OBJECTIVES: In many countries, RSV is a seasonal disease, with a peak in incidence and hospitalizations during the winter, when hospitals operate close to capacity and the marginal cost of each admission is presumably the highest. However, cost-effectiveness analyses of RSV and other seasonal diseases often rely on reference unit costs for hospitalizations based on yearly averages. The broader societal value of reducing healthcare system pressure during the winter is thus often not accounted for. We investigate the impact of explicitly incorporating the excess cost of hospitalizations during these months on the cost-effectiveness of maternal RSV vaccination in Norway.

METHODS: We estimate the incremental cost-effectiveness ratio (ICER) of a national maternal vaccination campaign targeting infants born during the RSV season in Norway. We explore the relative reduction in the ICER when accounting for scarce healthcare resources during peak RSV season, by increasing the cost of hospital admissions during the winter months (December through February) and decreasing them by the same amount during the summer (June through August), while keeping all other assumptions constant.

RESULTS: An average 1 422 infants are hospitalized due to RSV each year in Norway. 72 percent of these hospitalizations occur during winter months. Increasing the cost of hospitalizations during the winter (and decreasing them during the summer) by 10, 25 and 50 percent, reduces the ICER by 33, 83 and 164 percent, respectively. When winter hospitalization costs are 30 percent higher than reference values (and summer hospitalization costs are 30 percent lower), the vaccination campaign becomes the dominant alternative.

CONCLUSIONS: The use of reference costs for hospitalizations may severely underestimate the cost-effectiveness and societal value of preventive healthcare measures such as RSV maternal vaccination campaigns. Further research is needed to understand the within-year variation in hospitalization costs.