Cost-effectiveness analysis of switching from a trivalent to a quadrivalent inactivated influenza vaccine in the Peruvian immunisation programme

BackgroundSeasonal influenza is an acute respiratory infection mostly caused by type A and B influenza viruses. The severe form of the infection can be life-threatening and lead to a significant burden. Vaccination is the most efficient way of preventing influenza infections and limit this burden.ObjectivesTo assess the cost-effectiveness of switching from a trivalent influenza vaccine (TIV) to a quadrivalent influenza vaccine (QIV) in the vaccination programme in Peru, and to evaluate the health and economic impact of reaching the vaccination coverage rate targeted by the Ministry of Health.MethodsA decision-analytic static cost-effectiveness model, was adapted to the Peruvian setting under both payer and societal perspectives.ResultsA switch from TIV to QIV would prevent 29,126 additional cases (including 12,815 consultations), 54 hospitalisations, and 23 deaths related to influenza, mostly in the population <2 years-old and >60 years-old. This would lead to a saving of US $505,206 under the payer perspective, that would partially offset the investment necessary to introduce QIV into the immunisation programme. The resulting incremental cost-effectiveness ratio (ICER) is $16,649 per QALYs gained. The main drivers of the model results were vaccine efficacy against influenza B viruses, degree of match, vaccines prices and proportion of cases attributable to influenza B. The robustness of the results seems satisfactory as QIV has the probability of being a cost-effective strategy of 83.8% (considering a threshold of three GDP per capita). Reaching the coverage targeted by the Ministry of Health would result in health benefits and disease management savings, and lower ICERs.ConclusionIntroducing QIV instead of TIV in the Peruvian immunisation programme is expected to be a cost-effective strategy, especially in younger children and the elderly. The benefit of QIV would be even more important if the coverage targeted by the Ministry of Health would be reached in the most vulnerable groups.     

Cost-effectiveness of dual influenza and pneumococcal vaccination among the elderly in Shenzhen,China

ObjectiveTo assess the cost-effectiveness of dual influenza and pneumococcal vaccination for the elderly in Shenzhen, China.MethodsA Markov state-transition model with a weekly cycle was developed to compare the outcomes of dual influenza and pneumococcal vaccination for the prevention of influenza and pneumococcal infections compared with no vaccination among 70–74 years old people in Shenzhen over 5 years. The model allowed seasonal variation of influenza activity. We calculated the incremental cost-effectiveness ratio (ICER) with costs and quality-adjusted life years (QALYs) discounted at 5% annually from the societal perspective. The impact of parameter uncertainty on the results was examined using one-way and probabilistic sensitivity analyses (PSA).ResultsIn the base case, dual vaccination prevented 5042 influenza infections, 26 IPD cases, 3 disabilities, 34 deaths, and cost US$7.1 per person while resulting in a net gain of 0.0026 QALYs compared with no vaccination. Using once the Chinese gross domestic product per capita in 2019 (US$10,289) as the willingness-to-pay threshold, dual vaccination was cost-effective with an ICER of US$2699 per QALY gained. One-way sensitivity analyses showed that the ICER was relatively sensitive to changes in influenza attack rates and influenza vaccine effectiveness. Based on the results of PSA with 1000 Monte Carlo simulations, receiving both vaccines was cost-effective in 100% of the repetitions.ConclusionThe current study provides evidence that dual influenza and pneumococcal vaccination is a cost-effective disease prevention strategy for the elderly in Shenzhen, China.     

Cost-effectiveness of an influenza vaccination program offering intramuscular and intradermal vaccines versus intramuscular vaccine alone for elderly

BackgroundIntradermal (ID) injection is an alternative route for influenza vaccine administration in elderly with potential improvement of vaccine coverage. This study aimed to investigate the cost-effectiveness of an influenza vaccination program offering ID vaccine to elderly who had declined intramuscular (IM) vaccine from the perspective of Hong Kong public healthcare provider.MethodsA decision analytic model was used to simulate outcomes of two programs: IM vaccine alone (IM program), and IM or ID vaccine (IM/ID program) in a hypothetic cohort of elderly aged 65 years. Outcome measures included influenza-related direct medical cost, infection rate, mortality rate, quality-adjusted life years (QALYs) loss, and incremental cost per QALY saved (ICER). Model inputs were derived from literature. Sensitivity analyses evaluated the impact of uncertainty of model variables.ResultsIn base-case analysis, the IM/ID program was more costly (USD52.82 versus USD47.59 per individual to whom vaccine was offered) with lower influenza infection rate (8.71% versus 9.65%), mortality rate (0.021% versus 0.024%) and QALYs loss (0.00336 versus 0.00372) than the IM program. ICER of IM/ID program was USD14,528 per QALY saved. One-way sensitivity analysis found ICER of IM/ID program to exceed willingness-to-pay threshold (USD39,933) when probability of influenza infection in unvaccinated elderly decreased from 10.6% to 5.4%. In 10,000 Monte Carlo simulations of elderly populations of Hong Kong, the IM/ID program was the preferred option in 94.7% of time.ConclusionsAn influenza vaccination program offering ID vaccine to elderly who had declined IM vaccine appears to be a highly cost-effective option.     

Cost-effectiveness analysis of influenza vaccination during pregnancy in Japan

BackgroundPregnant women and infants are known as high risk groups for influenza. WHO recommend pregnant women be vaccinated with inactivated influenza vaccine. In Japan, some municipalities started to give subsidy to encourage pregnant women to receive a shot on their own accord, which has made the introduction of seasonal antepartum maternal vaccination program (AMVP) into the routine vaccination list a current topic in health policy and has raised the need to evaluate the value for money of such possibility.MethodsWe conducted a cost-effectiveness analysis to evaluate the efficiency of conducting AMVP in Japan. A decision tree model was adopted taking into consideration the duration of single-year vaccine effectiveness for infants and for mothers. The program targeted pregnant women aged 20–49 years old at or over 12 weeks gestation during October 1 through March 30. Estimated probabilities of treatments received due to influenza for pregnant/postpartum women or their infants varied by calendar time, vaccination status, and/or gestational age. Incremental cost-effectiveness ratio (ICER) compared with current no-AMVP from societal perspective was calculated. Transition probabilities, utility weights to estimate quality-adjusted life year (QALY), and disease treatment costs were either calculated or extracted from literature. Costs per vaccination was assumed at ¥3,529/US$32.1.ResultsAMVP reduces disease treatment costs, while the reduction cannot offset the vaccination cost. Incremental QALYs were at 0.00009, among them 84.2% were from infants. ICER was ¥7,779,356/US$70,721 per QALY gained. One-way sensitivity analyses revealed that vaccine effectiveness for infant and costs per shot were the two main key variables affecting the ICER.ConclusionWe found that vaccinating pregnant women with influenza vaccine to prevent unvaccinated infants and pregnant/postpartum women from influenza-associated disease in Japan can be cost-effective from societal perspective, under the WHO-suggested “cost-effective” criteria (1–3 times of GDP).     

Cost-Effectiveness Analysis of a Television Campaign to Promote Seasonal Influenza Vaccination Among the Elderly

BackgroundThe U.S. policy goals regarding influenza vaccination coverage rate among the elderly include the increase in the coverage rate and the elimination of disparities across racial/ethnic groups.ObjectiveTo examine the potential effectiveness of a television (TV) campaign to increase seasonal influenza vaccination among the elderly.MethodsWe estimated the incremental cost-effectiveness ratio (ICER, defined as incremental cost per additionally vaccinated Medicare individual) of a hypothetical nationwide TV campaign for influenza vaccination compared with no campaign. We measured the effectiveness of the nationwide TV campaign (advertised once a week at prime time for 30 seconds) during a 17-week influenza vaccination season among four racial/ethnic elderly groups (N=39 million): non-Hispanic white (W), non-Hispanic African American (AA), English-speaking Hispanic (EH), and Spanish-speaking Hispanic (SH).ResultsThe hypothetical campaign cost was $5,960,000 (in 2012 US dollars). The estimated campaign effectiveness ranged from −1.1% (the SH group) to 1.42% (the W group), leading to an increased disparity in influenza vaccination among non-Hispanic white and non-Hispanic African American (W-AA) groups (0.6 percentage points), W-EH groups (0.1 percentage points), and W-SH groups (1.5 percentage points). The estimated ICER was $23.54 (95% confidence interval $14.21–$39.37) per additionally vaccinated Medicare elderly in a probabilistic analysis. Race/ethnicity-specific ICERs were lowest among the EH group ($22.27), followed by the W group ($22.47) and the AA group ($30.55). The nationwide TV campaign was concluded to be reasonably cost-effective compared with a benchmark intervention (with ICER $44.39 per vaccinated individual) of a school-located vaccination program. Break-even analyses estimated the maximum acceptable campaign cost to be $14,870,000, which was comparable to the benchmark ICER.ConclusionsThe results could justify public expenditures on the implementation of a future nationwide TV campaign, which should include multilingual campaigns, for promoting seasonal influenza vaccination.     

Cost-effectiveness of quadrivalent versus trivalent influenza vaccine for elderly population in China

BackgroundInfluenza-associated excess death occurred most in the elderly. We aimed to assess the cost-effectiveness of quadrivalent influenza vaccine (QIV) versus trivalent influenza vaccine (TIV) for prevention of influenza infection among elderly population in China.MethodsA decision-analytic model was developed to compare 1-year clinical and economic outcomes of three influenza vaccination options (no vaccination, TIV, and QIV) in a hypothetical cohort of Chinese elderly aged 69 years. Outcome measures included cost, influenza infection rate, influenza-related mortality rate, quality-adjusted life-years (QALY) loss, and incremental cost-effectiveness ratio (ICER) from societal perspective. Sensitivity analyses were performed to examine the uncertainty of model inputs.ResultsBase-case results showed no vaccination was dominated (more costly at higher QALY loss) by TIV and QIV. QIV was more costly (USD56.29 versus USD54.28) with lower influenza infection rate (0.608 versus 0.623), mortality rate (0.00199 versus 0.00204), and QALY loss (0.01213 versus 0.01243) than TIV. QIV was cost-effective compared to TIV with ICER of 6,700 USD/QALY below the willingness-to-pay threshold (29,580 USD/QALY). One-way sensitivity analysis found the cost-effectiveness of QIV was subject to the relative risk of vaccine effectiveness of QIV versus TIV, and TIV would be cost-effective if the relative risk was below 1.05. In 10,000 Monte Carlo simulations, the probabilities of QIV, TIV, and no vaccination to be cost-effective were 86.3%, 13.7%, and 0%, respectively.ConclusionQIV appears to be a cost-effective option compared to TIV and no influenza vaccination for elderly population in China.     

Effectiveness of influenza vaccination for children in Japan: Four-year observational study using a large-scale claims database

BackgroundTo date, few large-scale comparative effectiveness studies of influenza vaccination have been conducted in Japan, since marketing authorization for influenza vaccines in Japan has been granted based only on the results of seroconversion and safety in small-sized populations in clinical trial phases not on the vaccine effectiveness. We evaluated the clinical effectiveness of influenza vaccination for children aged 1–15 years in Japan throughout four influenza seasons from 2010 to 2014 in the real world setting.MethodsWe conducted a cohort study using a large-scale claims database for employee health care insurance plans covering more than 3 million people, including enrollees and their dependents. Vaccination status was identified using plan records for the influenza vaccination subsidies.The effectiveness of influenza vaccination in preventing influenza and its complications was evaluated. To control confounding related to influenza vaccination, odds ratios (OR) were calculated by applying a doubly robust method using the propensity score for vaccination.ResultsTotal study population throughout the four consecutive influenza seasons was over 116,000. Vaccination rate was higher in younger children and in the recent influenza seasons. Throughout the four seasons, the estimated ORs for influenza onset were statistically significant and ranged from 0.797 to 0.894 after doubly robust adjustment. On age stratification, significant ORs were observed in younger children. Additionally, ORs for influenza complication outcomes, such as pneumonia, hospitalization with influenza and respiratory tract diseases, were significantly reduced, except for hospitalization with influenza in the 2010/2011 and 2012/2013 seasons.ConclusionsWe confirmed the clinical effectiveness of influenza vaccination in children aged 1–15 years from the 2010/2011 to 2013/2014 influenza seasons. Influenza vaccine significantly prevented the onset of influenza and was effective in reducing its secondary complications.     

Cost-effectiveness analysis of quadrivalent seasonal influenza vaccines in Beijing: A modeling analysis

BackgroundSince 2007, Beijing has offered a free trivalent influenza vaccine (TIV) for residents aged ≥ 60 years and school students. The quadrivalent influenza vaccine (QIV) was administered to school children in 2018 and will be administered to elderly adults in the future. In addition, health care workers (HCWs) who are involved in the prevention and control of COVID-19 were included in the program in 2020. This study aimed to analyze the cost-effectiveness of a comprehensive list of combined strategies of TIV and QIV for school children, elderly adults, and HCWs to identify the most cost-effective strategy.MethodsA decision tree was developed to compare 1-year outcomes of TIV vs. QIV in three risk groups: school children, elderly adults, and HCWs. The outcome was incremental cost per quality-adjusted life-year (QALY). Probabilistic sensitivity analyses and scenario analyses were developed to assess the robustness of the results.ResultsFrom the perspective of society, this study found that the introduction of QIVs can be cost-effective for any and all targeted groups with a willingness-to-pay threshold of 3-fold GDP per capita. Among all programs, program H (all school children, elderly adults, and HCWs received the QIV) showed a 79% probability of being cost-effective with an incremental cost-effectiveness ratio (ICER) of 13,580 (95% CI: 13,294, 13,867) US$/QALY and was the preferred option in the base case scenario.ConclusionThe introduction of QIVs to school children, elderly adults, or HCWs is likely to be cost-effective, either separately or collectively. The introduction of QIV to school children, elderly adults, and health care workers simultaneously showed the highest probability of being cost-effective and was the preferred option.     

Cost-effectiveness analyses of 15- and 20-valent pneumococcal conjugate vaccines for Japanese elderly

BackgroundDespite the 23-valent pneumococcal polysaccharide vaccine (PPSV23) vaccination programme implementation, pneumococcal disease (PD) remains an important cause of morbidity and mortality among the elderly in Japan, particularly since childhood pneumococcal conjugate vaccine (PCV) vaccination programme continues to alter the serotype PD distribution among the elderly. Recently, in the United States, PCV15/PCV20 were recommended for adults aged ≥ 65 years and those aged 19–64 years with certain underlying conditions. In Japan, PCV15 is under the approval application process and PCV20 undergoing clinical trials, which has warranted the need in evaluating their value for money.MethodsWe conducted cost-effectiveness analyses with Markov model and calculated incremental cost-effectiveness ratios of PCV15/PCV20 vaccination programme compared to status quo from payers’ perspective. Transition probabilities and utility weights in estimating quality-adjusted life-year (QALY), and disease treatment costs were either estimated or obtained from literature. To reflect the situation of COVID-19 pandemic, epidemiological data from 2020 and beyond were used.ResultsCompared to the current vaccination programme, PCV20 vaccination programme gained more QALYs with less cost, while PCV15 vaccination programme cost ¥35,020 (US$318, US$1 = ¥110) to gain an additional QALY. Replacing PPSV23 vaccination programme with PCV20 vaccination programme is cost-saving. One-way sensitivity analyses revealed that lower VE limits of PCVs against non-bacteremic pneumonia (NBP) have large impact to change the result from PCV20 vaccination programme dominated PPSV23 vaccination programme to PPSV23 vaccination programme dominated PCV20 vaccination programme.ConclusionIn the COVID-19 era, replacing current PPSV23 with a single-dose PCV15- or PCV20 immunisation programme for 65-year-old adults in Japan is highly cost-effective, while the PCV 20 vaccination programme was observed to be more favourable.     

Cost-effectiveness of pertussis booster vaccination for preschool children in Japan

Introduction: Japan currently recommends four doses of the diphtheria-tetanus-acellular pertussis (DTaP) vaccine in its routine vaccination program, but the introduction of a fifth dose is currently under consideration. An objective of the booster vaccination is to prevent severe cases of pertussis in infants through herd immunity. Thus, the aim of this analysis was to demonstrate the cost-effectiveness of a fifth-dose of the DTaP vaccine for 6-year-old children, taking herd immunity for unvaccinated infants into account.MethodAn economic model analysis was conducted comparing the cost and effectiveness of the two strategies based on quality-adjusted life years (QALYs). We evaluated the incremental cost-effectiveness ratio (ICER) of the booster strategy to the no booster strategy. This model contained two sub-models: one for children aged 6 years or older and one for infants under 3 months old. Herd immunity for infants is modeled as when siblings in the same family are infected.ResultsThe ICER was JPY 71,605,491 (USD 656,931) per QALY gained from the societal perspective, and 7.10% of incremental QALYs (0.0000934) were from a reduction in infant infection. In the sensitivity analysis, no variables moved the ICER under the threshold (JPY 5,000,000 per QALY gained), and the duration of pertussis disease and the incidence rate of pertussis had a significant impact on the ICER. When the disease burden of pertussis decreased, the booster strategy resulted in fewer QALYs gained and greater costs compared with the no booster strategy.ConclusionThe introduction of a DTaP booster vaccination to the routine immunization schedule can be expected to reduce the number of pertussis cases in the target population. However, our study showed that adding a booster vaccination for 6-year-old children to the schedule in Japan would not be cost-effective in terms of achieving herd immunity among unvaccinated infants.     

Acceptance and feasibility of school-based seasonal influenza vaccination in Singapore: A qualitative study

IntroductionInfluenza is a major cause of disease in children. School-based seasonal influenza vaccination can be a cost-effective tool to improve vaccine uptake among children, and can bring substantial health and economic benefits to the broader community. The acceptance and feasibility of school-based influenza vaccination are likely to be highly context-specific, but limited data exist from tropical settings with year-round influenza transmission. We conducted a qualitative study to assess acceptability and feasibility of a school-based seasonal influenza vaccination programme in Singapore.MethodsWe conducted qualitative in-depth interviews with key stakeholders, including healthcare professionals, representatives of relevant ministries, preschool principals and parents to understand their perspectives on a proposed school-based seasonal influenza vaccination programme. Interviews were transcribed verbatim and analysed using thematic analysis.ResultsWe conducted 40 interviews. Although preschool-aged children are currently the recommended age group for vaccination, stakeholders suggested introducing the programme in primary and/or secondary schools, where existing vaccination infrastructure would facilitate delivery. However, more comprehensive evidence on the local influenza burden and transmission patterns among children is required to develop an evidence-based, locally relevant rationale for a school-based vaccination programme and effectively engage policy-makers, school staff, and parents. Extensive, age-appropriate public education and awareness campaigns would increase the acceptability of the programme among stakeholders. Stakeholders indicated that an opt-out programme with free or subsidised vaccination would be the most likely to achieve high vaccine coverage and make access to vaccination more equitable.ConclusionsOverall, participants were supportive of a free or subsidised school-based influenza vaccination programme in primary and/or secondary schools, although children in this age group are not currently a recommended group for vaccination. However, a better informed, evidence-based rationale to estimate the programme’s impact in Singapore is currently lacking. Extensive, age-appropriate public education and awareness campaigns will help ensure full support across key stakeholder groups.     

Cost-effectiveness of 13-valent pneumococcal conjugate vaccination in Mongolia

ObjectiveThe Ministry of Health (MOH), Mongolia, is considering introducing 13-valent pneumococcal conjugate vaccine (PCV13) in its national immunization programme to prevent the burden of disease caused by Streptococcus pneumoniae. This study evaluates the cost-effectiveness and budget impact of introducing PCV13 compared to no PCV vaccination in Mongolia.MethodsThe incremental cost-effectiveness ratio (ICER) of introducing PCV13 compared to no PCV vaccination was assessed using an age-stratified static multiple cohort model. The risk of various clinical presentations of pneumococcal disease (meningitis, pneumonia, non-meningitis non-pneumonia invasive pneumococcal disease and acute otitis media) at all ages for thirty birth cohorts was assessed. The analysis considered both health system and societal perspectives. A 3 + 0 vaccine schedule and price of US$3.30 per dose was assumed for the baseline scenario based on Gavi, the Vaccine Alliance’s advance market commitment tail price.ResultsThe ICER of PCV13 introduction is estimated at US$52 per disability-adjusted life year (DALY) averted (health system perspective), and cost-saving (societal perspective). Although indirect effects of PCV have been well-documented, a conservative scenario that does not consider indirect effects estimated PCV13 introduction to cost US$79 per DALY averted (health system perspective), and US$19 per DALY averted (societal perspective). Vaccination with PCV13 is expected to cost around US$920,000 in 2016, and thereafter US$820,000 every year. The programme is likely to reduce direct disease-related costs to MOH by US$440,000 in the first year, increasing to US$510,000 by 2025.ConclusionIntroducing PCV13 as part of Mongolia’s national programme appears to be highly cost-effective when compared to no vaccination and cost-saving from a societal perspective at vaccine purchase prices offered through Gavi. Notwithstanding uncertainties around some parameters, cost-effectiveness of PCV introduction for Mongolia remains robust over a range of conservative scenarios. Availability of high-quality national data would improve future economic analyses for vaccine introduction.     

Safety and immunogenicity of a seasonal quadrivalent influenza vaccine (GC3110A) in healthy participants aged ≥ 65 years

BackgroundSeasonal Influenza is still considered associated with seasonal morbidity and hospitalization in the elderly population. The World Health Organization (WHO) recommended seasonal quadrivalent influenza vaccine (QIV) to reduce burden of two currently circulating influenza B lineages. Until 2019 Korean National Immunization Program (NIP) recommended trivalent influenza vaccine (TIV) after ongoing debates on cost effectiveness of QIV for elderly population. Although influenza vaccine only showed modest effect on reducing influenza in elderly, this study aimed to evaluate the immunogenicity and safety of inactivated QIV in healthy participants ≥ 65 years of age.MethodsA total of 274 healthy participants aged ≥ 65 years received a QIV. Seroconversion-based vaccine efficacy of 4 strains of seasonal influenza was assessed 21 days after vaccination and adverse events were monitored until 180 days after vaccination.ResultsThe percentages of participants seroconverted after vaccination on HI antibody against each strain were 36.5% (99/271) to A/H1N1, 47.6% (129/271) to A/H3N2, 40.6% (110/271) to B Yamagata, and 49.1% (133/271) to B Victoria. The percentages of participants seroprotected after vaccination on HI antibody against each strain were 81.2% (220/271) to A/H1N1, 98.5% (267/271) to A/H3N2, 95.2% (258/271) to B Yamagata, and 93.7% (254/271) to B Victoria. There was no serious adverse event (SAE) related with the study vaccine.ConclusionThe quadrivalent split influenza vaccine is expected to offer seroprotection against influenza A and both influenza B lineages even in the elderly population.     

Influenza vaccine effectiveness in preventing hospitalization among Beijing residents in China, 2013–15

BackgroundEstimates of influenza vaccination effectiveness (VE) are valuable for populations where the vaccine has been promoted in order to support vaccination policy and to permit evaluation of vaccination strategies. Such studies would be important for China due to limited data available during seasons when the vaccine strains matched or mismatched the circulating viruses.MethodsWe conducted a test-negative study in hospitals in Beijing. Patients admitted to five hospitals in the city were enrolled during the winter influenza seasons of 2013–14 and 2014–15. Influenza virus infections were determined by PCR, and influenza vaccination records were extracted from a centralized electronic immunization registry. Influenza VE was estimated by logistic regression adjusting for age group, sex and chronic conditions, and matched by calendar week.ResultsA total of 2368 inpatients were recruited during the study period with a vaccination coverage in the control group of 12.8%. The overall estimate of influenza VE was 46.9% (95% CI: −20.4%, 76.6%) for the 2013–14 season and 5.0% (95% CI: −53.0%, 41.0%) for the 2014–15 season. Estimates of VE were relatively higher in children aged 6–17 years than older persons across two influenza seasons while estimates of VE for both adults and elderly were relatively low.ConclusionsOur findings were consistent with expected influenza vaccination effectiveness in seasons when the vaccine matched or mismatched circulating viruses. Strategies to increase influenza vaccine coverage could provide a public health benefit.     

Inactivated influenza vaccine effectiveness and an analysis of repeated vaccination for children during the 2016/17 season

ObjectivesWe assessed the vaccine effectiveness (VE) of inactivated influenza vaccine (IIV) in children 6 months to 15 years of age during the 2016/17 season. In addition, we estimated the impact of repeated vaccination in children on VE.MethodsOur study for VEs in preventing influenza and admission due to influenza were conducted according to a test-negative case-control design (TNCC) based on influenza rapid diagnostic test results. We also analyzed the VE by vaccine status in the current and previous seasons for the impact of repeated vaccination.ResultsDuring the 2016/17 season, the quadrivalent IIV was used in Japan. The adjusted VE in preventing influenza illness was 38% (95% CI, 29–46) against influenza A and 39% (95% CI, 18–54) against influenza B. Infants showed no significant VE. The VE in preventing hospitalization was not demonstrated. For the analysis of repeated vaccination, the vaccine was effective only when immunization occurred in the current season. The children who were immunized in two consecutive seasons were more likely to develop influenza compared to those immunized in the current season only (odds ratio, 1.58 [95% CI, 1.05–2.38], adjusted odds ratio, 1.53 [95% CI, 0.99–2.35]). However, the odds ratio of repeated vaccination was not significant when the analysis excluded those who developed influenza in the previous season.ConclusionsVE in children in the 2016/17 season was similar to values previously reported. Repeated vaccination interfered with the VE against any influenza infection in the 2016/17 season. The results of our study suggest that decreased VE by repeat vaccination phenomenon was associated with immunity by influenza infection in the previous season. However, the influenza vaccine should be recommended every season for children.     

Factors associated with parental acceptance of seasonal influenza vaccination for their children – A telephone survey in the adult population in Germany

IntroductionInfluenza vaccination of children with underlying chronic diseases is currently recommended in Germany, but targeting all children constitutes an alternative approach to control seasonal influenza. To inform the modelling of vaccination impact and possible communication activities, we aimed to assess among parents the acceptance of universal childhood vaccination against seasonal influenza and possible modifiers.MethodsWe conducted a telephone survey in households in Germany using random digit dialing. We interviewed parents with children aged <18 years by constructing three hypothetical scenarios in subsequent order: (1) hearing about the influenza vaccination recommendation through the media, (2) the vaccine being recommended by a physician, and (3) being informed about the availability of the vaccine as a nasal spray. We calculated the proportion of parents who would immunize their child and used univariable and multivariable logistic regression to identify factors associated with influenza vaccination intention.ResultsResponse was between 22 and 46%. Of 518 participants, 74% were female, mean age was 41.3 years. Participants had on average 1.6 children with a mean age of 8.9 years. In scenario 1, 52% of parents would immunize their child, compared to 64% in scenario 2 (p < 0.01) and to 45% in scenario 3 (p = 0.20). Factors independently associated with vaccination acceptance in scenario 1 were previous influenza vaccination of the child or parent (adjusted odds ratio [aOR] 4.5 and 8.6, respectively), perceived severity of influenza (aOR = 5.1) and living in eastern Germany (aOR = 2.4).ConclusionIf seasonal influenza vaccination was recommended for all children, more than half of the parents would potentially agree to immunize their child. Involving physicians in future information campaigns is essential to achieve high uptake. As intranasal vaccine administration is non-invasive and easily done, it remains unclear why scenario 3 was associated with low acceptance among parents, and the underlying reasons should be further explored.     

A cost-effectiveness analysis of South Africa’s seasonal influenza vaccination programme

BackgroundSeasonal influenza imposes a significant health and economic burden in South Africa, particularly in populations vulnerable to severe consequences of influenza. This study assesses the cost-effectiveness of South Africa’s seasonal influenza vaccination strategy, which involves vaccinating vulnerable populations with trivalent inactivated influenza vaccine (TIV) during routine facility visits. Vulnerable populations included in our analysis are persons aged ≥ 65 years; pregnant women; persons living with HIV/AIDS (PLWHA), persons of any age with underlying medical conditions (UMC) and children aged 6–59 months.MethodWe employed the World Health Organisation’s (WHO) Cost Effectiveness Tool for Seasonal Influenza Vaccination (CETSIV), a decision tree model, to evaluate the 2018 seasonal influenza vaccination campaign from a public healthcare provider and societal perspective. CETSIV was populated with existing country-specific demographic, epidemiologic and coverage data to estimate incremental cost-effectiveness ratios (ICERs) by comparing costs and benefits of the influenza vaccination programme to no vaccination.ResultsThe highest number of clinical events (influenza cases, outpatient visits, hospitalisation and deaths) were averted in PLWHA and persons with other UMCs. Using a cost-effectiveness threshold of US$ 3 400 per quality-adjusted life year (QALY), our findings suggest that the vaccination programme is cost-effective for all vulnerable populations except for children aged 6–59 months. ICERs ranged from ~US$ 1 750 /QALY in PLWHA to ~US$ 7 500/QALY in children. In probabilistic sensitivity analyses, the vaccination programme was cost-effective in pregnant women, PLWHA, persons with UMCs and persons aged ≥65 years in >80% of simulations. These findings were robust to changes in many model inputs but were most sensitive to uncertainty in estimates of influenza-associated illness burden.ConclusionSouth Africa's seasonal influenza vaccination strategy of opportunistically targeting vulnerable populations during routine visits is cost-effective. A budget impact analysis will be useful for supporting future expansions of the programme.     

Estimated influenza illnesses and hospitalizations averted by influenza vaccination among children aged 6–59 months in Suzhou,China, 2011/12 to 2015/16 influenza seasons

BackgroundThere are few estimates of vaccination-averted influenza-associated illnesses in China.MethodsWe used a mathematical model and Monte Carlo algorithm to estimate numbers and 95% confidence intervals (CI) of influenza-associated outcomes (hospitalization, illness, and medically-attended (MA) illness) averted by vaccination among children aged 6–59 months in Suzhou from October 2011–September 2016. Influenza illnesses included non-hospitalized MA influenza illnesses and non-MA influenza illnesses. The numbers of influenza-associated outcomes averted by vaccination were the difference between the expected burden if there were no vaccination given and the observed burden with vaccination. The model incorporated the disease burden estimated based on surveillance data from Suzhou University Affiliated Children’s Hospital (SCH) and data from health utilization surveys conducted in the catchment area of SCH, age-specific estimates of influenza vaccination coverage in Suzhou from the Expanded Program on Immunization database, and influenza vaccine effectiveness estimates from previous publications. Averted influenza estimations were presented as absolute numbers and in terms of the prevented fraction (PF). A hypothetical scenario with 50% coverage (but identical vaccine effectiveness) over the study period was also modeled.ResultsIn ~250,000 children, influenza vaccination prevented an estimated 731 (CI: 549–960) influenza hospitalizations (PF: 6.2% of expected, CI: 5.8–6.6%) and 10,024 (7593–12,937) influenza illnesses (PF: 6.5%, 6.4–6.7%), of which 8342 (6338–10,768) were MA (PF: 6.6%, 6.4–6.7%) from 2011 to 2016. The PFs declined each year along with decreasing influenza vaccination coverage. If 50% of the study population had been vaccinated over time, the estimated numbers of averted cases during the study period would have been 4059 (3120–5762) influenza hospitalizations (PF: 27.2%, 26.4–27.9%) and 56,215 (42,925–78,849) influenza illnesses (PF: 28.5%, 28.3–28.7%), of which 46,596 (35,662–65,234) would be MA (PF: 28.5%, 28.3–28.7%).ConclusionInfluenza vaccination is estimated to have averted influenza-associated illness outcomes even with low coverage in children aged 6–59 months in Suzhou. Increasing influenza vaccination coverage in this population could further reduce illnesses and hospitalizations.     

Effectiveness of repeated influenza vaccination among the elderly population with high annual vaccine uptake rates during the three consecutive A/H3N2 epidemics

BackgroundAnnually, about 80% of the Korean elderly aged ≥65 years receive influenza vaccination. Repeated annual vaccination has been suggested as an important factor of poor influenza vaccine effectiveness (VE), though reported conflicting results.MethodsDuring the consecutive A/H3N2-dominant influenza seasons between 2012 and 2015, we comparatively evaluated the VE (repeated vs. current season only) against laboratory-confirmed influenza, pneumonia and hospitalization in the elderly aged ≥65 years with influenza-like illness (ILI). Clinical and demographic data were collected prospectively, and vaccination status of prior and current seasons was verified using the immunization registry data of Korean Centers for Disease Control and Prevention.ResultsDuring the first A/H3N2-dominant season in 2012–2013, influenza vaccine showed statistically significant effectiveness against influenza A infection only and when vaccinated in the current season only (VE 53%, 95% CI 15–77). In the latter two seasons (2013–2015 years), the adjusted VE for influenza A was indistinguishable between repeated vaccination and vaccination in the current season only.ConclusionDuring consecutive influenza A/H3N2 epidemics, poor influenza vaccine effectiveness may be more pronounced among the elderly population with a high annual vaccine uptake rate.     

Cost-Effectiveness of Pediatric Influenza Vaccination in The Netherlands

ObjectiveThis study evaluates the cost-effectiveness of extending the Dutch influenza vaccination program for elderly and medical high-risk groups to include pediatric influenza vaccination, taking indirect protection into account.MethodsAn age-structured dynamic transmission model was used that was calibrated to influenza-associated GP visits over 4 seasons (2010-2011 to 2013-2014). The clinical and economic impact of different pediatric vaccination strategies were compared over 20 years, varying the targeted age range, the vaccine type for children or elderly and high-risk groups. Outcome measures include averted symptomatic infections and deaths, societal costs and quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios. Costs and QALYs were discounted at 4% and 1.5% annually.ResultsAt an assumed coverage of 50%, adding pediatric vaccination for 2- to 17-year-olds with quadrivalent live-attenuated vaccine to the current vaccination program for elderly and medical high-groups with quadrivalent inactivated vaccine was estimated to avert, on average, 401 820 symptomatic cases and 72 deaths per year. Approximately half of averted symptomatic cases and 99% of averted deaths were prevented in other age groups than 2- to 17-year-olds due to herd immunity. The cumulative discounted 20-year economic impact was 35 068 QALYs gained and €1687 million saved, that is, the intervention was cost-saving. This vaccination strategy had the highest probability of being the most cost-effective strategy considered, dominating pediatric strategies targeting 2- to 6-year-olds or 2- to 12-year-olds or strategies with trivalent inactivated vaccine.ConclusionModeling indicates that introducing pediatric influenza vaccination in The Netherlands is cost-saving, reducing the influenza-related disease burden substantially.