Table 1.
Demographic and medical characteristics of patients with influenza A and B by season
| 2004–2005 Season | 2005–2006 Season | 2006–2007 Season | 2007–2008 Season | All seasons | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Influenza A (n = 153) [n (%)] | Influenza B (n = 14) [n (%)] | Influenza A (n = 21) [n (%)] | Influenza B (n = 30) [n (%)] | Influenza A (n = 95) [n (%)] | Influenza B (n = 7) [n (%)] | Influenza A (n = 632) [n (%)] | Influenza B (n = 233) [n (%)] | Influenza A (n = 901) [n (%)] | Influenza B (n = 284) [n (%)] | |
| Age | ||||||||||
| 6–23 month | 29 (19) | 5 (36) | 3 (14) | 5 (17) | 19 (20) | 0 (0) | 31 (5) | 12 (5) | 82 (9) | 22 (8) |
| 24–59 month | 8 (5) | 1 (7) | 0 (0) | 3 (10) | 38 (40) | 2 (29) | 64 (10) | 21 (9) | 110 (12) | 27 (10) |
| 5–49 years | 29 (19) | 0 (0) | 5 (24) | 13 (43) | 15 (16) | 0 (0) | 415 (66) | 152 (65) | 464 (52) | 165 (58) |
| 50–64 years | 21 (14) | 3 (21) | 11 (52) | 7 (23) | 21 (22) | 5 (71) | 77 (12) | 31 (13) | 130 (14) | 46 (16) |
| 65+ years | 66 (43) | 5 (36) | 2 (10) | 2 (7) | 2 (2) | 0 (0) | 45 (7) | 17 (7) | 115 (13) | 24 (8) |
| Male | 73 (48) | 6 (43) | 7 (38) | 15 (50) | 44 (46) | 4 (57) | 288 (46) | 107 (46) | 413 (46) | 132 (46) |
| High‐risk medical condition* | 110 (72) | 6 (43) | 12 (57) | 17 (57) | 24 (25) | 1 (14) | 87 (14) | 29 (12) | 233 (26) | 53 (19) |
| Fully vaccinated | 103 (67) | 9 (64) | 12 (57) | 13 (43) | 31 (33) | 2 (29) | 178 (28) | 77 (33) | 324 (36) | 101 (36) |
| Partially vaccinated** | 3 (2) | 0 (0) | 1 (5) | 1 (3) | 2 (2) | 0 (0) | 9 (1) | 1 (0) | 15 (2) | 2 (1) |
| Influenza antiviral Rx*** | 10 (7) | 0 (0) | 2 (10) | 2 (7) | 15 (16) | 0 (0) | 171 (27) | 41 (18) | 198 (22) | 43 (15) |
*High‐risk medical condition was defined by two or more encounters in the previous year with ICD‐9‐CM codes corresponding to chronic illnesses conferring elevated risk for influenza complications.
**Children ≤9 years old were classified as fully immunized only if they had received ≥2 doses of influenza vaccine. Children in this age‐group were classified as partially immunized if they had received only 1 of 2 recommended vaccine doses.
***Prescribed influenza antiviral treatment within 14 days after symptom onset.