulsory vaccination generated a wide public debate that was amplified by traditional and social media, the 3-year evaluation highlights positive results.

scholarly journals Measuring the Success of the US COVID-19 Vaccine Campaign—It’s Time to Invest in and Strengthen Immunization Information Systems

2021 ◽  
pp. e1-e3
Author(s):  
Jade Benjamin-Chung ◽  
Arthur Reingold
Keyword(s):  
Public Health ◽  
Information Systems ◽  
Vaccine Coverage ◽  
Herd Immunity ◽  
The United States ◽  
Time Estimates ◽  
The Us ◽  
Control And Prevention ◽  
Public Health Officials ◽  
State And Local

With the recent US Food and Drug Administration approval of the Pfizer-BioNTech and Moderna SARS-CoV-2 vaccines, the United States has begun COVID-19 vaccine dissemination. The vaccination program is historic in its massive scope and complexity. It requires accurate, real-time estimates of vaccine coverage to assess progress toward achieving herd immunity. Under Operation Warp Speed, the US Centers for Disease Control and Prevention (CDC) has constructed a federal database, or “data lake,” to monitor vaccine coverage nationwide and ensure that recipients receive both of the necessary doses. The data lake will be managed separately from existing state and local immunization information systems (IISs), which house vaccine data in all 50 states, five cities, the District of Columbia, and eight territories. In an open letter to the Director of the CDC in late 2020, four organizations representing immunization managers and public health officials expressed concerns about the plan to include vaccine recipients’ personal identifier information in the data lake.1 They also urged stronger coordination with IISs. (Am J Public Health. Published online ahead of print Feburary 18, 2021: e1–e3. https://doi.org/10.2105/AJPH.2021.306177 )

scholarly journals Public health practitioner perspectives on dealing with measles outbreaks if high anti-vaccination sentiment is present

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Penelope Robinson ◽  
Kerrie Wiley ◽  
Chris Degeling
Keyword(s):  
Public Health ◽  
Vaccination Schedule ◽  
Health Practitioner ◽  
Vaccine Preventable Diseases ◽  
Vaccination Rates ◽  
Modified Delphi ◽  
Global Pandemic ◽  
Measles Outbreak ◽  
High Level ◽  
Measles Outbreaks

Abstract Background Communities with low vaccination rates are at greater risk during outbreaks of vaccine preventable diseases. Most Australian parents support vaccines, but some refuse and are often judged harshly by their community, especially during an outbreak. We sought the perspectives of Australian public health experts on the key issues faced when managing a measles outbreak in an area with high anti-vaccination sentiment. Methods A measles outbreak scenario formed the basis of a 3-round modified Delphi process to identify key practitioner concerns in relation to parents/carers who don’t follow the recommended vaccination schedule. We surveyed a range of professionals in the field: policymakers, infectious disease experts, immunisation program staff, and others involved in delivering childhood vaccinations, to identify key priorities when responding to an outbreak in a community with low vaccination coverage. Results Findings indicate that responses to measles outbreaks in communities with high anti-vaccination sentiment are motivated by concerns about the potential for a much larger outbreak event. The highest operational priority is to isolate infected children. The two most highly ranked practical issues are mistrust from non-vaccinating members of the local region and combatting misinformation about vaccines. Trying to change minds of such individuals is not a priority during an outbreak, nor is vaccinating their children. Using media and social media to provide information about the outbreak and measures the public can take to limit the spread of the disease was a focus. Conclusions Our findings provide a deeper understanding of the challenges faced during an outbreak and priorities for communicating with communities where there is a high level of anti-vaccination sentiment. In the context of a global pandemic, the results of this study also have implications for managing public health responses to community transmission of SARS-CoV-2, as COVID-19 vaccines becomes widely available.

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