Table 1.
Seropositive proportion by age group, before and after first and second pandemic waves
| Age group (years) | Number of seropositive samples/total samples per group [Proportion (95% CI)] |
|||
|---|---|---|---|---|
| Pre-first wave April/May 2009 | Post-first wave November 2009 | Pre-second wave March/April 2010 | Post-second wave November 2010 | |
| 16–24 | 14/74 0·19 (0·11, 0·30) |
51/138 0·40 (0·29, 0·46)** |
110/225 0·49 (0·42, 0·56) * |
71/140 0·51 (0·42, 0·59) |
| 25–34 | 4/59 0·07 (0·02, 0·16) |
31/139 0·22 (0·16, 0·30)** |
56/136 0·41 (0·33, 0·50)** |
53/140 0·38 (0·30, 0·46) |
| 35–44 | 8/64 0·13 (0·06, 0·23) |
20/131 0·15 (0·09, 0·23) |
45/139 0·32 (0·25, 0·41) * |
61/140 0·44 (0·35, 0·52) * |
| 45–54 | 12/129 0·09 (0·05, 0·16) |
22/138 0·16 (0·10, 0·23) |
45/140 0·32 (0·25, 0·41)** |
52/139 0·37 (0·29, 0·46) |
| 55–64 | 16/129 0·12 (0·07, 0·20) |
26/131 0·20 (0·13, 0·28) |
67/148 0·45 (0·37, 0·54)** |
58/140 0·41 (0·33, 0·50) |
| >65 | 5/27 0·19 (0·06, 0·38) |
25/102 0·25 (0·17, 0·34) |
104/198 0·53 (0·45, 0·60) ** |
56/140 0·40 (0·32, 0·49) * |
| Total | 59/496 0·12 (0·09, 0·15) |
175/779 0·22 (0·20, 0·26) ** |
427/986 0·43 (0·40, 0·46) ** |
351/839 0·42 (0·38, 0·45) |
*
Significant change from previous timepoint, P ≤ 0·05.
**
Significant change from previous timepoint, P < 0·005.