Evaluating Partial Series Childhood Vaccination Services in a Mobile Clinic Setting.

This study aims to evaluate the cost-benefit of vaccination services, mostly partial series administration, provided by a mobile clinic program (MCP) in Houston for children of transient and low-income families. The study included 469 patients who visited the mobile clinics on regular service days in 2 study periods in 2014 and 836 patients who attended vaccination events in the summer of 2014. The benefit of partial series vaccination was estimated based on vaccine efficacy/effectiveness data. Our conservative cost-benefit estimates show that, compared with office-based settings, every dollar spent on vaccination by the MCP would result in $0.9 societal cost averted as an incremental benefit in regular service days and $3.7 during vaccination-only events. To further improve the cost-benefit of vaccination services in the MCP, decision-makers and stakeholders may consider improving work efficiency during regular service days or hosting more vaccination events.

Evaluation of non-continuous temperature monitoring practices for vaccine storage units: A Monte Carlo simulation study.

Objectives: Evaluate different non-continuous temperature monitoring practices for detection of out-of-range temperatures (above or below the recommended temperature range of 2-8°C for refrigeration units), which are called excursions, within vaccine storage units. Methods: Simulations based on temperature data collected by 243 digital data loggers operated in vaccine storage units at health care providers who participated in a CDC-sponsored continuous temperature monitoring pilot project, from 2012 to 2015. In the primary analysis, we evaluate: (1) twice-daily current temperature readings without minimum and maximum readings (min/max), (2) twice-daily current temperature readings with once-daily min/max, and (3) twice-daily current temperature readings with twice-daily min/max. Results: Recording current temperature twice-daily without min/max resulted in the detection of 4.8-6.4% of the total number of temperature excursions. When min/max readings were introduced, the percentage of detected temperature excursions increased to 27.8-96.6% with once-daily min/max and to 34.8-96.7% with twice-daily min/max. Conclusions: Including min/max readings improves the ability of a temperature monitoring practice to detect temperature excursions. No combination of the non-continuous temperature monitoring practices were able to consistently detect all simulated temperature excursions.

Use of a choice survey to identify adult, adolescent and parent preferences for vaccination in the United States.

BACKGROUND: Adult and adolescent vaccination rates are far below coverage targets in the United States. Our objective was to identify the most influential factors related to vaccine uptake among adults, adolescents, and parents of adolescents (parents) in the United States. METHODS: We used a fractional factorial design to create a binary choice survey to evaluate preferences for vaccination. The national survey was fielded to a sample of adults, adolescents ages 13-17 years, and parents, using a national probability-based online research panel in November 2015. Respondents were presented with 5 profiles of a hypothetical vaccine and asked in a series of questions whether they would accept each vaccine. We analyzed the binary choice data using logistic regression in STATA v13 (College Station, TX) to calculate the odds that a participant would choose to accept the vaccine. RESULTS: We received completed responses from 334 (51%) of 652 adults, 316 (21%) of 1516 adolescents, and 339 (33%) of 1030 parents. Respondents were generally representative of the U.S. POPULATION: Vaccine effectiveness was the most influential factor in the choice to vaccinate for all groups. Other most influential factors were primary care provider (PCP) recommendation and the out-of-pocket cost of the vaccine. Other factors such as risk of illness, risk of vaccine side effects, vaccination location, and time for vaccination were not important in the decision to get vaccinated. CONCLUSIONS: Adults, adolescents, and parents are most sensitive to vaccine effectiveness, PCP recommendation, and out-of-pocket cost for vaccination in their decision to get vaccinated. Strong PCP recommendations that focus on vaccine effectiveness and health care policies that minimize out-of-pocket costs for vaccinations may increase vaccine uptake by adults and adolescents.

Preferences for health economics presentations among vaccine policymakers and researchers.

PURPOSE: Measure the preferences of decision makers and researchers associated with the Advisory Committee on Immunization Practices (ACIP) regarding the recommended format for presenting health economics studies to the ACIP. METHODS: We conducted key informant interviews and an online survey of current ACIP work group members, and current and previous ACIP voting members, liaison representatives, and ex-officio members to understand preferences for health economics presentations. These preferences included the presentation of results and sensitivity analyses, the role of health economics studies in decision making, and strategies to improve guidelines for presenting health economics studies. Best-worst scaling was used to measure the relative value of seven attributes of health economics presentations in vaccine decision making. RESULTS: The best-worst scaling survey had a response rate of 51% (n = 93). Results showed that summary results were the most important attribute for decision making (mean importance score: 0.69) and intermediate outcomes and disaggregated results were least important (mean importance score: -0.71). Respondents without previous health economics experience assigned sensitivity analysis lower importance and relationship of the results to other studies higher importance than the experienced group (sensitivity analysis scores: -0.15 vs. 0.15 respectively; relationship of the results: 0.13 vs. -0.12 respectively). Key informant interviews identified areas for improvement to include additional information on the quality of the analysis and increased role for liaisons familiar with health economics. CONCLUSION: Additional specificity in health economics presentations could allow for more effective presentations of evidence for vaccine decision making.

Factors associated with the pricing of childhood vaccines in the U.S. public sector.

Vaccine purchase cost has grown substantially over the last few decades. A closer look at vaccine prices reveals that not all vaccines shared the same increasing pattern. Various factors, such as vaccine attributes, competition, and supply shortages, could relate to price changes. In this study, we examined whether a variety of factors influenced the prices of noninfluenza childhood vaccines purchased in the public sector from 1996 to 2014. The association differed among price-capped vaccines and combination vaccines. There was an increasing time trend in real prices for non-price-capped vaccines, which was mostly offset by the effect of market longevity. The effect of competition in lowering prices was more pronounced among non-price-capped vaccines when manufacturer and vaccine component fixed effects were excluded. Supply shortage, manufacturer name change, and number of vaccine doses in series showed no effect. The results may help policy makers better understand price behaviors and make more informed decisions in vaccine planning and financing.

School-Based Influenza Vaccination: Health and Economic Impact of Maine's 2009 Influenza Vaccination Program.

OBJECTIVE: To estimate the societal economic and health impacts of Maine's school-based influenza vaccination (SIV) program during the 2009 A(H1N1) influenza pandemic. DATA SOURCES: Primary and secondary data covering the 2008-09 and 2009-10 influenza seasons. STUDY DESIGN: We estimated weekly monovalent influenza vaccine uptake in Maine and 15 other states, using difference-in-difference-in-differences analysis to assess the program's impact on immunization among six age groups. We also developed a health and economic Markov microsimulation model and conducted Monte Carlo sensitivity analysis. DATA COLLECTION: We used national survey data to estimate the impact of the SIV program on vaccine coverage. We used primary data and published studies to develop the microsimulation model. PRINCIPAL FINDINGS: The program was associated with higher immunization among children and lower immunization among adults aged 18-49 years and 65 and older. The program prevented 4,600 influenza infections and generated $4.9 million in net economic benefits. Cost savings from lower adult vaccination accounted for 54 percent of the economic gain. Economic benefits were positive in 98 percent of Monte Carlo simulations. CONCLUSIONS: SIV may be a cost-beneficial approach to increase immunization during pandemics, but programs should be designed to prevent lower immunization among nontargeted groups.

Trends in childhood vaccine purchase costs in the US public sector: 1996-2014.

While vaccination remains as one of the most cost-effective preventive strategies, the cost of fully immunizing a child has grown considerably over the last few decades. This study examines trends in non-influenza childhood vaccine purchase costs in the public sector from 1996 to 2014. Non-influenza vaccine purchase cost per child for children aged 0 through 18years was calculated based on public-sector purchase prices. Purchase cost changes were then decomposed into changes attributable to recommendation updates and changes attributable to price variation. The study analyzed the growth rate of combination vaccine prices separately and compared these prices with the sum of prices of component vaccines. It is found that the average annual growth rate of non-influenza vaccine purchase cost per child during 1996-2014 was 12.6%. The growth rate attributable to price changes was 1.0% on average. Combination vaccine prices showed greater variation. The study concludes that vaccine price variation was one but a minor reason for purchase cost changes. Recommendation updates, particularly the introduction of new vaccines, played a much larger role in raising the purchase costs. If the 12.6% annual growth rate found during 1996-2014 in the study continues to apply, the purchase costs of childhood vaccines may more than double by 2020.

Hitting the Optimal Vaccination Percentage and the Risks of Error: Why to Miss Right.

OBJECTIVE: To determine the optimal level of vaccination coverage defined as the level that minimizes total costs and explore how economic results change with marginal changes to this level of coverage. METHODS: A susceptible-infected-recovered-vaccinated model designed to represent theoretical infectious diseases was created to simulate disease spread. Parameter inputs were defined to include ranges that could represent a variety of possible vaccine-preventable conditions. Costs included vaccine costs and disease costs. Health benefits were quantified as monetized quality adjusted life years lost from disease. Primary outcomes were the number of infected people and the total costs of vaccination. Optimization methods were used to determine population vaccination coverage that achieved a minimum cost given disease and vaccine characteristics. Sensitivity analyses explored the effects of changes in reproductive rates, costs and vaccine efficacies on primary outcomes. Further analysis examined the additional cost incurred if the optimal coverage levels were not achieved. RESULTS: Results indicate that the relationship between vaccine and disease cost is the main driver of the optimal vaccination level. Under a wide range of assumptions, vaccination beyond the optimal level is less expensive compared to vaccination below the optimal level. This observation did not hold when the cost of the vaccine cost becomes approximately equal to the cost of disease. DISCUSSION AND CONCLUSION: These results suggest that vaccination below the optimal level of coverage is more costly than vaccinating beyond the optimal level. This work helps provide information for assessing the impact of changes in vaccination coverage at a societal level.

Cost-effectiveness of seasonal inactivated influenza vaccination among pregnant women.

OBJECTIVE: To evaluate the cost-effectiveness of seasonal inactivated influenza vaccination among pregnant women using data from three recent influenza seasons in the United States. DESIGN, SETTING, AND PARTICIPANTS: We developed a decision-analytic model following a cohort of 5.2 million pregnant women and their infants aged <6 months to evaluate the cost-effectiveness of vaccinating women against seasonal influenza during pregnancy from a societal perspective. The main outcome measures were quality-adjusted life-year (QALY) gained and cost-effectiveness ratios. Data sources included surveillance data, epidemiological studies, and published vaccine cost data. Sensitivity analyses were also performed. All costs and outcomes were discounted at 3% annually. MAIN OUTCOME MEASURES: Total costs (direct and indirect), effects (QALY gains, averted case numbers), and incremental cost-effectiveness of seasonal inactivated influenza vaccination among pregnant women (cost per QALY gained). RESULTS: Using a recent benchmark of 52.2% vaccination coverage among pregnant women, we studied a hypothetical cohort of 2,753,015 vaccinated pregnant women. With an estimated vaccine effectiveness of 73% among pregnant women and 63% among infants <6 months, QALY gains for each season were 305 (2010-2011), 123 (2011-2012), and 610 (2012-2013). Compared with no vaccination, seasonal influenza vaccination during pregnancy was cost-saving when using data from the 2010-2011 and 2012-2013 influenza seasons. The cost-effectiveness ratio was greater than $100,000/QALY with the 2011-2012 influenza season data, when CDC reported a low attack rate compared to other recent seasons. CONCLUSIONS: Influenza vaccination for pregnant women can reduce morbidity from influenza in both pregnant women and their infants aged <6 months. Seasonal influenza vaccination during pregnancy is cost-saving during moderate to severe influenza seasons.

Impact and cost-effectiveness of a second tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine dose to prevent pertussis in the United States.

INTRODUCTION: The United States experienced a substantial increase in reported pertussis cases over the last decade. Since 2005, persons 11 years and older have been routinely recommended to receive a single dose of tetanus toxoid, reduced diphtheria toxoid and acellular pertussis (Tdap) vaccine. The objective of this analysis was to evaluate the potential impact and cost-effectiveness of recommending a second dose of Tdap. METHODS: A static cohort model was used to calculate the epidemiologic and economic impact of adding a second dose of Tdap at age 16 or 21 years. Projected costs and outcomes were examined from a societal perspective over a 20-year period. Quality-adjusted Life Years (QALY) saved were calculated. RESULTS: Using baseline pertussis incidence from the National Notifiable Diseases Surveillance System, Tdap revaccination at either age 16 or 21 years would reduce outpatient visits by 433 (5%) and 285 (4%), and hospitalization cases by 7 (7%) and 5 (5%), respectively. The costs per QALY saved with a second dose of Tdap were approximately US $19.7 million (16 years) and $26.2 million (21 years). In sensitivity analyses, incidence most influenced the model; as incidence increased, the costs per QALY decreased. To a lesser degree, initial vaccine effectiveness and waning of effectiveness also affected cost outcomes. Multivariate sensitivity analyses showed that under a set of optimistic assumptions, the cost per QALY saved would be approximately $163,361 (16 years) and $204,556 (21 years). CONCLUSION: A second dose of Tdap resulted in a slight decrease in the number of cases and other outcomes, and that trend is more apparent when revaccinating at age 16 years than at age 21 years. Both revaccination strategies had high dollar per QALY saved even under optimistic assumptions in a multivariate sensitivity analysis.

Adolescent girls' preferences for HPV vaccines: a discrete choice experiment.

PURPOSE: To measure adolescent girls' preferences over features of human papillomavirus (HPV) vaccines in order to provide quantitative estimates of the perceived benefits of vaccination and potential vaccine uptake. DESIGN/METHODOLOGY/APPROACH: A discrete choice experiment (DCE) survey was developed to measure adolescent girls' preferences over features of HPV vaccines. The survey was fielded to a U.S. sample of 307 girls aged 13-17 years who had not yet received an HPV vaccine in June 2008. FINDINGS: In a latent class logit model, two distinct groups were identified--one with strong preferences against vaccination which largely did not differentiate between vaccine features, and another that was receptive to vaccination and had well-defined preferences over vaccine features. Based on the mean estimates over the entire sample, we estimate that girls' valuation of bivalent and quadrivalent HPV vaccines ranged between $400 and $460 in 2008, measured as willingness-to-pay (WTP). The additional value of genital warts protection was $145, although cervical cancer efficacy was the most preferred feature. We estimate maximum uptake of 54-65%, close to the 53% reported for one dose in 2011 surveillance data, but higher than the 35% for three doses in surveillance data. RESEARCH LIMITATIONS/IMPLICATIONS: We conclude that adolescent girls do form clear opinions and some place significant value on HPV vaccination, making research on their preferences vital to understanding the determinants of HPV vaccine demand. ORIGINALITY/VALUE: DCE studies may be used to design more effective vaccine-promotion programs and for reassessing public health recommendations and guidelines as new vaccines are made available.

Economic evaluation of the routine childhood immunization program in the United States, 2009.

OBJECTIVES: To evaluate the economic impact of the 2009 routine US childhood immunization schedule, including diphtheria and tetanus toxoids and acellular pertussis, Haemophilus influenzae type b conjugate, inactivated poliovirus, measles/mumps/rubella, hepatitis B, varicella, 7-valent pneumococcal conjugate, hepatitis A, and rotavirus vaccines; influenza vaccine was not included. METHODS: Decision analysis was conducted using population-based vaccination coverage, published vaccine efficacies, historical data on disease incidence before vaccination, and disease incidence reported during 2005 to 2009. Costs were estimated using the direct cost and societal (direct and indirect costs) perspectives. Program costs included vaccine, administration, vaccine-associated adverse events, and parent travel and work time lost. All costs were inflated to 2009 dollars, and all costs and benefits in the future were discounted at a 3% annual rate. A hypothetical 2009 US birth cohort of 4,261,494 infants over their lifetime was followed up from birth through death. Net present value (net savings) and benefit-cost ratios of routine childhood immunization were calculated. RESULTS: Analyses showed that routine childhood immunization among members of the 2009 US birth cohort will prevent ∼42,000 early deaths and 20 million cases of disease, with net savings of $13.5 billion in direct costs and $68.8 billion in total societal costs, respectively. The direct and societal benefit-cost ratios for routine childhood vaccination with these 9 vaccines were 3.0 and 10.1. CONCLUSIONS: From both direct cost and societal perspectives, vaccinating children as recommended with these vaccines results in substantial cost savings.

Parent attitudes about school-located influenza vaccination clinics.

The use of alternative venues beyond physician offices may help to increase rates of population influenza vaccination. Schools provide a logical setting for reaching children, but most school-located vaccination (SLV) efforts to date have been limited to local areas. The potential reach and acceptability of SLV at the national level is unknown in the United States. To address this gap, we conducted a nationally representative online survey of 1088 parents of school-aged children. We estimate rates of, and factors associated with, future hypothetical parental consent for children to participate in SLV for influenza. Based on logistic regression analysis, we estimate that 51% of parents would be willing to consent to SLV for influenza. Among those who would consent, SLV was reported as more convenient than the regular location (42.1% vs. 19.9%, P<0.001). However the regular location was preferred over SLV for the child's well-being in case of side effects (46.4% vs. 20.9%, P<0.001) and proper administration of the vaccine (31.0% vs. 21.0%, P<0.001). Parents with college degrees and whose child received the 2009-2010 seasonal or 2009 H1N1 influenza vaccination were more likely to consent, as were parents of uninsured children. Several measures of concern about vaccine safety were negatively associated with consent for SLV. Of those not against SLV, schools were preferred as more convenient to the regular location by college graduates, those whose child received the 2009-2010 seasonal or 2009 H1N1 influenza vaccination, and those with greater travel and clinic time. With an estimated one-half of U.S. parents willing to consent to SLV, this study shows the potential to use schools for large-scale influenza vaccination programs in the U.S.

Cost-effectiveness of using 2 vs 3 primary doses of 13-valent pneumococcal conjugate vaccine.

BACKGROUND AND OBJECTIVE: Although effective in preventing pneumococcal disease, 13-valent pneumococcal conjugate vaccine (PCV13) is the most expensive vaccine on the routinely recommended pediatric schedule in the United States. We examined the cost-effectiveness of switching from 4 total doses to 3 total doses by removing the third dose in the primary series in the United States. METHODS: We used a probabilistic model following a single birth cohort of 4.3 million to calculate societal cost savings and increased disease burden from removing the 6-month dose of PCV13. Based on modified estimates of 7-valent pneumococcal conjugate vaccine from randomized trials and observational studies, we assumed that vaccine effectiveness under the 2 schedules is identical for the first 6 months of life and largely similar after administration of the 12- to 15-month booster dose. RESULTS: Removing the third dose of PCV13 would annually save $500 million (in 2011$) but would also result in an estimated 2.5 additional deaths among inpatients with pneumonia or invasive pneumococcal disease. Such dose removal would also result in 261,000 estimated otitis media and 12,000 estimated pneumonia cases annually. These additional illnesses could be prevented through modest increases in coverage. Overall, societal savings per additional life-year lost would be ∼$6 million. When nonfatal outcomes are also considered, savings would range from $143,000 to $4 million per additional quality adjusted life-year lost, depending on the assumptions used for otitis media. CONCLUSIONS: Sizable societal cost savings and a moderate pneumococcal disease increase could be expected from removing the PCV13 primary series' third dose.

Pregnancy dose Tdap and postpartum cocooning to prevent infant pertussis: a decision analysis.

BACKGROUND: Infants <2 months of age are at highest risk of pertussis morbidity and mortality. Until recently, the US Advisory Committee on Immunization Practices (ACIP) recommended protecting young infants by "cocooning" or vaccination of postpartum mothers and other close contacts with tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis, adsorbed (Tdap) booster vaccine. ACIP recommends pregnancy vaccination as a preferred and safe alternative to postpartum vaccination. The ACIP cocooning recommendation has not changed. METHODS: We used a cohort model reflecting US 2009 births and the diphtheria-tetanus-acellular pertussis schedule to simulate a decision and cost-effectiveness analysis of Tdap vaccination during pregnancy compared with postpartum vaccination with or without vaccination of other close contacts (ie, cocooning). We analyzed infant pertussis cases, hospitalizations, and deaths, as well as direct disease, indirect, and public health costs for infants in the first year of life. All costs were updated to 2011 US dollars. RESULTS: Pregnancy vaccination could reduce annual infant pertussis incidence by more than postpartum vaccination, reducing cases by 33% versus 20%, hospitalizations by 38% versus 19%, and deaths by 49% versus 16%. Additional cocooning doses in a father and 1 grandparent could avert an additional 16% of cases but at higher cost. The cost per quality-adjusted life-year saved for pregnancy vaccination was substantially less than postpartum vaccination ($414 523 vs $1 172 825). CONCLUSIONS: Tdap vaccination during pregnancy could avert more infant cases and deaths at lower cost than postpartum vaccination, even when postpartum vaccination is combined with additional cocooning doses. Pregnancy dose vaccination is the preferred alternative to postpartum vaccination for preventing infant pertussis.

Using a discrete choice experiment to elicit time trade-off and willingness-to-pay amounts for influenza health-related quality of life at different ages.

BACKGROUND: Recent research suggests that values for health-related quality of life may vary with the age of the patient. Traditional health state valuation questions and discrete choice experiments are two approaches that could be used to value health. OBJECTIVE: To measure whether public values for health vary with the age of the affected individual. METHODS: A discrete choice experiment was administered via the Internet in December 2007 to measure preferences for different attributes of influenza-related health-related quality of life: age of hypothetical affected individual (range 1-85 years), length of episode (days of illness), severity of illness (workdays lost) and time trade-off or willingness-to-pay amounts. Each respondent answered identical choice questions for a hypothetical family member and for himself/herself. Data on sociodemographic characteristics and influenza illness experience were also collected. Respondents were US adults randomly sampled from an Internet survey panel (n = 1,012). The relative value of attributes was estimated using generalized estimating equations and controlling for sociodemographic characteristics and illness experience. Marginal time traded and marginal willingness to pay using discrete choice and traditional time trade-off or willingness-to-pay questions were compared. RESULTS: Respondents preferred shorter influenza episodes but did not significantly prefer fewer workdays lost if episode length was held constant. Respondents were more likely to choose to avert uncomplicated illness in children and less likely to choose to avert uncomplicated illness in working-age adults. Marginal time trade-off and willingness-to-pay amounts elicited using discrete choice questions were larger than those elicited using direct valuation questions. CONCLUSIONS: Approaches that assume values for health-related quality of life do not vary with the age of a patient may bias economic analyses that use these values. If patient age could affect valuations, then age should be included in the valuation exercise. Additional research should evaluate the effect of patient age on values for other conditions.

Costs of school-located influenza vaccination clinics in Maine during the 2009-2010 H1N1 pandemic.

This study retrospectively estimated costs for a convenience sample of school-located vaccination (SLV) clinics conducted in Maine during the 2009-2010 influenza season. Surveys were developed to capture the cost of labor including unpaid volunteers as well as supplies and materials used in SLV clinics. Six nurses from different school districts completed a clinic day survey on staff time; four of the six also provided data for materials and supplies. For all clinics, average per-dose labor cost was estimated at $5.95. Average per-dose material cost, excluding vaccine, was $5.76. From the four complete clinic survey responses, total per-dose cost was estimated to be an average of $13.51 (range = $4.91-$32.39). Use of donated materials and uncompensated volunteer staff could substantially reduce per-dose cost. Average per-dose cost could also be lowered by increasing the number of doses administered in a clinic.

Coordination costs for school-located influenza vaccination clinics, Maine, 2009 H1N1 pandemic.

School nurses played a key role in Maine's school-located influenza vaccination (SLV) clinics during the 2009-2010 pandemic season. The objective of this study was to determine, from the school district perspective, the labor hours and costs associated with outside-clinic coordination activities (OCA). The authors defined OCA as labor hours spent by staff outside of clinic operations. The authors surveyed a convenience sample of 10 school nurses from nine school districts. Eight nurses responded to the survey, representing seven districts, 45 schools and 84 SLV clinics that provided a total of 22,596 vaccine doses (H1N1 and seasonal combined) to children and adolescents. The mean total OCA time per clinic was 69 hours: out of total hours, 22 (36%) were spent outside regular clinic operation time. The authors estimated the mean cost of OCA to be $15.36 per dose. Survey respondents reported that costs would be lower during non-pandemic seasons and as schools become more proficient at planning clinics.

Parental and societal values for the risks and benefits of childhood combination vaccines.

BACKGROUND: New combination vaccines reduce the number of injections needed for immunization. However, possible drawbacks include higher prices, extra doses of vaccine antigens and increased minor adverse events. Our objective was to measure parental and societal values for attributes of childhood combination vaccines. METHODS: We conducted a discrete choice experiment using an online survey of adults administered by Knowledge Networks. Values were measured for attributes of combination vaccines for a hypothetical child aged 6 months: (1) number of injections, (2) extra dose of hepatitis B vaccine, (3) 20% higher chance of fever, (4) community-level immunization coverage of 2-year-olds of 90% or 80%, and (5) cost per visit. Logistic regression with generalized estimating equations was used to analyze the value of different attributes and generate a marginal willingness-to-pay for a change in attribute level. RESULTS: The response rate was 64% (N=558). Most respondents were parents (63%) and most respondents agreed that combination vaccines were safe (77%). Respondents were willing to pay $7.68 to avoid an injection (compared to $9.94 when looking at parents only). However, respondents were willing to pay $41.57 to avoid higher risk of fever after one set of immunizations (10% versus 30%) and $65.42 for higher immunization coverage rates. These results were very similar for parents only. There was no significant preference to avoid an extra dose of hepatitis B vaccine. CONCLUSIONS: Respondents were willing to pay larger amounts to avoid increased risk of minor adverse events and to increase community-level immunization coverage than to avoid injections. These values should be taken into account when determining the risks and benefits of combination vaccines.