Accounting for the spread of vaccination behavior to optimize influenza vaccination programs.
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ABSTRACT:
SUBMITTER: Kahana D
PROVIDER: S-EPMC8177529 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundThe threat of avian influenza and the 2004-2005 influenza vaccine supply shortage in the United States have sparked a debate about optimal vaccination strategies to reduce the burden of morbidity and mortality caused by the influenza virus.Methods and findingsWe present a comparative analysis of two classes of suggested vaccination strategies: mortality-based strategies that target high-risk populations and morbidity-based strategies that target high-prevalence populations. Applying the methods of contact network epidemiology to a model of disease transmission in a large urban population, we assume that vaccine supplies are limited and then evaluate the efficacy of these strategies across a wide range of viral transmission rates and for two different age-specific mortality distributions. We find that the optimal strategy depends critically on the viral transmission level (reproductive rate) of the virus: morbidity-based strategies outperform mortality-based strategies for moderately transmissible strains, while the reverse is true for highly transmissible strains. These results hold for a range of mortality rates reported for prior influenza epidemics and pandemics. Furthermore, we show that vaccination delays and multiple introductions of disease into the community have a more detrimental impact on morbidity-based strategies than mortality-based strategies.ConclusionsIf public health officials have reasonable estimates of the viral transmission rate and the frequency of new introductions into the community prior to an outbreak, then these methods can guide the design of optimal vaccination priorities. When such information is unreliable or not available, as is often the case, this study recommends mortality-based vaccination priorities.
| S-EPMC1584413 | biostudies-literature
Project description:BackgroundThe unpredictable nature of the potentially devastating impact of 2009 pH1N1 influenza pandemic highlights the need for pandemic preparedness planning, where modeling studies could be most useful for simulations of possible future scenarios.MethodsA compartmental model with pre-symptomatic and asymptomatic influenza infections is proposed which incorporates age groups as well as intervention measures such as age-specific vaccination, in order to study spread of influenza in a community.ResultsWe derive the basic reproduction number and other effective reproduction numbers under various intervention measures. For illustration, we make use of the Pneumonia and Influenza (P&I) mortality data and vaccination data of the very young (age 0-2) and the very old (age > 64) during 2004-2005 Taiwan winter influenza season to fit our model and to compute the relevant reproduction numbers. The reproduction number for this winter flu season is estimated to be slightly above one (approximately 1.0001).ConclusionsComparatively large errors in fitting the P&I mortality data of the elderly (> 64) were observed shortly after winter school closings in January, which may indicate the impact of younger, more active age groups transmitting influenza to other age groups outside of the school settings; in particular, to the elderly in the households. Pre-symptomatic infections seemed to have little effect on the model fit, while asymptomatic infection by asymptomatic infectives has a more pronounced impact on the model fit for the elderly mortality, perhaps indicating a larger role in disease transmission by asymptomatic infection. Simulations indicate that the impact of vaccination on the disease incidence might not be fully revealed in the change (or the lack thereof) in the effective reproduction number with interventions, but could still be substantial. The estimated per contact transmission probability for susceptible elderly is significantly higher than that of any other age group, perhaps highlighting the vulnerability of the elderly due to close contacts with their caretakers from other age groups. The relative impact of targeting the very young and the very old for vaccination was weakened by their relative inactivity, thus giving evidence of the lack of impact of vaccinating these two groups on the overall transmissibility of the disease in the community. This further underscores the need for morbidity-based strategy to prevent elderly mortality.
| S-EPMC2876165 | biostudies-literature
Project description:BackgroundInfluenza vaccination is the most efficient and cost-effective method to prevent influenza. To increase vaccination coverage, health authorities use various intervention programs (IPs), such as cost subsidies or placing vaccination centers in malls to make vaccination more accessible. Nevertheless, vaccination coverage has been sub-optimal in most developed countries, including in Israel.MethodsTo determine possible drivers of individual vaccination uptake and to examine the effectiveness of different IPs in increasing vaccination, we analyzed a telephone survey of a representative sample of the Israeli population conducted in March 2011 (n?=?470), and paper questionnaires at the work place and at homes during April-July 2011 to several sub-populations : soldiers (n?=?81), medical staff (n?=?107), ultra-orthodox Jews (n?=?72), Israeli Arabs (n?=?87) and students (n?=?85).ResultsThe population can be stratified into three sub-groups: Acceptors, who receive vaccination regardless of IPs (22%), Conditional Acceptors, who are only vaccinated because of IP implementation (44%) and Non-Acceptors, who are not vaccinated despite IP implementation (34%). Our analysis shows that the risk perception towards influenza relative to vaccination is higher in the Acceptors than in the Conditional Acceptors, with the Non-Acceptors showing the lowest risk perception (P?<?0.01). For Conditional Acceptors, physician recommendation is the most effective IP, regardless of the sub-population tested (P?=?0.04). Students and low-income participants were more prone than any others to be persuaded to receive vaccination following IPs. In addition, financial incentives were more effective for ultra-religious orthodox Jews and students; vaccinations in more accessible areas were more effective for the ultra-religious orthodox, soldiers, and medical personnel; and TV and radio advertisements were more effective for people above 50 relative to other age groups.ConclusionsRisk perception of influenza and vaccination governs the likelihood of successful implementation of IPs. Policy makers in Israel should invest efforts to increase the knowledge regarding influenza and vaccination, and should apply specific interventions customized to the preferences and diverse perceptions among the Israeli sub-populations.
| S-EPMC4021634 | biostudies-literature
Project description:INTRODUCTION:While increasingly popular among mid- to large-size employers, using financial incentives to induce health behavior change among employees has been controversial, in part due to poor quality and generalizability of studies to date. Thus, fundamental questions have been left unanswered: To generate positive economic returns on investment, what level of incentive should be offered for any given type of incentive program and among which employees? METHODS:We constructed a novel modeling framework that systematically identifies how to optimize marginal return on investment from programs incentivizing behavior change by integrating commonly collected data on health behaviors and associated costs. We integrated "demand curves" capturing individual differences in response to any given incentive with employee demographic and risk factor data. We also estimated the degree of self-selection that could be tolerated: that is, the maximum percentage of already-healthy employees who could enroll in a wellness program while still maintaining positive absolute return on investment. In a demonstration analysis, the modeling framework was applied to data from 3000 worksite physical activity programs across the nation. RESULTS:For physical activity programs, the incentive levels that would optimize marginal return on investment ($367/employee/year) were higher than average incentive levels currently offered ($143/employee/year). Yet a high degree of self-selection could undermine the economic benefits of the program; if more than 17% of participants came from the top 10% of the physical activity distribution, the cost of the program would be expected to always be greater than its benefits. DISCUSSION:Our generalizable framework integrates individual differences in behavior and risk to systematically estimate the incentive level that optimizes marginal return on investment.
| S-EPMC4801226 | biostudies-literature
Project description:Neutrophils are amongst the first cells to respond to inflammation and infection. Although they play a key role in limiting the dissemination of pathogens, the study of their dynamic behavior in immune organs remains elusive. In this work, we characterized in vivo the dynamic behavior of neutrophils in the mouse popliteal lymph node (PLN) after influenza vaccination with UV-inactivated virus. To achieve this, we used an image-based systems biology approach to detect the motility patterns of neutrophils and to associate them to distinct actions. We described a prominent and rapid recruitment of neutrophils to the PLN following vaccination, which was dependent on the secretion of the chemokine CXCL1 and the alarmin molecule IL-1?. In addition, we observed that the initial recruitment occurred mainly via high endothelial venules located in the paracortical and interfollicular regions of the PLN. The analysis of the spatial-temporal patterns of neutrophil migration demonstrated that, in the initial stage, the majority of neutrophils displayed a patrolling behavior, followed by the formation of swarms in the subcapsular sinus of the PLN, which were associated with macrophages in this compartment. Finally, we observed using multiple imaging techniques, that neutrophils phagocytize and transport influenza virus particles. These processes might have important implications in the capacity of these cells to present viral antigens.
| S-EPMC6881817 | biostudies-literature
Project description:Background and objectivesInfluenza infection in transplant recipients is often associated with significant morbidity. Surveys were conducted in 1999 and 2009 to find out if the influenza vaccination practices in the U.S. transplant programs had changed over the past 10 years.Design, setting, participants, & measurementsIn 1999, a survey of the 217 United Network for Organ Sharing-certified kidney and kidney-pancreas transplant centers in the U.S. was conducted regarding their influenza vaccination practice patterns. A decade later, a second similar survey of 239 transplant programs was carried out.ResultsThe 2009 respondents, compared with 1999, were more likely to recommend vaccination for kidney (94.5% versus 84.4%, P = 0.02) and kidney-pancreas recipients (76.8% versus 48.5%, P < 0.001), family members of transplant recipients (52.5% versus 21.0%, P < 0.001), and medical staff caring for transplant patients (79.6% versus 40.7%, P < 0.001). Physicians and other members of the transplant team were more likely to have been vaccinated in 2009 compared with 1999 (84.2% versus 62.3% of physicians, P < 0.001 and 91.2% versus 50.3% of nonphysicians, P < 0.001).ConclusionsOur study suggests a greater adoption of the Centers for Disease Control and Prevention influenza vaccination guidelines by U.S. transplant programs in vaccinating solid-organ transplant recipients, close family contacts, and healthcare workers.
| S-EPMC2974405 | biostudies-literature
Project description:BackgroundStudies have noted variations in the cost-effectiveness of school-located influenza vaccination (SLIV), but little is known about how SLIV's cost-effectiveness may vary by targeted age group (e.g., elementary or secondary school students), or vaccine consent process (paper-based or web-based). Further, SLIV's cost-effectiveness may be impacted by its spillover effect on practice-based vaccination; prior studies have not addressed this issue.MethodsWe performed a cost-effectiveness analysis on two SLIV programs in upstate New York in 2015-2016: (a) elementary school SLIV using a stepped wedge design with schools as clusters (24 suburban and 18 urban schools) and (b) secondary school SLIV using a cluster randomized trial (16 suburban and 4 urban schools). The cost-per-additionally-vaccinated child (i.e., incremental cost-effectiveness ratio (ICER)) was estimated by dividing the incremental SLIV intervention cost by the incremental effectiveness (i.e., the additional number of vaccinated students in intervention schools compared to control schools). We performed deterministic analyses, one-way sensitivity analyses, and probabilistic analyses.ResultsThe overall effectiveness measure (proportion of children vaccinated) was 5.7 and 5.5 percentage points higher, respectively, in intervention elementary (52.8%) and secondary schools (48.2%) than grade-matched control schools. SLIV programs vaccinated a small proportion of children in intervention elementary (5.2%) and secondary schools (2.5%). In elementary and secondary schools, the ICER excluding vaccine purchase was $85.71 and $86.51 per-additionally-vaccinated-child, respectively. When additionally accounting for observed spillover impact on practice-based vaccination, the ICER decreased to $80.53 in elementary schools -- decreasing substantially in secondary schools. (to $53.40). These estimates were higher than the published practice-based vaccination cost (median = $25.50, mean = $45.48). Also, these estimates were higher than our 2009-2011 urban SLIV program mean costs ($65) due to additional costs for use of a new web-based consent system ($12.97 per-additionally-vaccinated-child) and higher project coordination costs in 2015-2016. One-way sensitivity analyses showed that ICER estimates were most sensitive to the SLIV effectiveness.ConclusionsSLIV raises vaccination rates and may increase practice-based vaccination in primary care practices. While these SLIV programs are effective, to be as cost-effective as practice-based vaccination our SLIV programs would need to vaccinate more students and/or lower the costs for consent systems and project coordination.Trial registrationClinicalTrials.gov NCT02227186 (August 25, 2014), updated NCT03137667 (May 2, 2017).
| S-EPMC6591987 | biostudies-literature
Project description:BackgroundDescription of the epidemiology of influenza is needed to inform influenza vaccination policy. Here we examined influenza virus circulation in countries in the Asia-Pacific region and compared the timing of seasonal epidemics with the timing of influenza vaccination.MethodsData were obtained from the World Health Organization (WHO) FluNet database for 2010-2017 for countries in the WHO Asia-Pacific region. Data from countries covering ≥5 consecutive seasons and ≥ 100 influenza positive cases per year were included. Median proportions of cases for each influenza virus type were calculated by country and season. The timing and amplitude of the epidemic peaks were determined by Fourier decomposition. Vaccination timing was considered appropriate for each country if it was recommended ≤4 months before the primary peak of influenza circulation.ResultsSeven hundred eleven thousand seven hundred thirty-four influenza cases were included from 19 countries. Peak circulation coincided with the winter seasons in most countries, although patterns were less clear in some countries in the inter-tropical area due to substantial secondary peaks. Influenza A/H3N2 dominated overall, but proportions of A and B strains varied by year and by country. Influenza B represented 31.4% of all cases. The WHO-recommended timing for influenza vaccination was appropriate in 12 countries. Vaccination timing recommendations were considered inappropriate in Laos, Cambodia, and Thailand, and were inconclusive for India, Sri Lanka, Singapore, and Vietnam due to unclear seasonality of influenza virus circulation.ConclusionsInfluenza virus circulation varied considerably across the Asia-Pacific region with an unusually high burden of influenza B. The recommended timing for vaccination was appropriate in most countries, except for several countries with unclear seasonality, mainly located in the inter-tropical area.
| S-EPMC6429768 | biostudies-literature
Project description:BackgroundStudies have reported that prior-season influenza vaccination is associated with higher risk of clinical influenza infection among vaccinees in a given season. Understanding the underlying causes requires consideration of within-season waning and recent infection.MethodsUsing the US Flu Vaccine Effectiveness (VE) Network data over 8 influenza seasons (2011-2012 to 2018-2019), we estimated the effect of prior-season vaccination on the odds of clinical infection in a given season, after accounting for waning vaccine protection using regression methods. We adjusted for potential confounding by recent clinical infection using inverse-probability weighting. We investigated theoretically whether unmeasured subclinical infection in the prior season, which is more likely in the non-repeat vaccinees, could explain the repeat vaccination effect.ResultsRepeat vaccinees vaccinated earlier in a season by one week. After accounting for waning VE, repeat vaccinees were still more likely to test positive for influenza A(H3N2) (OR=1.11, 95% CI:1.02-1.21) but not for influenza B (OR=1.03, 95% CI:0.89-1.18) or A(H1N1) (OR=1.03, 95% CI:0.90-1.19) compared to those vaccinated in the given season only. Recent clinical infection with the homologous (sub)type protected against clinical infection with A(H3N2) or B. Individuals with clinical infection in one season had 1.11 (95% CI:1.03-1.19) times the odds of switching vaccination status in the following season. Adjusting for recent clinical infections did not strongly influence the estimated effect of prior-season vaccination. Adjusting for subclinical infection could theoretically attenuate this effect.ConclusionWaning protection and recent clinical infection were insufficient to explain observed reduced VE in repeat vaccinees with a test-negative design.
| S-EPMC10071822 | biostudies-literature
Project description:BackgroundInfluenza vaccine hesitancy is a significant threat to global efforts to reduce the burden of seasonal and pandemic influenza. Potential barriers of influenza vaccination need to be identified to inform interventions to raise awareness, influenza vaccine acceptance and uptake.ObjectiveThis review aims to (1) identify relevant studies and extract individual barriers of seasonal and pandemic influenza vaccination for risk groups and the general public; and (2) map knowledge gaps in understanding influenza vaccine hesitancy to derive directions for further research and inform interventions in this area.MethodsThirteen databases covering the areas of Medicine, Bioscience, Psychology, Sociology and Public Health were searched for peer-reviewed articles published between the years 2005 and 2016. Following the PRISMA approach, 470 articles were selected and analyzed for significant barriers to influenza vaccine uptake or intention. The barriers for different risk groups and flu types were clustered according to a conceptual framework based on the Theory of Planned Behavior and discussed using the 4C model of reasons for non-vaccination.ResultsMost studies were conducted in the American and European region. Health care personnel (HCP) and the general public were the most studied populations, while parental decisions for children at high risk were under-represented. This study also identifies understudied concepts. A lack of confidence, inconvenience, calculation and complacency were identified to different extents as barriers to influenza vaccine uptake in risk groups.ConclusionMany different psychological, contextual, sociodemographic and physical barriers that are specific to certain risk groups were identified. While most sociodemographic and physical variables may be significantly related to influenza vaccine hesitancy, they cannot be used to explain its emergence or intensity. Psychological determinants were meaningfully related to uptake and should therefore be measured in a valid and comparable way. A compendium of measurements for future use is suggested as supporting information.
| S-EPMC5268454 | biostudies-literature