Experiences with pre-emptive cholera vaccination in emergency situations

Transcription

1 Experiences with pre-emptive cholera vaccination in emergency situations Meeting on integrating vaccines into global cholera control efforts Les Pensières, Veyrier du Lac, France Dr Claire-Lise Chaignat

2 Public Health benefit of cholera vaccines? target vulnerable groups in high risk areas consider seasonality when usually recommended control measures limited Immunization Averted Cases & deaths

3 WHO prequalified Two Dose OCV (WC/rB killed) 1 Buffer Sachet 150ml Drinking Water 1 Vial of Vaccine Pictures: Darfur, Sudan, 2004

4 Cholera vaccine use in public health with WHO participation Zanzibar Jan-Feb 09 NO vaccine use Uganda FSM Beira Darfur /Aceh, Indonesia Goma, DRC WHO recommandations /04 WHO recommendations 2005 WHO recommandations

5 WHO Recommendations for Cholera Vaccine Use I. WHO meeting on use of OCV in emergencies, May 1999 OCV should be considered among tools to prevent cholera in populations at risk of an outbreak II. WHO meeting on the use of OCV, December 2002 vaccine use suggested in endemic and epidemic settings well designed demonstration projects III. WHO meeting on the use of OCV in complex emergencies, Cairo, December 2005 relevance of multidisciplinary approach context of broader public health priorities 3-step decision making tool developed (to be tested)

6 3-step decision making Decision making tool tree to assess for the OCV use in complex emergencies pertinence of OCV use in complex emergencies Step 1 Risk of cholera outbreak limited risk OCV use not relevant Risk exists Step 2 Capacity to contain potential outbreak good coping/ response capacities OCV use not relevant Limited capacity Step 3 Feasibility of OCV mass vaccination campaign not feasible OCV use not relevant feasible Immunization can be considered Draft

7 Feasibility and Context Natural disaster: infrastructure damaged loss of human resources limited access continuous threats political & economical disruption complex emergency with armed conflict endemic areas with seasonal outbreaks access (security, nat disasters)

8 Feasibility and logistics vaccine importation vaccine transport storage capacities cold chain water and cups waste disposal doses of vaccine with buffer: 7 100kg weight and 15.8m3 volume

9 Definitions (1) Public Health Emergency of International Concern (PHEIC/ IHR 2005): all public health events involving any 2 of the 4 criteria: serious public health event unusual or unexpected nature significant risk of international spread significant risk of restrictions on international travel or trade

10 Complex emergency: Definitions (1) large part of population affected, leading to potential massive population movements coping capacities of local and national authorities overwhelmed by magnitude of man-made or natural disaster numerous national and international actors may participate in relief efforts Reinforcement of several risk factors for cholera and CDS

11 Mythe : natural disasters - epidemics HOWEVER

12 Kalma camp, Darfur, July 2004 vulnerable population groups endemic cholera weakened healthcare system inadequacy in water and sanitation overcrowding.. volatile security.

13 Uganda OCV feasibility study, Sudanese refugees in Adjumani, N-Uganda Stable refugee situation doses of OCV administered 87% vaccine coverage after the second round 8% drop out between two rounds Very good acceptance except in younger children NB: 2008 cholera epidemic in the area, retrospective analysis showed low incidence in vaccinated refugees compared to non immunized

14 53'157 IDP's in 2 camps killed WCrB subunit OCV (2 doses) 1,2 million IDPs (Darfur) & refugees (E-Chad); water & sanitation not improving, considered at risk Rational for use: Outbreak in Chad spreading towards Sudanese border Cholera Mass Vaccination, S-Darfur, Sudan, 2004 July 2004

15 Results Cholera Vaccination Campaign Kalma Camp 2-6 YEARS > 6 YEARS Male Female Male Female Total 1st Round nd Round Coverage Coverage after 1st vaccination round 93% Coverage after 2nd vaccination round 88% Coverage 2nd round compared to 1st round 95% Drop out 1./2. round: 5% Excellent support from community leaders st Round 2nd Round Target Pop. Total

16 Post tsunami mass vaccination campaign Aceh Province, Indonesia, 2005, ( total target pop ; overall vaccine coverage 69%) Banda Aceh / Aceh Besar Target pop / Vaccine coverage 89%/ 58% 31 May - 26 June 2005 Aceh Jaya target pop vaccine coverage 88% 17 July 04.August 2005 Aceh Barat (Meulaboh) target pop vaccine coverage 71% (after 2.dose) April February - August 2005

17 Background Aceh Rational for use: perceived risk of occurrence by MOH Cholera in Aceh: surveillance data since 2002 only (no cases reported) Inofficial: last cholera cases 1997 WHO assessment: limited risk Proposal and request by MoH, Indonesia: Design: Phase 1,2,3 WHO to provide technical support for poreparation and implementation Evaluation after phase 1 to guide successive phases

18 Challenging, but possible: Full committment from MOH outcome 3 phased approach, redirect planning and implementaion according to field conditions EPI infrastructure and teams; WHO technical support team Carefull planning for implementation was critical Timing for implementation when less conflict with other public health priorities Showed the limits of mass vaccination with OCV High cost link between natural disasters and epidemics?

19 time frame comparison South Darfur Aceh, Indonesia Kalma Mussei Aceh Barat Banda Aceh, Aceh Besar Aceh Jaya Target population decision taken - start 1.dose 10 days 2.5 months 3.5 months 5 months Start preparation - end 2.dose 7 weeks 4 weeks 9 weeks 8 weeks 6 weeks Vaccine coverage 88% 71% 89% 58% 88%

20 risk assessment risk perception epidemiology : endemicity and AR trends over time living conditions overcrowding environmental management behaviour of community panic from threat of outbreak climatic conditions

21 available surveillance data availability of trends over time and hotspots ensure early detection of cholera cases / EWARN ensure follow-up surveillance cases Jan. Feb Mar Apr May June July Aug Sept. Oct Nov Dec

22 Evidence gathered from Aceh and Darfur OCV use is feasible, but requires important financial and human resources and can not be undertaken within very short time Pertinence of OCV use needs to be seriously evaluated in a given context, considering also different strategies to prevent and contain outbreaks. Field realities often differ from first impression In disasters many health issues are triggered simultaneously, requiring early assessment for a pertinent allocation of funds and human resources Psychological, political and cultural determinants should not be underestimated, may impact on risk perception and measures to counter them

23 Oral cholera vaccination in emergencies When? Pre-emptive / during an outbreak /routine immunization Complex emergency, natural disaster, stable situation Where? open setting, camps, way stations, detention centres, ring vaccination Whom? Vulnerable populations in endemic settings IDPs, refugees, pilgrims, detainees