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

2020 ◽  
Vol 7 (3) ◽  
Author(s):  
Romain Garnier ◽  
Emma R Nedell ◽  
Saad B Omer ◽  
Shweta Bansal
Keyword(s):  
Clustering Analysis ◽  
Vaccine Coverage ◽  
Herd Immunity ◽  
State Level ◽  
The United States ◽  
Childhood Vaccination ◽  
Policy Changes ◽  
Vaccination Rates ◽  
Exemption Policy ◽  
Epidemiological Effects

Abstract 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.

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 Impact of SARS-CoV-2 Vaccines on Covid-19 Incidence and Mortality in the United States

2021 ◽  
Author(s):  
Fang Fang ◽  
John David Clemens ◽  
Zuo-Feng Zhang ◽  
Timothy F. Brewer
Keyword(s):  
Negative Binomial ◽  
Herd Immunity ◽  
The United States ◽  
Vaccination Rate ◽  
Vaccine Hesitancy ◽  
Percentage Increase ◽  
Protective Effects ◽  
Vaccination Rates ◽  
Incidence And Mortality ◽  
Before And After

Background: Despite safe and effective vaccines to prevent Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) infections and disease, a substantial minority of the US remains resistant to getting vaccinated. It is imperative to know if expanding vaccination rates could reduce community-wide Coronavirus 2019 (COVID-19) disease, not just among those vaccinated. Methods: Negative binomial models were used to estimate associations between U.S. county-level vaccination rates and county-wide COVID-19 incidence and mortality between April 23rd and September 30th, 2021. A two-week lag and a four-week lag were introduced to assess vaccination rate impact on incidence and mortality, respectively. Stratified analyses were performed for county vaccination rates >40%, and before and after Delta became the dominant variant. Findings: Among 3,070 counties, each percentage increase in population vaccination rates reduced county-wide COVID-19 incidence by 0.9% (relative risk (RR) 0.9910 (95% CI: 0.9869, 0.9952)) and mortality by 1.9% (RR 0.9807 (95% CI: 0.9745, 0.9823)). Among counties with vaccination coverage >40%, each percentage increase in vaccination rates reduced COVID-19 disease by 1.5%, RR 0.9850 (95% CI: 0.9793, 0.9952) and mortality by 2.7% (RR 0.9727 (95% CI: 0.9632, 0.9823)). These associations were not observed among counties with <40% vaccination rates. Increasing vaccination rates from 40% to 80% would have reduced COVID-19 cases by 45.4% (RR 0.5458 (95% CI: 0.4335, 0.6873)) and deaths by 67.0% (RR 0.3305 (95% CI: 0.2230, 0.4898)). An estimated 5,989,952 COVID-19 cases could have been prevented and 127,596 lives saved had US population vaccination rates increased from 40% to 80%. Interpretations: Increasing U.S. SARS-CoV-2 vaccination rates results in population-wide reductions in COVID-19 incidence and mortality. Furthermore, increasing vaccination rates above 40% has protective effects among non-vaccinated persons. Given ongoing vaccine hesitancy in the U.S., increasing vaccination rates could better protect the entire community and potentially reach herd immunity. Funding: National Cancer Institute

scholarly journals The Effect of Vaccination Rates on the Infection of COVID-19 under the Vaccination Rate below the Herd Immunity Threshold

2021 ◽  
Vol 18 (14) ◽  
pp. 7491
Author(s):  
Yi-Tui Chen
Keyword(s):  
Infection Rate ◽  
Herd Immunity ◽  
The United States ◽  
Vaccination Rate ◽  
Infection Rates ◽  
Vaccination Rates ◽  
The United Kingdom ◽  
The World ◽  
Almost All ◽  
The Impact

Although vaccination is carried out worldwide, the vaccination rate varies greatly. As of 24 May 2021, in some countries, the proportion of the population fully vaccinated against COVID-19 has exceeded 50%, but in many countries, this proportion is still very low, less than 1%. This article aims to explore the impact of vaccination on the spread of the COVID-19 pandemic. As the herd immunity of almost all countries in the world has not been reached, several countries were selected as sample cases by employing the following criteria: more than 60 vaccine doses per 100 people and a population of more than one million people. In the end, a total of eight countries/regions were selected, including Israel, the UAE, Chile, the United Kingdom, the United States, Hungary, and Qatar. The results find that vaccination has a major impact on reducing infection rates in all countries. However, the infection rate after vaccination showed two trends. One is an inverted U-shaped trend, and the other is an L-shaped trend. For those countries with an inverted U-shaped trend, the infection rate begins to decline when the vaccination rate reaches 1.46–50.91 doses per 100 people.

scholarly journals Improving the accuracy of ACIR data and increasing vaccination rates

2019 ◽  
Vol 43 ◽  
Author(s):  
Thaïs A Miles ◽  
Linda V Granger ◽  
Colleen L Gately
Keyword(s):  
Public Health ◽  
Quality Improvement ◽  
Vaccine Coverage ◽  
Health Unit ◽  
Quality Improvement Activity ◽  
Childhood Immunisation ◽  
Central Coast ◽  
Vaccine Preventable Diseases ◽  
Vaccination Rates

Immunisation at the earliest appropriate age and high levels of vaccine coverage at milestone ages are important in preventing the spread of vaccine-preventable diseases. At the Central Coast Public Health Unit, the authors sought to determine if follow-up of children said by the Australian Childhood Immunisation Register (ACIR) to be overdue for vaccination improved both of these factors. In a quality improvement activity, monthly ACIR lists of overdue Central Coast children aged 9 to 10 months of age were examined. The study alternated three months of intervention with three months of no intervention. The intervention was designed to find evidence of vaccination, first from the last known provider, and then if this was unsuccessful, from the parent. If no information was available, a letter was sent to the parents. If the child was indeed vaccinated, the register was updated. If the child was missing any vaccinations, the parent(s) were encouraged to complete the schedule. On reviewing routinely-published quarterly ACIR data at three-monthly intervals for 24 months after the intervention (or non-intervention), timeliness of vaccination improved in the intervention cohort. Central Coast fully vaccinated rates diverged from NSW rates during the study. In addition, the ACIR quarters that contained two out of three months of intervention rather than one out of three months of intervention had the highest rates of fully vaccinated children. The authors concluded that the intervention improved both timeliness of vaccination and the proportion of fully vaccinated children.

scholarly journals Modeling the COVID-19 Vaccination Dynamics in the United States: An Estimation of Coverage Velocity and Carrying Capacity Based on Socio-demographic Vulnerability Indices in California

2021 ◽  
Author(s):  
Alexander Bruckhaus ◽  
Aidin Abedi ◽  
Sana Salehi ◽  
Trevor A Pickering ◽  
Yujia Zhang ◽  
...  
Keyword(s):  
Vaccine Coverage ◽  
Vulnerability Index ◽  
The United States ◽  
Household Composition ◽  
Social Vulnerability Index ◽  
Vaccination Rates ◽  
Group Methods ◽  
The Social ◽  
Data Points ◽  
Maximum Proportion

Introduction: Coronavirus disease 2019 (COVID-19) disparities among vulnerable populations are a paramount concern that extends to COVID-19 vaccine administration. We aim to better characterize the scope of vaccine inequity in California by comparing the Social Vulnerability Index (SVI) of California counties and respective vaccination rates, modeling the growth rate and anticipated maximum proportion of individuals vaccinated by SVI group. Methods: Overall SVI, its four themes, and 9228 data points of daily vaccination numbers across all 58 California counties were used to model, overall and by theme, growth velocity of proportion of population vaccinated and the expected maximum proportion of individuals (at least 1 dose of Pfizer-BioNTech, Moderna, or Johnson & Johnson/Janssen) that will be vaccinated for each theme. Results: Overall high vulnerability counties in California have lower vaccine coverage velocity compared to low and moderate vulnerability counties. The largest disparity in coverage velocity between low and highly vulnerable counties was observed in Theme 3 (minority status & language). However, our model showed that highly vulnerable counties based on Theme 3 are expected to eventually achieve a higher proportion of vaccinated individuals compared to low vulnerable counterparts if current trajectories continue. Counties in the overall low vulnerability category are estimated to achieve a higher proportion of vaccinated individuals when compared to high and moderate vulnerable counties, assuming current trajectories. The largest disparity in asymptotic proportion vaccinated between high and low vulnerable counties was observed in Theme 2 (household composition & disability). Conclusion: This study provides insight into the problem of COVID-19 vaccine disparity across California which can be used to help promote equity during the current pandemic as well as guide the allocation of future vaccines such as COVID-19 booster shots.

scholarly journals Demographics, perceptions, and socioeconomic factors affecting influenza vaccination among adults in the United States

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5171 ◽  
Author(s):  
Kaja M. Abbas ◽  
Gloria J. Kang ◽  
Daniel Chen ◽  
Stephen R. Werre ◽  
Achla Marathe
Keyword(s):  
United States ◽  
Health Insurance ◽  
Influenza Vaccination ◽  
Vaccine Efficacy ◽  
Herd Immunity ◽  
The United States ◽  
Vaccine Cost ◽  
Factors Affecting ◽  
Vaccination Rates ◽  
Healthy People 2020

Objective The study objective is to analyze influenza vaccination status by demographic factors, perceived vaccine efficacy, social influence, herd immunity, vaccine cost, health insurance status, and barriers to influenza vaccination among adults 18 years and older in the United States. Background Influenza vaccination coverage among adults 18 years and older was 41% during 2010–2011 and has increased and plateaued at 43% during 2016–2017. This is below the target of 70% influenza vaccination coverage among adults, which is an objective of the Healthy People 2020 initiative. Methods We conducted a survey of a nationally representative sample of adults 18 years and older in the United States on factors affecting influenza vaccination. We conducted bivariate analysis using Rao-Scott chi-square test and multivariate analysis using weighted multinomial logistic regression of this survey data to determine the effect of demographics, perceived vaccine efficacy, social influence, herd immunity, vaccine cost, health insurance, and barriers associated with influenza vaccination uptake among adults in the United States. Results Influenza vaccination rates are relatively high among adults in older age groups (73.3% among 75 + year old), adults with education levels of bachelor’s degree or higher (45.1%), non-Hispanic Whites (41.8%), adults with higher incomes (52.8% among adults with income of over $150,000), partnered adults (43.2%), non-working adults (46.2%), and adults with internet access (39.9%). Influenza vaccine is taken every year by 76% of adults who perceive that the vaccine is very effective, 64.2% of adults who are socially influenced by others, and 41.8% of adults with health insurance, while 72.3% of adults without health insurance never get vaccinated. Facilitators for adults getting vaccinated every year in comparison to only some years include older age, perception of high vaccine effectiveness, higher income and no out-of-pocket payments. Barriers for adults never getting vaccinated in comparison to only some years include lack of health insurance, disliking of shots, perception of low vaccine effectiveness, low perception of risk for influenza infection, and perception of risky side effects. Conclusion Influenza vaccination rates among adults in the United States can be improved towards the Healthy People 2020 target of 70% by increasing awareness of the safety, efficacy and need for influenza vaccination, leveraging the practices and principles of commercial and social marketing to improve vaccine trust, confidence and acceptance, and lowering out-of-pocket expenses and covering influenza vaccination costs through health insurance.

scholarly journals Status of Vaccine Coverage In Venezuelan Children, A Country With A Complex Humanitarian Crisis

2020 ◽  
Author(s):  
Tatiana Drummond ◽  
Isabel Marín ◽  
Anny Sánchez ◽  
Marianjosé Reyes ◽  
Jenny García ◽  
...  
Keyword(s):  
Vaccination Coverage ◽  
Vaccine Coverage ◽  
Immunization Coverage ◽  
Cross Sectional Study ◽  
Vaccination Schedule ◽  
Humanitarian Crisis ◽  
Cross Sectional ◽  
Vaccine Preventable Diseases ◽  
Vaccination Rates ◽  
One Year

Abstract In Venezuela, PAHO has reported an increase in vaccine-preventable diseases since 2016. The goal of this work was to assess vaccination coverage in children hospitalized in the Department of Pediatrics at the Hospital Universitario de Caracas (HUC). Methods: A descriptive cross-sectional study included 0 to 12 years old children hospitalized in HUC admitted between January 2015 and December 2019, and verified immunization scheme. The patient data were compared with the schedule of the Ministry of Health of Venezuela and analyzed by comparing immunization coverage by year of patient hospitalization and patient age. Results: A total of 2903 patients were surveyed, corresponding to 53.2% male, 37.4% infants. A coverage level above 95% was found only for BCG. Comparing vaccination coverage with the vaccination schedule vs year of patient hospitalization, it was observed a mean decrease in vaccine coverage of 21.5% in 2019 relative to 2015 (p = 0.0000). Vaccination rates in children under one year old were lower than in children older than 6 years for all vaccines (p = 0.0000) Conclusions: There is a decline in vaccination coverage in 2019 in relation to previous years, being the most affected children less than one year old

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 Vaccine-Induced Cellular Immunity against Bordetella pertussis: Harnessing Lessons from Animal and Human Studies to Improve Design and Testing of Novel Pertussis Vaccines

Vaccines ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 877
Author(s):  
Anja Saso ◽  
Beate Kampmann ◽  
Sophie Roetynck
Keyword(s):  
Whooping Cough ◽  
Vaccine Coverage ◽  
Current Knowledge ◽  
Herd Immunity ◽  
Cell Mediated Immunity ◽  
Improve Design ◽  
Vaccine Preventable Diseases ◽  
Key Factor ◽  
Cellular Immune ◽  
Design And Testing

Pertussis (‘whooping cough’) is a severe respiratory tract infection that primarily affects young children and unimmunised infants. Despite widespread vaccine coverage, it remains one of the least well-controlled vaccine-preventable diseases, with a recent resurgence even in highly vaccinated populations. Although the exact underlying reasons are still not clear, emerging evidence suggests that a key factor is the replacement of the whole-cell (wP) by the acellular pertussis (aP) vaccine, which is less reactogenic but may induce suboptimal and waning immunity. Differences between vaccines are hypothesised to be cell-mediated, with polarisation of Th1/Th2/Th17 responses determined by the composition of the pertussis vaccine given in infancy. Moreover, aP vaccines elicit strong antibody responses but fail to protect against nasal colonisation and/or transmission, in animal models, thereby potentially leading to inadequate herd immunity. Our review summarises current knowledge on vaccine-induced cellular immune responses, based on mucosal and systemic data collected within experimental animal and human vaccine studies. In addition, we describe key factors that may influence cell-mediated immunity and how antigen-specific responses are measured quantitatively and qualitatively, at both cellular and molecular levels. Finally, we discuss how we can harness this emerging knowledge and novel tools to inform the design and testing of the next generation of improved infant pertussis vaccines.

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