4th Global Meeting on Implementing New and Under-utilized Vaccines, 23-25 June 2010
Workgroup 6. Vaccines of regional importance: typhoid and cholera
Background
Both cholera and typhoid fever are caused by food- and water-borne enteric pathogens, and both diseases thrive under conditions of poor drinking water quality, sanitation and hygiene. Annual global estimates of mortality for each disease are substantial, ca. 100,000 deaths due to cholera and ca. 220,000 deaths due to typhoid. But even among developing countries the geographical distributions of these diseases are heterogeneous. And even within countries, only sub-populations may be at risk. Both diseases occur predictably in certain populations as endemic disease. However, adding to the complexity of the spatial-temporal disease distribution is the tendency, especially for cholera, for epidemic disease to occur unpredictably.
Until recently, efforts to prevent these diseases focused primarily on provision of improved water and sanitation, to the exclusion of vaccines. Recent developments in new vaccines against both diseases, as well as recent better appreciation of the value of vaccines that were developed and licensed in the 1980s, have led to a reappraisal of the role of these vaccines in disease control, including revised recommendations for the use of cholera and typhoid vaccines by WHO. A major challenge for the implementation of these vaccines is the fact that both children and adults are at risk for these diseases, raising the need for innovative vaccine delivery systems. Furthermore, strategies for use of the vaccines in epidemics may differ substantially from those needed for control of endemic disease.
Main Topics of Discussion
- Given that cholera and typhoid are diseases that affect similar populations in similar environments, an integrated approach is necessary where appropriate. Although clean water and sanitation are mainstays for control, vaccines are now available as additional tools.
- Given that both diseases require a risk-based approach for vaccination, surveillance data for decision-making at the country level are very important.
- Not having a simple and accurate tool to diagnose typhoid makes it difficult to have accurate surveillance and burden of disease data.
- It was noted that for many countries, there was stigma and thus, disincentive to report cholera and typhoid outbreaks.
- Typhoid and cholera impact the most disadvantaged groups who lack political influence so there is a need to have champions to fight for the cause for the poor and to improve communication on these diseases both for national decision makers and global communities.
- The strategies for the deployment of vaccines at the country level include preventive, pre-emptive & reactive campaigns
- For both diseases there is need to improve risk assessment tools and approaches.
- In order to enhance the global availability of vaccines, WHO prequalification is an important pre-requisite.
- Following the development of an investment case for cholera, it is suggested that country-by-country financing and vaccination strategies may be needed
- A combined vaccine for the two diseases may be an important future research priority.
Recommendations
- Identify champions and early adopters for vaccine introduction
- Support countries to strengthen surveillance for these diseases; develop better tests to more accurately diagnose typhoid; need to better describe burden of disease due to typhoid and cholera
- Develop approach and standards for monitoring vaccine coverage and impact
- Obtain feedback from countries on the investment cases and use to develop resource mobilization tool
- Support WHO prequalification of typhoid and cholera vaccines
- Support research efforts to develop/improve products
- Conjugate typhoid vaccine
- Improved schedule (e.g., single dose, efficacy in 9 month)