Long-Term Sequelae
30-day · 90-day · 1-year Outcomes Beyond Discharge
Flu hospitalization is a bridge, not an endpoint. AMI, stroke, HF, functional decline, and mortality continue for a year after — especially in ≥65 and IC populations.
The invisible tail
Cost-effectiveness models frequently stop counting outcomes at discharge. This underestimates the total burden by 40–60% — 1 in 5 hospitalized ≥65y flu patients die within 12 months, and 1 in 4 lose an ADL by month 6.
1yr mortality (≥65 hosp)
22%
all-cause
90-day readmit (IC)
32%
AMI risk 90d post-flu
4.9× baseline
vs matched baseline
6mo ADL loss
24%
≥65y
Sequelae Timeline — Discharge → 1 Year
Cumulative incidence of key outcomes (mortality, readmit, functional decline)
Curves stratified by tier. IC and multi-morbid cohorts show steepest early ascent.
Cardiovascular Sequelae — 1yr post-flu
AMI, stroke, HF, cardiac death
Flu is now recognized as an independent cardiovascular event trigger. Vaccination reduces post-flu AMI 30%.
Readmission Cascade
30d · 90d · 1yr readmit share by tier
IC patients face 32% 90-day readmission. Each readmission adds ~$9,400 to episode cost.