Table 1.
Comparison of geography, demographics and main features of influenza surveillance systems of participating countries (from southern- to northernmost). The Global Influenza B Study
| Country | Latitude | Population (millions)* | Representativeness of data | Patients sampled | Denominator | Laboratory methods for influenza diagnosis | Laboratory methods for virus characterization | Isolates sent to WHO for reference |
|---|---|---|---|---|---|---|---|---|
| New Zealand | 41°81′S | 4·5 | Regional | Outpatients, inpatients, SARI | ILI/population | Sequencing | Isolates sent to WHO for reference | Yes |
| Chile | 35°82′S | 16·3 | National | Outpatients, inpatients, SARI | None | PCR, culture | Hemagglutination inhibition, sequencing | Yes |
| Argentina (Santa Fe) | 31°38′S | 3·2 | Regional | Outpatients, SARI | ILI/population | PCR, immunofluorescence | Isolates sent to WHO for reference | Yes |
| South Africa | 29°05′S | 53·0 | Regional | SARI | None | PCR | Sequencing | Yes |
| Australia | 25°85′S | 23·4 | National | Outpatients, SARI | ILI/consultations | PCR, serology, culture | Hemagglutination inhibition, sequencing | Yes |
| Madagascar | 19°43′S | 21·3 | Regional (until 2008), national (afterwards) | Outpatients | ILI/consultations | PCR, culture | Hemagglutination inhibition | Yes |
| Brazil | 10°83′S | 201·0 | National | Outpatients, SARI | ILI/consultations | PCR, immunofluorescence | Hemagglutination inhibition, sequencing | Yes |
| Indonesia | 1°66′S | 249·9 | National | Outpatients, inpatients, SARI | None | PCR, culture | Hemagglutination inhibition, sequencing | Yes |
| Singapore | 1°22′N | 5·4 | National | Outpatients | ARI/consultations | PCR | Hemagglutination inhibition, sequencing | Yes |
| Kenya | 0°42′S | 44·4 | Regional | Outpatients, SARI | ILI/population | PCR | Isolates sent to WHO for reference | Yes |
| Cameroon | 5°68′N | 20·4 | Regional | Outpatients, SARI | None | PCR | Hemagglutination inhibition | Yes |
| Ivory Coast | 7°61′N | 23·2 | Regional | Outpatients, SARI | None | PCR, culture | Hemagglutination inhibition | Yes |
| Panama | 8°57′N | 3·7 | National | Outpatients, SARI | None | PCR, culture, immunofluorescence | Isolates sent to WHO for reference | Yes |
| Costa Rica | 10°01′N | 4·6 | National | Outpatients, SARI | None | PCR, culture, immunofluorescence | Isolates sent to WHO for reference | Yes |
| Nicaragua | 12°86′N | 6·1 | National | Outpatients, SARI | None | PCR, culture, immunofluorescence | Isolates sent to WHO for reference | Yes |
| El Salvador | 13°78′N | 6·1 | National | Outpatients, SARI | None | PCR, culture, immunofluorescence | Isolates sent to WHO for reference | Yes |
| Honduras | 14°84′N | 8·2 | National | Outpatients, SARI | None | PCR, culture, immunofluorescence | Isolates sent to WHO for reference | Yes |
| Guatemala | 15°74′N | 15·4 | National | Outpatients, SARI | None | PCR, culture, immunofluorescence | Isolates sent to WHO for reference | Yes |
| Vietnam | 16°69′N | 89·7 | National | Outpatients, SARI, other | ILI/consultations | PCR, culture | Hemagglutination inhibition, sequencing | Yes |
| Bhutan | 27°40′N | 0·7 | National | Outpatients, SARI | ILI/consultations | PCR | Isolates sent to WHO for reference | Yes |
| China (south) | 31°12′N | 769·0 | National | Outpatients | ILI/consultations | PCR, culture | Hemagglutination inhibition | Yes |
| Turkey | 39°02′N | 76·7 | Regional | Outpatients | None | PCR, culture | Hemagglutination inhibition | Yes |
| China (north) | 39°54′N | 563·8 | National | Outpatients | ILI/consultations | PCR, culture | Hemagglutination inhibition | Yes |
| Italy | 42°88′N | 60·0 | National | Outpatients, inpatients, SARI | ILI/population | PCR | Hemagglutination inhibition, sequencing | Yes |
| United States | 45°62′N | 317·7 | National | Outpatients, inpatients, SARI | ILI/consultations | PCR, culture | Hemagglutination inhibition, sequencing | Yes |
| Ukraine | 49°06′N | 44·6 | National | Outpatients, SARI | ILI/population | PCR, culture | Hemagglutination inhibition | Yes |
| England | 52°33′N | 53·0 | National | Outpatients, inpatients | None | PCR, culture | Hemagglutination inhibition, sequencing | Yes |
ARI, acute respiratory infection; ILI, influenza-like illness; PCR, polymerase chain reaction; SARI, severe acute respiratory infection; WHO, World Health Organization.
*
Most recent estimate.