Table 3.
Influenza positive RT-PCR testing results by type, region, and overall for patients presenting with influenza-like illness at any time, during the months of northern hemispherea vaccine formulation availability, and during the months of southern hemispherea vaccine availability—National Influenza Surveillance System, Vietnam, January 1, 2006–December 31, 2010†.
| Region influenza type | Influenza positive RT-PCR testing from patients presenting with ILI
|
||
|---|---|---|---|
| Northern hemispherea vaccine formulation availability (November–April) (% of entire year) | Southern hemispherea vaccine formulation availability (May–October) (% of entire year) | Entire year (January–December) | |
| Northern region | 809 (33) | 1664 (67) | 2473 |
| A, all seasonal subtypes | 347 (21) | 1306 (79) | 1653 |
| B | 462 (56) | 358 (44) | 820 |
| Central region | 811 (47) | 1815 (53) | 2037 |
| A, all seasonal subtypes | 328 (31) | 720 (69) | 1048 |
| B | 483 (70) | 203 (30) | 686 |
| Southern region | 496 (33) | 1007 (67) | 1503 |
| A, all seasonal subtypes | 159 (19) | 687 (81) | 846 |
| B | 337 (51) | 320 (49) | 657 |
| All regions, A and B | 2116 (37) | 3594 (63) | 5710 |
| A, all seasonal subtypes | 834 (24) | 2713 (76) | 3547 |
| B | 1282 (59) | 881 (41) | 2163 |
Influenza-like illness, by World Health Organization (WHO): fever (≥38 °C) with either cough or sore throat, and onset of symptoms ≤3 days.
As designated by the World Health Organization, based on surveillance of circulating strains in each hemisphere.
Testing for influenza was done through polymerase-chain reaction on pharyngeal swabs, excludes those testing positive for 2009 H1N1. Two patients had co-infection with seasonal influenza A (H1N1) and B viruses, 12 patients had co-infection with influenza A (H3N2) and B viruses, eight were not subtyped, and one had no subtyping information available.