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Mengel M.A.,Agence de Medecine Preventive
Transactions of the Royal Society of Tropical Medicine and Hygiene | Year: 2014

Cholera remains a grave public health problem in Africa. It is endemic with seasonal variations around the central African Great Lakes. Along the coasts, it occurs mostly in rapidly expanding epidemics, with intercalated 3-5 year lull-periods. Case-fatality ratios remain high at 2-5% against the global declining trend. Insufficient safe water and sanitation coverage are the main causes of persistent cholera in Africa and this is unlikely to improve soon. However, an efficacious oral cholera vaccine is now available and new groups and initiatives like the African Cholera Surveillance Network (Africhol) allow countries to enhance their capacities for an integrated cross-border approach using all means necessary to tackle cholera in Africa. © The Author 2014. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved.

Gessner B.D.,Agence de Medecine Preventive | Duclos P.,World Health Organization | Nelson E.A.S.,Chinese University of Hong Kong
Vaccine | Year: 2010

This supplement of Vaccine contains detailed descriptions of the experiences and processes of 15 well-established National Immunization Technical Advisory Committees from all regions of the world. All of these committees provide information to national governments that is used to make evidence-based decisions regarding vaccine and immunization policy. Nevertheless, many differences between committees exist including their legal basis, size and scope of committee membership, scope of work, role of the Ministry of Health on the committee, existence of conflict of interest policies, and ultimate role in the decision-making process. Individual country authors identified numerous areas for improvement and these are summarized here. © 2010 Elsevier Ltd. All rights reserved.

Griffiths U.K.,London School of Hygiene and Tropical Medicine | Clark A.,London School of Hygiene and Tropical Medicine | Gessner B.,Agence de Medecine Preventive | Miners A.,London School of Hygiene and Tropical Medicine | And 3 more authors.
Epidemiology and Infection | Year: 2012

Global coverage of infant Haemophilus influenzae type b (Hib) vaccination has increased considerably during the past decade, partly due to GAVI Alliance donations of the vaccine to low-income countries. In settings where large numbers of children receive only one or two vaccine doses rather than the recommended three doses, dose-specific efficacy estimates are needed to predict impact. The objective of this meta- Analysis is to determine Hib vaccine efficacy against different clinical outcomes after receiving one, two or three doses of vaccine. Studies were eligible for inclusion if a prospective, controlled design had been used to evaluate commercially available Hib conjugate vaccines. Eight studies were included. Pooled vaccine efficacies against invasive Hib disease after one, two or three doses of vaccine were 59%, 92% and 93%, respectively. The meta- Analysis provides robust estimates for use in decision- Analytical models designed to predict the impact of Hib vaccine. © 2011 Cambridge University Press.

Gessner B.D.,Agence de Medecine Preventive | Feikin D.R.,International Vaccine Access Center | Feikin D.R.,Centers for Disease Control and Prevention
Vaccine | Year: 2014

Traditionally, vaccines have been evaluated in clinical trials that establish vaccine efficacy (VE) against etiology-confirmed disease outcomes, a measure important for licensure. Yet, VE does not reflect a vaccine's public health impact because it does not account for relative disease incidence. An additional measure that more directly establishes a vaccine's public health value is the vaccine preventable disease incidence (VPDI), which is the incidence of disease preventable by vaccine in a given context. We describe how VE and VPDI can vary, sometimes in inverse directions, across disease outcomes and vaccinated populations. We provide examples of how VPDI can be used to reveal the relative public health impact of vaccines in developing countries, which can be masked by focus on VE alone. We recommend that VPDI be incorporated along with VE into the analytic plans of vaccine trials, as well as decisions by funders, ministries of health, and regulatory authorities. © 2014 Elsevier Ltd.

Gessner B.D.,Agence de Medecine Preventive | Shindo N.,Global Influenza Programme | Briand S.,Global Influenza Programme
The Lancet Infectious Diseases | Year: 2011

Acute respiratory infection (ARI) is a leading cause of mortality worldwide, of which influenza is an important cause that can be prevented with vaccination. We did a systematic review of research published from 1980 to 2009 on seasonal influenza epidemiology in sub-Saharan Africa to identify data strengths and weaknesses that might affect policy decisions, to assess the state of knowledge on influenza disease burden, and to ascertain unique features of influenza epidemiology in the region. We assessed 1203 papers, reviewed 104, and included 49 articles. 1-25% of outpatient ARI visits were caused by influenza (11 studies; mean 9·5%; median 10%), whereas 0·6-15·6% of children admitted to hospital for ARI had influenza identified (15 studies; mean 6·6%; median 6·3%). Influenza was highly seasonal in southern Africa. Other data were often absent, particularly direct measurement of influenza incidence rates for all ages, within different patient settings (outpatient, inpatient, community), and for all countries. Data from sub-Saharan Africa are insufficient to allow most countries to prioritise strategies for influenza prevention and control. Key data gaps include incidence and case-fatality ratios for all ages, the contribution of influenza towards admission of adults to hospital for ARI, representative seasonality data, economic burden, and the interaction of influenza with prevalent disorders in Africa, such as malaria, HIV, and malnutrition. © 2011 Elsevier Ltd.

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