H1n1 Web Update 2008-2009

Influenza A(H1N1) virus resistance to oseltamivir - 2008/2009 influenza season, northern hemisphere 18 March 2009 During weeks 1-4 (28 December 08 – 24 January 09), the level of overall influenza activity in the world increased. In Europe, most countries reported regional or widespread activity with influenza A (H3) viruses predominating. Widespread influenza A activity (H1 and H3) was reported in Japan. In Canada, Hong Kong SAR and the United States, influenza activity increased but remained relatively low. Sporadic influenza activity was observed in Brazil (A), Croatia (H1,H3, B), Greece (H1, H3, B), Iran (H1, H3), Mongolia (A), Portugal (H1, H3, B), Serbia (H1, H3, B), Singapore (H1, H3, B), Slovakia (H3) and Turkey (H3, B). During this period, a total of 30 countries from all WHO regions reported oseltamivir resistance for 1291 of 1362 A(H1N1) viruses analysed. The prevalence of oseltamivir resistance was very high in the following countries/territory: Canada (52 of 52 tested), Hong Kong SAR (72 of 80), Japan (420 of 422), the Republic of Korea (268 of 269) and the United States of America (237 of 241). The resistance prevalence was relatively low in China (6 of 44 tested). In Europe, H1N1 circulation was low during this period while the resistance prevalence was high: France (12 of 12 tested), Germany (66 of 67), Ireland (9 of 10), Italy (16 of 16), Sweden (11 of 12) and the United Kingdom (61 of 62). WHO is collecting global data about this phenomenon from multiple laboratories participating in Global Influenza Surveillance Network. Data from European countries participating in EISS were provided by the EISS and VirGil project. This summary table will be updated regularly (every four weeks). Oseltamivir resistance results were based on phenotypic and/or genotypic analyses. A comprehensive table of influenza A(H1N1)virus resistance to oseltamivir (Fourth quarter 2008 - 31 January 2009) can be found on the following page.

Table 1. Influenza A(H1N1) virus resistance to oseltamivir (Fourth quarter 2008 - 31 January 2009) as of 18 Mar 2009

Region

Country, area or territory

AFRO

Ghana Madagascar

AFRO Total AMRO

AMRO Total EMRO EMRO Total EURO

EURO Total SEARO SEARO Total WPRO

WPRO Total Grand Total

Argentina Canada Costa Rica Mexico Puerto Rico United States of America Marocco France Germany Greece Ireland Israel Italy Netherlands Norway Portugal Russian Federation Slovakia Spain Sweden United Kingdom India Thailand China China, Hong Kong SAR Japan Republic of Korea Singapore

No. of H1N1 isolates tested

1 7 8 1 52 1 5 1 241 301 10 10 12 67 1 10 1 16 4 9 3 6 1 5 12 62 209 6 6 12 44 80 422 269 7 822 1362

No.(%) of viruses tested positive for oseltamivir resistance†

1 0 1 0 52 0 4 1 237 294 10 10 12 66 1 9 1 16 4 9 3 5 1 5 11 61 204 6 5 11 6 72 420 268 5 771 1291

† Percentage (%) is not shown if the number of viruses tested was less than 10.

(100%)

(98%) (98%) (100%) (100%) (100%) (99%) (90%) (100%)

(92%) (98%) (98%)

(92%) (14%) (90%) (100%) (100%) (94%) (95%)

Table 2. Influenza A(H1N1) virus resistance to oseltamivir (1 April 2008 - 30 September 2008) as of 15Jan 2009

Region AFRO

AFRO Total AMRO

AMRO Total EMRO EMRO Total EURO

EURO Total SEARO SEARO Total WPRO

Country, area or territory

Cameroon Ghana Ivory Coast Kenya Madagascar Mauritius Nigeria Senegal Seychelles South Africa Argentina Brazil Canada Chile Colombia Costa Rica El Salvador Guadeloupe Guatemala Honduras Mexico Nicaragua Panama Paraguay Peru United States of America Uruguay Venezuela Jordan Netherlands Norway Russian Federation United Kingdom India Thailand Australia China, Hong Kong SAR Japan Malaysia New Caledonia New Zealand Philippines Singapore

No. of H1N1 No.(%) of viruses tested isolates positive for oseltamivir tested resistance†

2 22 5 9 9 1 1 10 8 225 292 36 18 2 90 1 19 32 1 5 8 3 13 9 1 9 10 17 1 275 2 2 2 8 20 1 31 1 12 13 76 583 7 8 7 2 11 6

2 13 2 1 0 1 1 10 5 225 260 18 4 1 12 0 14 21 0 4 5 1 0 0 0 0 3 14 1 98 1 1 1 6 9 1 17 0 0 0 71 97 1 0 7 2 10 3

(59%)

(100%) (100%) (89%) (50%) (22%) (13%) (74%) (66%)

(30%) (82%) (36%)

(45%) (55%)

(93%) (17%)

(91%)

Vietnam WPRO Total Grand Total

31 731 1344

21 (68%) 212 (29%) 588 (44%)

† Percentage (%) is not shown if the number of viruses tested was less than 10.