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Situation UpdateInfluenza A (H1N1), 26 May 09

Situation UpdateInfluenza A (H1N1), 26 May 09

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Age distribution of confirmed new influenza A (H1N1) cases in Mexico and United States, 2009 (cases reported to 12 May)

Age distribution of confirmed new influenza A (H1N1) cases in Mexico and United States, 2009 (cases reported to 12 May)

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Cumulative No. of cases and countries reporting Influenza A (H1N1)

0

5

10

15

20

25

30

35

40

45

50

Date of report

No

of c

ount

ries

rep

ortin

g

0

2000

4000

6000

8000

10000

12000

14000

Num

ber

of c

onfir

med

cas

es

Public health emergency of international concern

Pandemic Phase 4

Pandemic Phase 5

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Reasons for concern about Influenza A (H1N1)

Reasons for concern about Influenza A (H1N1)

New strain- combination of swine-avian-human influenza viruses

Evidences for sustained human-to-human infection – cases with no evidence of exposure other than infected humans

(most cases reported so far)– clusters of cases in family members (USA, Mexico)

Young people; median age of cases: 22 years

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Influenza A (H1N1): VirologyInfluenza A (H1N1): Virology

Reassortment - four different genes:– North America swine– Asia/Europe swine– Human influenza– Avian (Non H5)

Unique combination that has never been seen before

Level of immunity in general community – Unknown, probably limited or none

Effectiveness of seasonal influenza vaccine– Unknown

Antiviral resistance– Resistant to amandatines– Sensitive to oseltamivir (tamiflu) and zanamivir (relenza)

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Pandemic Phases Pandemic Phases

1 - 3

SustainedH-2-H

transmission

Time

Predominantly animalinfections; Limited infections of people

Geographic spread

5 - 6

4

PostPeak

PostPandemic

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Phase 5Phase 5

Phase 5 is characterized by the same identified virus that has caused sustained community level outbreaks into at least two countries in one WHO region.

the declaration of Phase 5 is a strong signal that a pandemic is imminent

the time to finalize the organization, communication, and implementation of the planned mitigation measures is short;

Each country should implement actions as called for in their national influenza pandemic preparedness plans.

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Phase 5 to Phase 6Phase 5 to Phase 6

Phase 6 is characterized by community level outbreaks in at least one other country in a different WHO region by the same virus

Designation of this phase will indicate that a global pandemic is under way.

Means expansion to newer area not an indication of it’s severity

Member countries should review surge capacity and emphasize measures to reduce the spread of disease

Surge capacity: in the area of surveillance, rapid detection, lab diagnosis, hospital and health centres, community awareness and empowerment etc.

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Lesson learned so far…Lesson learned so far…

Past experiences show influenza viruses spread fast and far (such as seen in 1918, 1957, 1968)

Pandemic influenza may be observed in several waves, i.e. milder form to severe form

Need to review Pandemic Preparedness Plan which were developed with AI (H5N1) in mind; H5N1 still around

Miscommunication and misinterpretation of the events are a real challenge, i.e. travel ban, culling of pigs, import ban and remove pork from menu

Knowledge gaps exist on current pandemic from novel influenza A (H1N1)- as it is evolving

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Influenza SeasonalityInfluenza SeasonalityInfluenza SeasonalityInfluenza Seasonality

0

4

8

12

16

20

24

28

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Winter Summer Rainy Season

Pune (west)

0

4

8

12

16

20

24

28

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Winter Summer Rainy Season

Kolkota (east)

-1

3

7

11

15

19

23

27

31

35

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Summer Winter Rainy Season

Chennai (south)

0

4

8

12

16

20

24

28

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Winter Summer Rainy Season

Delhi (north)

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WHO/SEARO Response WHO/SEARO Response

Situation monitoring and assessment

Technical guidance

Capacity building: surveillance and laboratory diagnosis

Vaccine and antivirals

Communication– media briefing, interviews, web updates etc

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Visit us at: http://www.searo.who.int/h1n1