Sustaining Polio Eradication

IEAGMarch 2012

The experience of polio-free countries with importations of WPV:

Implications for India

Importations will happen• Since 2000, 44 countries that

had been polio free have suffered from one or more importations of wild poliovirus

Lesson 1

477

345 267 529

480

305

55

Data at WHO HQ as of 24 January 2011

Routes of travel associated with polio cases, 2001-2010 (10 years)

341*

1

* 341 confirmed cases (2001-2010), however 540 AFP cases are pending classification in the Congo from the 2010 outbreak.

** 5 WPV cases into Zambia in 2001-2002 from indigenous transmission in Angola

Air / Sea routes

Road

Viral origin: India

Viral origin: Nigeria

<100 cases

100 300 cases

>300 cases

Further spread

1

5**

The chances of importation - exposure to WPV

Population immunity - the likelihood that imported virus will spread

The main factors affecting the chances of an outbreak

Speed of detection

Speed of response

Population immunity

The main factors affecting the size & duration of an outbreak

Prior exporter – what goes out can come back….

Bordering / in proximity to 2 endemic countries

Significant international population movement

India has multiple risk factors for exposure to WPV

Maintain population immunity• Countries with better baseline

immunity have smaller outbreaks and stop them more quickly

Lesson 2

Last indigenous case: 1997

Outbreak: 2005

Size of outbreak: 303 cases

Duration of outbreak: 13 months

Indonesia

Last indigenous case: 2000

Outbreak: 2006

Size of outbreak: 18 cases

Duration of outbreak: 8 months

Bangladesh

The difference immunity makes:% Under Immunized Non-polio AFP Cases

(< 5 Yrs) the year of the outbreak

• Indonesia had a far larger immunity gap in 2005 than Bangladesh in 2006

• Indonesia had a much larger outbreak and took longer to stop it

0

5

10

15

20

25

30

35

40

Indonesia B'desh

% < 3doses

Maintaining immunity:differences in SIA schedules

• Indonesia conducted only 2 national rounds in the four years prior to the outbreak; B'desh conducted 8.

0

1

2

3

4

5

2001 2002 2003 2004

Indo B'desh

Maintain surveillance quality• Countries with better surveillance are

more likely to find WPV / cVDPV faster

Lesson 3

The difference surveillance makes:Non-polio AFP rates the year before the outbreak

• Indonesia had a less sensitive surveillance system in 2004 than Bangladesh in 2005

• Indonesia took longer to detect and respond to the outbreak

0

1

2

3

4

Indonesia B'desh

NP AFPrate

0

4

8

12

16

20

24

28

32

36

40

44

48

526-

12 M

ar

20-2

6 M

ar

3-9

Apr

17-2

3 A

pr

1-7

May

15-2

1 M

ay

29 M

ay-4

Jun

12-1

8 Ju

n

26 J

un-2

Jul

10-1

6 Ju

l

24-3

0 Ju

l

7-13

Aug

21-2

7 A

ug

4-11

Sep

20-2

6 S

ep

4 -

10 O

ct

18-2

4 O

ct

1-7

Nov

15 -

21

Nov

29 N

ov-5

Dec

13-1

9 D

ec

27 D

ec -

2 J

an

10-1

6 Ja

n

24-3

0 Ja

n

6-12

Feb

20-2

6 F

eb

6-12

Mar

20-2

6 M

ar

3-9

Apr

17-2

3 A

pr 2

4-30

Apr

Indonesia outbreak: epidemic curve and SIAs

Data as of 24 July 2006

2005

Mop-up 3 provinces31 May

Mop-ups 3 provinces 28 Jun

NID 30 Aug

NID 27 Sep

NID 30 Nov

SNID 30 Jan

NID 22 Feb

NID 12 Apr

WPV1 positive contact in Aceh Tenggara13 Apr

2006

WPV1 case in Aceh Tenggara26 Feb

Late detection & nearly 3 months onset to response

Respond fast• Countries responding more quickly

have shorter and smaller outbreaks

Lesson 4

Last indigenous case: 1994

Outbreak: 2011

Size of outbreak: 21 cases

Duration of outbreak: 3.5 months

China

Polio outbreak China - key timeline• 6 July: Onset of first case

• 24 August: Preliminary lab result of WPV

• 26 August: Level 2 public health emergency announced; Notification thru IHR

• 27 August: Vice Minister Health, China flies to Xinjiang

Video conference with all prefectures and counties

• 28 August: >90 China CDC experts from around country arrive

• 30 August: Emergency plan launched

• 1 September: TV promotion campaign begins

• 2 September: 5m doses of tOPV arrive by China Air Force cargo plane

• 3 September: Training of > 1000 staff for SIA and surveillance

• 7 September: Video conference with 2300 political leaders

• 8 September: Start of 1st SIA covering >4 million children

Launched in Hotan prefecture by Minister of Health, China

15 days

Impact of speed of response 2009-11 Median duration of outbreaks & # of rounds to control

0

5

10

15

20

25

Overallaverage

SIA < 6weeks of

onset

SIA > 6weeks of

onset

Weeks Rounds

Be flexible in response• Wider target age groups and short

interval rounds may impact on size and duration of outbreaks

Lesson 5

Last indigenous case: 1994

Outbreak: 2010

Size of outbreak: 458 cases

Duration of outbreak: 6 months

Tajikistan

Flexible response, Tajikistan 2010

SIARound 1mOPV1(99.4%)

SIARound 2mOPV1(99.4%)

SIARound 3mOPV1(98.8%)

SIARound 4mOPV1(99.3%)

Mop-up13-17 Sep mOPV 34 districts(98-100%)

SIARound 5tOPV

SIARound 6tOPV

4 x Short interval rounds

3rd & 4th rounds expanded target age group

Impact of age group immunized Median duration of outbreaks & # of rounds to control

0

5

10

15

20

25

Overallaverage

> 5 years < 5 years

Weeks Rounds

Assess and mitigate risks• Identifying risks allows for actions to

minimize it

Lesson 5

Subnational polio risk assessmentWestern Pacific Region, 2011*

Low risk

Medium risk

High risk

LEGEND:

* Source: country progress reports submitted to RCC17

(Nov 2011)

• Historically, the risk of a significant outbreak in any country following cessation of indigenous transmission has increased over time

• Why?

– Population immunity wanes

– Surveillance quality deteriorates

– Experience is lost

Conclusion: risks for a polio free India

• Eradicate all circulating poliovirus globally and certify eradication

• Until then:

- Maintain high population immunity (routine plus SIAs)

- Maintain high quality surveillance & capacity to respond

Conclusion: how can India be protected?