Table 2.
Influenza type and subtype RT-PCR testing results for patients presenting with influenza-like illness by year and age group—National Influenza Surveillance System, Vietnam, January 1, 2006–December 31, 2010.
| ILI a patients tested for influenza (%)b | Influenza, positive (%)b | A/H1 positive (%) | A/H3 positive (%) | B positive (%) | 2009 H1N1 positive (%) | |
|---|---|---|---|---|---|---|
| Total | 29,804 | 6516 (22) | 1298 (4.4) | 2249 (7.6) | 2163 (7.3) | 785 (2.6) |
| Year | ||||||
| 2006 | 4624 | 947 (20) | 574 (12) | 56 (1.2) | 315 (6.8) | – |
| 2007 | 6467 | 1167 (18) | 16 (0.3) | 875 (14) | 272 (4.2) | – |
| 2008 | 6954 | 1486 (21) | 641 (9.2) | 221 (3.2) | 617 (8.9) | – |
| 2009 | 7357 | 1937 (26) | 67 (0.9) | 718 (9.8) | 454 (6.2) | 691 (9.4) |
| 2010 | 4402 | 979 (22) | 0 | 379 (8.6) | 505 (11) | 94 (2.1) |
| Age groupsb | ||||||
| 0–15 years | 18,026 | 4129 (23) | 775 (4.3) | 1384 (7.7) | 1478 (8.2) | 482 (2.7) |
| 15–24 years | 3681 | 867 (24) | 166 (4.5) | 259 (7.0) | 256 (7.0) | 183 (5.0) |
| 25–64 years | 7187 | 1404 (20) | 329 (4.6) | 557 (7.8) | 390 (5.4) | 120 (1.7) |
| >64 years | 889 | 116 (13) | 28 (3.2) | 49 (5.5) | 39 (4.4) | 0 |
| Region | ||||||
| Northern | 10,258 | 2733 (21) | 630 (4.9) | 1023 (7.9) | 820 (6.3) | 246 (1.9) |
| Central | 6723 | 2037 (23) | 429 (4.9) | 619 (7.1) | 686 (7.8) | 297 (3.4) |
| Southern | 6307 | 1746 (22) | 239 (3.0) | 607 (7.6) | 657 (8.2) | 242 (3.0) |
a
ILI = influenza-like illness: fever (≥38 °C) with onset of either cough or sore throat ≤3 days prior to presentation.
b
12 patients had co-infection with seasonal influenza A (H3N2) and B viruses, 2 patients had co-infection with seasonal influenza A (H1N1) and B viruses, and 7 influenza positive patients had no reported subtype information.