Table 2.
Annual seroprevalence to each influenza A virus subtypes tested (n = 1147)
| Year | No. of sera | HI positivity rate to different influenza virus antigens | |||||||
|---|---|---|---|---|---|---|---|---|---|
| H1(%) | 95%CI | H3(%) | 95%CI | A(H1N1) pdm09(%) | 95%CI | H5(%) | 95%CI | ||
| 2006 | 393 | 5·6 | 3·5–8·4 | 2·3 | 1·1–4·3 | NT | – | 0* | 0·0–12·8 |
| 2007 | 113 | 2·7 | 0·6–7·6 | 0·0 | 0·0–3·2 | NT | – | NT | – |
| 2008 | 269 | 46·5 | 40·4–52·6 | 33·8 | 28·2–39·8 | NT | – | 0* | 0·0–7·0 |
| 2009 | 36 | 19·4 | 8·2–36·0 | 13·9 | 4·7–29·5 | 0·0 | 0·0–9·7 | 0* | 0·0–9·7 |
| 2010 | 336 | 12·5 | 9·2–16·5 | 2·4 | 1·0–4·6 | 25·6 | 21·0–30·6 | 0* | 0·0–9·7 |
*Only a subset of the samples were tested for antibodies against H5N1 virus.
NT, not tested; HI, hemagglutination inhibition assay.