Decision-making for vaccination programs requires additional consideration on broader effects. The cost-effectiveness guidelines published by the Professional Society for Health Economics and Outcomes Research (ISPOR) working group recommends considering broader effects such as herd protection. Whilst difficulty to produce robust data for such factors might hinder quicker decisions, they are important features of vaccination programs and some of them were the narratives that dominated over the COVID-19 pandemic. In this systematic literature review, the perspectives taken and inclusion of broader effects were investigated for recent influenza vaccine economic evaluations.

The search strategy based on the terms influenza vaccination and cost-effectiveness was carried out on Embase and PubMed. Considering the publication date of the ISPOR guidelines, articles since 2019 were searched. The review focus was the perspectives taken and inclusion of broader benefits in the analysis. A link between perspective and inclusion of broader effects was tested with a Chi-square test.

The total number of full cost-effectiveness articles screened was 48. Of those, the number of articles performed from both the perspectives was 18 (37.5%), and 13 articles (27.1%) considered the perspective of payer only. For those that had both perspectives considered, the ICER reported from the societal perspective was consistently lower than that from the payer perspective. Thirty-one articles (65%) included any of the broader effects. However, broader effects considered were limited to indirect protection (17 articles, 35.4%) and productivity loss (22 articles, 45.8%). The relation between perspective and inclusion of broader effects was significant (p=0.04).

This review highlights that studies performed using both payer and societal perspectives as recommended by the ISPOR research guidelines are not many, while more favorable outcomes were presented when the societal perspective was adapted. Broader effects included are productivity loss and indirect protection.

For other broader effects specified in the research guidelines, there are not many attempts to include those in economic evaluations.