Table 2.
Comparison between seroprevalence rates (Percent with HI ≥ 1:40), before and at the end of the pandemic period, stratified by age‐group
| Age‐group (years) | Pre‐pandemic (April–September 2008) | End of pandemic (February–March 2010) | Difference | ||||
|---|---|---|---|---|---|---|---|
| n | % Positivea | GMTb | n | % Positivea | GMTb | % Positivea | |
| 0–9 | 180 | 0·6 (0·0–1·6) | 10·1 (9·9–10·3) | 95 | 54·7 (44·7–64·7) | 54·7 (38·7–77·5) | 54·1 (44·1–64·2) |
| 10–19 | 186 | 28·0 (21·5–34·4) | 20·3 (17·2–23·9) | 110 | 60·9 (51·8–70·0) | 56·9 (42·3–76·6) | 32·9 (21·8–44·1) |
| 20–49 | 512 | 7·2 (5·0–9·5) | 11·9 (11·4–12·5) | 186 | 30·1 (23·5–36·7) | 24·9 (20·5–30·3) | 22·9 (15·9–29·8) |
| 50–79 | 532 | 6·0 (4·0–8·0) | 11·9 (11·4–12·4) | 216 | 20·8 (15·4–26·2) | 18·3 (15·7–21·2) | 14·8 (9·0–20·6) |
| 80+ | 90 | 40·0 (29·9–50·1) | 25·2 (20·8–30·4) | 41 | 46·3 (31·1–61·6) | 35·5 (25·0–50·5) | 6·3 (0–24·7) |
| All ages | 1500 | 9·9 (8·5–11·5) | 13·1 (12·6–13·5) | 648 | 38·4 (34·6–42·2) | 29·7 (26·5–33·2) | 28·5 (24·4–32·5) |
a
Data are % (95% confidence interval).
b
Geometric mean titer (95% confidence interval).