Cost-effectiveness of inactivated seasonal influenza vaccination in a cohort of Thai children ≤60 months of age

Abstract

BackgroundVaccination is the best measure to prevent influenza. We conducted a cost-effectiveness evaluation of trivalent inactivated seasonal influenza vaccination, compared to no vaccination, in children ≤60 months of age participating in a prospective cohort study in Bangkok, Thailand.MethodsA static decision tree model was constructed to simulate the population of children in the cohort. Proportions of children with laboratory-confirmed influenza were derived from children followed weekly. The societal perspective and one-year analytic horizon were used for each influenza season; the model was repeated for three influenza seasons (2012–2014). Direct and indirect costs associated with influenza illness were collected and summed. Cost of the trivalent inactivated seasonal influenza vaccine (IIV3) including promotion, administration, and supervision cost was added for children who were vaccinated. Quality-adjusted life years (QALY), derived from literature, were used to quantify health outcomes. The incremental cost-effectiveness ratio (ICER) was calculated as the difference in the expected total costs between the vaccinated and unvaccinated groups divided by the difference in QALYs for both groups.ResultsCompared to no vaccination, IIV3 vaccination among children ≤60 months in our cohort was not cost-effective in the introductory year (2012 season; 24,450 USD/QALY gained), highly cost-effective in the 2013 season (554 USD/QALY gained), and cost-effective in the 2014 season (16,200 USD/QALY gained).ConclusionThe cost-effectiveness of IIV3 vaccination among children participating in the cohort study varied by influenza season, with vaccine cost and proportion of high-risk children demonstrating the greatest influence in sensitivity analyses. Vaccinating children against influenza can be economically favorable depending on the maturity of the program, influenza vaccine performance, and target population.

Economic Burden of Influenza in Thailand: A Systematic Review

“…Total costs were not disaggregated in 4 studies (36%). 21,[23][24][25] Discounting of the costs was not performed in 7 studies (64%) but this was acceptable because discounting is not necessary when a study period is short. Nine studies (82%) had no sensitivity analysis of cost estimation; however, this was defensible as their study designs did not have assumptions on cost estimation or different cost scenarios.…”

“…Briefly, most studies had funding by non-profit organizations and employed a survey and/or hospital database for their cost estimation. Those 11 articles evaluated economic burden of influenza in the 3 main population groups: a) children, [23][24][25] b) older adults, 20,21,26 and c) individuals across various age groups/country. 6,14,22,27,28 Types of influenza illness varied across the studies: (i) influenza-like illness (ILI) which is considered a mild spectrum of influenza, (ii) seasonal influenza, (iii) influenza-associated acute respiratory illness or febrile respiratory illness, (iv) influenza-associated pneumonia, (v) avian influenza (H5N1), and (vi) the 2009 (H1N1) influenza pandemic.…”

“…Indirect costs for inpatients were evaluated in 2 studies (Table 1) and they were found to be smaller compared with the direct medical costs for inpatients. 6,26 The total costs for inpatients tended to depend on concurrent conditions and the severity of influenza as seen that children with high-risk incurred higher total costs than healthy children 24 and severe cases had higher costs than mild cases. 25…”

“…RT-PCR, Reverse transcription-polymerase chain reaction; NA, Not available; ARI in Kittikraisak et al24 …”

Influenza virus seroincidence in a cohort of healthy and high-risk children enrolled in infancy, Bangkok, Thailand

“…Enrollment method and study procedures have been previously described (Kittikraisak et al, 2018;Kittikraisak et al, 2017). Briefly, a prospective cohort study (Pediatric Respiratory Infection Cohort Evaluation, the PRICE study) to determine influenza burden among children living in the Bangkok Metropolitan areas who sought care at QSNICH (for any cause except acute respiratory illness) was established in August 2011.…”