Cholera Vaccine use: The public health perspective€¦ · The public health perspective Strategic Advisory Group of Experts on Immunization 28 October, 2009 . Ad-hoc group of experts

Ad-hoc group of experts on cholera vaccines 28 October 2009

Dominique Legros, MD MPH

WHO

Cholera Vaccine use: The public health perspective

Strategic Advisory Group of Experts on Immunization

28 October, 2009


Introduction

  Improvements in sanitation and access to clean water –  The mainstays of preventing endemic and epidemic cholera –  "Sanitary revolution" of the 19th century –  Situation in least developed countries today

  Methods of prevention and control of cholera –  Preventing / reducing spread of the disease –  Reducing mortality

  Limitations of current methods

  Vaccination with oral cholera vaccines as an additional public health tool to reduce the risk of infection


Cholera prevention and control - reducing mortality

  Early case detection

  Increase access to health care (treat cases promptly)

  Adequate patients care –  Adapted health care infrastructures (decentralised, separate

cholera patients) –  ORS and IV fluids –  Antibiotics –  Feeding practices


Cholera prevention and control - Preventing / reducing spread

  Early detection of epidemics

  Safe water : piped water system, water treatment, safe water storage and use

  Excreta disposal : latrines and sewerage systems, culturally acceptable, affordable, easy to maintain

  Hand washing with soap

  Safe food

  Health Education / Social mobilization for behaviour change

  Infection control practices


Limitations of prevention and control methods

 Cholera often affects the poorest of the poor –  Access to those groups (geographical, security, cultural, etc.) –  Reduced access to health care

 Quality of health care in areas regularly affected by outbreaks or endemic

–  Investment in health system

  Access to ORS

 Resistance to antibiotics


  Large outbreaks and scale of the intervention –  Burden on health care system –  Heavy water & sanitation interventions (i.e. water trucking)

  Investments to built sewerage or piped water systems

 Changing behaviours –  Difficulty –  Sustainability

Limitations of prevention and control methods (2)


Vaccination with oral cholera vaccines

  As an additional strategy for endemic and epidemic cholera situations to reduce the risk of infection

  Synergistic with water and sanitation interventions


Current WHO recommendations for the use of Cholera Vaccines

  The use of OCV should be recommended in "certain endemic situations"

  The use of OCV should be complementary to existing strategies for cholera control and, in complex emergencies, should not interfere with "other critical public health interventions"

  Vaccination with the current internationally available prequalified vaccine (2005) is not recommended once a cholera outbreak has started

  Demonstration projects using oral cholera vaccines should be implemented


DUKORAL®: Feasibility of Mass Vaccination Campaigns

Location # of Doses

  Uganda1 1997 63,220

  Mayotte 2000 93,000

  Mozambique2 2003/04 82,000

  Darfur3 2004 103,000

  Indonesia 2004 137,000

  Zanzibar 2009 100,000

1 Legros D, et al. Bull World Health Organ 1999;77:837-42. 2 Lucas M et. al. N Engl J Med 2005; 352: 757-67. 3 WHO. Darfur Disease Outbreak control Bulletin. 2004 Aug 15. Available at: www.who.int/disasters/repo/14372.pdf.


Demonstration project in a highly endemic setting in Africa, Mozambique, 2003/04

•  Partnership: MOH; MSF/Epicentre; IVI; WHO

•  Killed WC-rBS oral cholera vaccine (2 doses)

•  44,878 people vaccinated

•  Vaccine coverage of the target population was 53.6% (after 2nd dose)

•  Mass vaccination campaign before the season was feasible and acceptable

•  Vaccine effectiveness 78%

Cavailler et al. Vaccine 2006 and Lucas M et al. NEJM 2005


Field experience in Zanzibar, 2009

  Target population 50,000 subjects (>2 yrs) –  100,000 doses provided –  1st round – 11-26 January 2009 (9 outposts) –  Inter-round interval of 12 days –  2nd round – 7-16 February 2009 (9 outposts)

 Mass cholera vaccination –  Feasible and well accepted –  In the short-term: scale-up vaccination

throughout Zanzibar


Pre-emtive vaccination in complex humanitarian emergencies, Kalma camps, Darfur, Sudan

●  53,537 internally displaced persons (IDP's) in 2 camps

●  103,000 doses provided of the killed WC-rBS oral cholera vaccine (2 doses)

●  Estimated vaccine coverage 88% ●  42,878 received 1 st dose ●  40,388 received 2nd dose. ●  13,400 vaccinated in one day

WHO. Darfur Disease Outbreak control Bulletin. 2004 Aug 15. Available at: www.who.int/disasters/repo/14372.pdf.


OCV - Recent developments and their Public Health consequences

 Well accepted by the populations in both endemic and epidemic settings

 Herd protection to non-vaccinated individuals

 No buffer for administration –  Reduced logistic constraints –  More flexible vaccination strategies

 Reasonable price –  Increased access for countries


Vaccination Strategies

  Vaccination strategy to be adapted to each context –  Based on the epidemiological pattern of cholera, the capacity of

the immunization program and health system, the capacity to organize a mass campaign, the specific economic and cultural conditions, etc.

  In endemic situations –  Universal vaccination throughout the country is probably not

warranted in most places –  Periodic mass vaccination campaigns targeted at high risk

populations / regions are the most practical option –  Re- vaccination may be required every 2 years


Vaccination Strategies

  In outbreak situations –  Pre-emptive vaccination targeting populations with limited access

to safe water or sanitation –  Reactive vaccination in areas not yet affected during large

outbreaks –  Investigation of the current and historical epidemiological situation

and identification of areas/populations to be targeted –  Treatment of cases, water and sanitation interventions, and

community mobilization : the mainstays of control measures


Summary

  Public Health prevention and control measures of cholera well known since decades but with limitations

  Vaccination with oral cholera vaccine as an additional prevention strategy for endemic and epidemic cholera situations

 Recent OCV developments should facilitate their use as a public health tool with adapted vaccination strategies

Documents

Cholera Vaccine use: The public health perspective€¦ · The public health perspective Strategic Advisory Group of Experts on Immunization 28 October, 2009 . Ad-hoc group of experts