Potential cost-effectiveness of annual influenza immunization for infants and toddlers: experience from Canada

In 2004, expert groups in North America recommended annual influenza immunization for healthy infants and toddlers aged 6-23 months with a goal of reducing high hospitalization rates (HR). We assess cost-effectiveness of this program in Canada.

Analysis was from third-party payer and societal perspectives in preventing hospitalization and other outcomes among 500,000 vaccinated or non-vaccinated infants/toddlers. Base-case assumptions include: 25% attack rate (AR), 1% case hospitalization rate (HR), 0.002% case fatality, vaccine effectiveness (VE) of 66%, CDN dollar 15 per dose for vaccine and administration, half of mothers requiring 2h from work per dose to immunize and two doses required by 100% (first year) or 33% (subsequent years) of infants/toddlers immunized.

After the first year, infant/toddler influenza immunization costs the third-party approximately CDN dollar 9 per day of illness averted, CDN dollar 120 per physician visit averted, CDN dollar 7000 per hospitalization averted, CDN dollar 3 million per death averted and CDN dollar 450,000 per life year gained. Corresponding costs from societal perspective are approximately CDN dollar 3, CDN dollar 45, CDN dollar 2500, CDN dollar 1 million and CDN dollar 170,000. The program becomes cost-saving from the third-party perspective at AR>55%, HR>4%, or cost per dose (for vaccine and its administration) 74%.

In the base case, infant/toddler influenza immunization is not cost-saving but could become more cost-effective in settings of higher attack rate and lower immunization cost. In this context, immunization of children in daycare or other group settings should be preferentially considered. Economic analyses should routinely inform expansions to influenza immunization programs.