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Sustaining Polio Eradication

Sustaining Polio Eradication. The experience of polio-free countries with importations of WPV: Implications for India. IEAG March 2012. Lesson 1. Importations will happen Since 2000, 44 countries that had been polio free have suffered from one or more importations of wild poliovirus.

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Sustaining Polio Eradication

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  1. Sustaining Polio Eradication The experience of polio-free countries with importations of WPV: Implications for India IEAG March 2012

  2. Lesson 1 • Importations will happen • Since 2000, 44 countries that had been polio free have suffered from one or more importations of wild poliovirus

  3. Routes of travel associated with polio cases, 2001-2010 (10 years) 477 Viral origin: India Viral origin: Nigeria <100 cases 100  300 cases >300 cases Further spread Air / Sea routes Road 1 55 480 345 267 529 305 1 341* 5** * 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 Data at WHO HQ as of 24 January 2011

  4. The main factors affecting the chances of an outbreak The chances of importation - exposure to WPV Population immunity - the likelihood that imported virus will spread

  5. The main factors affecting the size & duration of an outbreak Speed of detection Speed of response Population immunity

  6. India has multiple risk factors for exposure to WPV Prior exporter – what goes out can come back…. Bordering / in proximity to 2 endemic countries Significant international population movement

  7. Lesson 2 • Maintain population immunity • Countries with better baseline immunity have smaller outbreaks and stop them more quickly

  8. Indonesia Last indigenous case: 1997 Outbreak: 2005 Size of outbreak: 303 cases Duration of outbreak: 13 months

  9. Bangladesh Last indigenous case: 2000 Outbreak: 2006 Size of outbreak: 18 cases Duration of outbreak: 8 months

  10. 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

  11. Maintaining immunity:differences in SIA schedules • Indonesia conducted only 2 national rounds in the four years prior to the outbreak; B'desh conducted 8.

  12. Lesson 3 • Maintain surveillance quality • Countries with better surveillance are more likely to find WPV / cVDPV faster

  13. 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

  14. Indonesia outbreak: epidemic curve and SIAs Mop-up 3 provinces 31 May Mop-ups 3 provinces 28 Jun Late detection & nearly 3 months onset to response NID 30 Aug NID 27 Sep NID 30 Nov SNID 30 Jan NID 22 Feb NID 12 Apr WPV1 positive contact in Aceh Tenggara 13 Apr WPV1 case in Aceh Tenggara 26 Feb 2005 2006 Data as of 24 July 2006

  15. Lesson 4 • Respond fast • Countries responding more quickly have shorter and smaller outbreaks

  16. China Last indigenous case: 1994 Outbreak: 2011 Size of outbreak: 21 cases Duration of outbreak: 3.5months

  17. 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

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

  19. Lesson 5 • Be flexible in response • Wider target age groups and short interval rounds may impact on size and duration of outbreaks

  20. Tajikistan Last indigenous case: 1994 Outbreak: 2010 Size of outbreak: 458 cases Duration of outbreak: 6 months

  21. Flexible response, Tajikistan 2010 SIA Round 2 mOPV1 (99.4%) SIA Round 3 mOPV1 (98.8%) SIA Round 4 mOPV1 (99.3%) Mop-up 13-17 Sep mOPV 34 districts (98-100%) SIA Round 5 tOPV SIA Round 6 tOPV SIA Round 1 mOPV1 (99.4%) 4 x Short interval rounds 3rd & 4th rounds expanded target age group

  22. Impact of age group immunizedMedian duration of outbreaks & # of rounds to control

  23. Lesson 5 • Assess and mitigate risks • Identifying risks allows for actions to minimize it

  24. Subnational polio risk assessmentWestern Pacific Region, 2011* LEGEND: Low risk Medium risk High risk * Source: country progress reports submitted to RCC17 (Nov 2011)

  25. Conclusion: risks for a polio free India • 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

  26. Conclusion: how can India be protected? • Eradicate all circulating poliovirus globally and certify eradication • Until then: • - Maintain high population immunity (routine plus SIAs) • - Maintain high quality surveillance & capacity to respond

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