- Deferring influenza vaccination until October or later may decrease effects of waning vaccine effectiveness (VE), improve protection in older (>65 years) adults.
- Benefits may be reversed by early season influenza peaks, substantial vaccine uptake declines.
Why this matters
- Balance maximizing VE persistence with avoiding missed opportunities to vaccinate older adult patients.
- Assuming no declines in uptake during an average influenza season (February peak), compressed vaccination vs status quo resulted in overall influenza case incidence of 5.06% vs 5.09%, respectively (difference, 11,423 cases in 49.2M people), 481 fewer hospitalizations, 134 fewer deaths.
- Early influenza peaks: compressed vaccination rarely favored in seasons with early peaks, never favored in all 4 strains, VE scenarios if overall uptake declined >1.6%.
- Average/late illness peaks: always favored if uptake declined by 5.1, or 5.6% points.
- Markov modeling study analyzing tradeoffs between intraseason influenza vaccine waning in older adults (>65 years) receiving status quo (August-May) vs compressed vaccination (October-May).
- Funding: National Institute of General Medical Sciences.
- Degree of waning linked to high-dose vaccines still unknown.
- Potential heterogeneity unaccounted for.
- VE waning for new vaccines unavailable.
- Herd immunity unmeasured.