Table 1.
Characteristics of Index Case Patients With Influenza A(H3N2) or B Virus Infection and Their Household Contacts
| Characteristics | Influenza A(H3N2) | Influenza B |
|---|---|---|
| Index cases | ||
| No. of index cases | 76 | 39 |
| Age, years | ||
| 0–5 | 47 (62) | 16 (41) |
| 6–17 | 24 (32) | 22 (56) |
| >17 | 5 (7) | 1 (3) |
| Male | 40 (53) | 22 (56) |
| Prior vaccination | 2 (3) | 3 (8) |
| Oseltamivir treatment | 67 (88) | 37 (95) |
| Microbial community type | ||
| 1 | 23 (30) | 8 (21) |
| 2 | 17 (22) | 6 (15) |
| 3 | 10 (13) | 5 (13) |
| 4 | 10 (13) | 8 (21) |
| 5 | 15 (20) | 10 (26) |
| Missing | 1 (1) | 2 (5) |
| Number of household contacts | ||
| 1–3 | 45 (59) | 25 (64) |
| 4–5 | 17 (22) | 6 (15) |
| ≥6 | 14 (18) | 8 (21) |
| Number of secondary cases in household | ||
| 0 | 51 (67) | 18 (46) |
| 1 | 15 (20) | 14 (36) |
| 2 | 5 (7) | 5 (13) |
| ≥3 | 5 (7) | 2 (5) |
| Symptom profile | ||
| Fever | 76 (100) | 39 (100) |
| Rhinorrhea | 74 (97) | 37 (95) |
| Sore throat | 37 (49) | 15 (38) |
| Cough | 72 (95) | 36 (92) |
| ILIa | 72 (95) | 37 (95) |
| Household contacts | ||
| No. of contacts | 286 | 150 |
| Age, years | ||
| 0–5 | 33 (12) | 19 (13) |
| 6–17 | 88 (31) | 45 (30) |
| >17 | 165 (58) | 86 (57) |
| Male | 106 (37) | 58 (39) |
| Prior vaccination | 6 (2) | 18 (12) |
| Bacterial community type | ||
| 1 | 72 (25) | 36 (24) |
| 2 | 57 (20) | 38 (25) |
| 3 | 69 (24) | 30 (20) |
| 4 | 41 (14) | 23 (15) |
| 5 | 36 (13) | 14 (9) |
| Missing | 11 (4) | 9 (6) |
| Household contacts with RT-PCR–confirmed infection | ||
| Overall | 43/286 (15) | 32/150 (21) |
| Age, years | ||
| 0–5 | 13/33 (39) | 8/19 (42) |
| 6–17 | 17/88 (19) | 16/45 (36) |
| >17 | 13/165 (8) | 8/86 (9) |
| Symptom profile | ||
| Fever | 19/43 (44) | 22/32 (69) |
| Rhinorrhea | 24/43 (56) | 20/32 (62) |
| Sore throat | 15/43 (35) | 14/32 (44) |
| Cough | 26/43 (60) | 18/32 (56) |
| ILIa | 17/43 (40) | 15/32 (47) |
Data are presented as n (%) or n/N (%) unless otherwise indicated. Abbreviations: ILI, influenza-like illness; RT-PCR, reverse transcriptase–polymerase chain reaction.
aFever with sore throat or cough.