TABLE 1.

Estimated Influenza-Associated Hospitalization Rates (Per 100 000 Persons) From Selected Studies

Study YearsPopulationAge GroupPersons in Previously Recognized High-Risk GroupPersons Not in Previously Recognized High-Risk Group
1973–19937,15Tennessee0–11 mo1900496 (0–5 mo)
Medicaid1038 (6–11 mo)
1–2 y800186
3–4 y32086
5–14 y9241
1974–19992Vaccine clinic<2 y200–300
1992–199711Health maintenance organizations0–23 mo144–187
2–4 y0–25
5–17 y8–12
1968–197368Health maintenance organization15–44 y56–11023–25
45–64 y392–63513–23
≥65 y399–518
1969–199569National hospital discharge data<65 y20–42
≥65 y125–228
  • Adapted from MMWR Recomm Rep. 2001;50(RR-4):1–44.