Table 2.
Indirect effectiveness for household contacts of influenza vaccinated children compared with controls (from Esposito et al., 2003).
| Event | Contacts of vaccinated children (n = 176) |
Contacts of controls (n = 173) |
Indirect effectiveness (%) |
P-value |
|---|---|---|---|---|
| No. of respiratory tract infections | 2.19 ± 0.99 (2) | 2.90 ± 1.68 (3) | 24 | <0.0001 |
| Parents | 1.77 ± 1.01 (2) | 2.26 ± 1.40 (2) | 22 | <0.0001 |
| Siblings | 3.29 ± 0.54 (3) | 4.59 ± 1.81 (6) | 29 | <0.0001 |
| No. of medical visits for respiratory illness | 1.25 ± 1.24 (1) | 2.06 ± 0.99 (2) | 39 | <0.0001 |
| Parents | 1.08 ± 1.26 (1) | 1.86 ± 0.92 (2) | 42 | <0.0001 |
| Siblings | 1.68 ± 1.10 (1) | 2.57 ± 0.99 (3) | 35 | <0.0001 |
| Loss of parental work days | 0.42 ± 0.88 (0) | 2.50 ± 2.31 (2) | 84 | <0.0001 |
| Mothers | 0.66 ± 1.88 (1) | 4.05 ± 2.34 (4) | 83 | <0.0001 |
| Fathers | 0.19 ± 0.37 (0) | 0.97 ± 2.24 (1) | 80 | <0.0001 |
| Missed school days of siblings | 1.31 ± 2.40 (1) | 2.76 ± 4.42 (3) | 53 | 0.001 |
Mean values ± S.D (median in parentheses)