Distribution of serum samples, number of children evaluated, and number of time points when at least one symptomatic respiratory infection was reported by parents
| Age stratum (yr) | No. of samplesa (%) (n = 1,024) | No. of children (%) (n = 50) | No. of time points (%) (n = 586) |
|---|---|---|---|
| 1st | 124 (12.1) | 48 (96) | 83 (14.2) |
| 2nd | 154 (15.0) | 50 (100) | 105 (17.9) |
| 3rd | 90 (8.8) | 50 (100) | 60 (10.2) |
| 4th | 95 (9.3) | 50 (100) | 57 (9.7) |
| 5th | 94 (9.2) | 50 (100) | 60 (10.2) |
| 6th | 95 (9.3) | 49 (98) | 63 (10.8) |
| 7th | 85 (8.3) | 47 (94) | 49 (8.4) |
| 8th | 89 (8.7) | 49 (98) | 46 (7.9) |
| 9th | 88 (8.6) | 48 (96) | 33 (5.6) |
| 10th | 52 (5.1) | 32 (64) | 17 (2.9) |
| 11th | 34 (3.3) | 22 (44) | 6 (1) |
| 12th | 19 (1.8) | 11 (22) | 6 (1) |
| 13th | 5 (0.5) | 4 (8) | 1 (0.2) |
↵a Some children had >1 serum sample analyzed in each age stratum.