Economic evaluations of vaccines against respiratory infections in adults in Southeast Asia: A systematic review.

Respiratory infections significantly impact adult health in Southeast Asia, yet vaccine coverage remains low. This systematic review evaluated the economic evaluations of vaccines targeting respiratory infections in the region. A comprehensive search was conducted across several databases, including MEDLINE/PubMed, EMBASE, NHSEED, CINAHL, EconLit, Web of Science, Scopus, and Cochrane Library, up to April 24, 2024. Nineteen eligible studies were identified, focusing primarily on influenza (8 studies) and COVID-19 vaccines (7 studies), with fewer studies on pneumococcal (2 studies), varicella (1 study), and pertussis (1 study) vaccines. Overall, influenza, COVID-19 (boosters), and pneumococcal vaccines were found to be cost-effective or highly cost-effective compared to no-vaccine or no-booster scenarios. The only study on maternal pertussis vaccination found it not to be cost-effective. The most common parameters considered in sensitivity analyses were vaccine efficacy and discount rates. This review highlights the economic evaluations of influenza, COVID-19, and pneumococcal vaccines in Southeast Asia, providing essential evidence to guide vaccine policy. Future studies should address limitations in model selection, incorporate herd immunity, ensure the model validation (i.e. validity of cost and benefit measurements), and explore the cost-effectiveness of other vaccines across the region.