• Time is (still) of the essence: quantifying the impact of emergency meningitis vaccination response in Katsina State, Nigeria.

      Ferrari, M J; Fermon, F; Nackers, F; Llosa, A; Magone, C; Grais, RF (Oxford University Press, 2014-09-05)
      In 2009, a large meningitis A epidemic affected a broad region of northern Nigeria and southern Niger, resulting in more than 75 000 cases and 4000 deaths. In collaboration with state and federal agencies, Médecins Sans Frontières (MSF) intervened with a large-scale vaccination campaign using polysaccharide vaccine. Here the authors analyze the impact (cases averted) of the vaccination response as a function of the timing and coverage achieved.
    • Time is of the essence: exploring a measles outbreak response vaccination in Niamey, Niger.

      Grais, RF; Conlan, A J K; Ferrari, M J; Djibo, A; Le Menach, A; Bjørnstad, O N; Grenfell, B T; Epicentre, 8 rue Saint Sabin, 75011 Paris, France. rebecca.grais@epicentre.msf.org (The Royal Society Publishing, 2008-01-06)
      The current World Health Organization recommendations for response during measles epidemics focus on case management rather than outbreak response vaccination (ORV) campaigns, which may occur too late to impact morbidity and mortality and have a high cost per case prevented. Here, we explore the potential impact of an ORV campaign conducted during the 2003-2004 measles epidemic in Niamey, Niger. We measured the impact of this intervention and also the potential impact of alternative strategies. Using a unique geographical, epidemiologic and demographic dataset collected during the epidemic, we developed an individual-based simulation model. We estimate that a median of 7.6% [4.9-8.9] of cases were potentially averted as a result of the outbreak response, which vaccinated approximately 57% (84563 of an estimated 148600) of children in the target age range (6-59 months), 23 weeks after the epidemic started. We found that intervening early (up to 60 days after the start of the epidemic) and expanding the age range to all children aged 6 months to 15 years may lead to a much larger (up to 90%) reduction in the number of cases in a West African urban setting like Niamey. Our results suggest that intervening earlier even with lower target coverage (approx. 60%), but a wider age range, may be more effective than intervening later with high coverage (more than 90%) in similar settings. This has important implications for the implementation of reactive vaccination interventions as they can be highly effective if the response is fast with respect to the spread of the epidemic.
    • Urban Cholera transmission hotspots and their implications for Reactive Vaccination: evidence from Bissau city, Guinea Bissau

      Azman, A S; Luquero, F J; Rodrigues, A; Palma, P P; Grais, RF; Banga, C N; Grenfell, B T; Lessler, J; Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America. (2012-11-08)
      Use of cholera vaccines in response to epidemics (reactive vaccination) may provide an effective supplement to traditional control measures. In Haiti, reactive vaccination was considered but, until recently, rejected in part due to limited global supply of vaccine. Using Bissau City, Guinea-Bissau as a case study, we explore neighborhood-level transmission dynamics to understand if, with limited vaccine and likely delays, reactive vaccination can significantly change the course of a cholera epidemic.
    • Use of Lot Quality Assurance Sampling (LQAS) to estimate vaccination coverage helps guide future vaccination efforts.

      Alberti, K; Guthmann, J P; Fermon, F; Nargaye, K D; Grais, RF; Epicentre, 8 rue Saint Sabin, 75011 Paris, France. kalberti@epicentre.msf.org (Elsevier, 2008-03)
      Inadequate evaluation of vaccine coverage after mass vaccination campaigns, such as used in national measles control programmes, can lead to inappropriate public health responses. Overestimation of vaccination coverage may leave populations at risk, whilst underestimation can lead to unnecessary catch-up campaigns. The problem is more complex in large urban areas where vaccination coverage may be heterogeneous and the programme may have to be fine-tuned at the level of geographic subunits. Lack of accurate population figures in many contexts further complicates accurate vaccination coverage estimates. During the evaluation of a mass vaccination campaign carried out in N'Djamena, the capital of Chad, Lot Quality Assurance Sampling was used to estimate vaccination coverage. Using this method, vaccination coverage could be evaluated within smaller geographic areas of the city as well as for the entire city. Despite the lack of accurate population data by neighbourhood, the results of the survey showed heterogeneity of vaccination coverage within the city. These differences would not have been identified using a more traditional method. The results can be used to target areas of low vaccination coverage during follow-up vaccination activities.
    • Use of Vibrio cholerae Vaccine in an Outbreak in Guinea

      Luquero, F J; Grout, L; Ciglenecki, I; Sakoba, K; Traore, B; Heile, M; Diallo, A A; Itama, C; Page, A-L; Quilici, M-L; et al. (Massachusetts Medical Society, 2014-05-29)
    • Vaccination in humanitarian crises: satisficing should no longer suffice

      Grais, RF; Juan-Giner, A (Oxford University Press, 2014-08-04)
      There are more possible vaccination interventions to mitigate the adverse health consequences of populations in crises than ever before, but recent reviews suggest delivering these vaccines has been fraught with difficulty. The decision to implement vaccination interventions in crises remains, more often than not, an exercise in satisficing. The sparse credible epidemiologic and effectiveness data in populations affected by crises contributes greatly to decision-making difficulty, as do the limits of vaccine presentations, formulations and storage. Political considerations and lack of decision-making guidance contribute further. Moving forward requires sound effectiveness studies to help ensure that decision-making is based to the degree possible on substance.
    • The value of and challenges for cholera vaccines in Africa.

      von Seidlein, L; Jiddawi, M; Grais, RF; Luquero, F J; Lucas, M; Deen, J; Menzies School of Health Research, Casuarina, Australia. (2013-11)
      The 21st century saw a shift in the cholera burden from Asia to Africa. The risk factors for cholera outbreaks in Africa are incompletely understood, and the traditional emphasis on providing safe drinking water and improving sanitation and hygiene has proven remarkably insufficient to contain outbreaks. Current killed whole-cell oral cholera vaccines (OCVs) are safe and guarantee a high level of protection for several years. OCVs have been licensed for >20 years, but their potential for preventing and control cholera outbreaks in Africa has not been realized. Although each item in the long list of technical reasons why cholera vaccination campaigns have been deferred is plausible, we believe that the biggest barrier is that populations affected by cholera outbreaks are underprivileged and lack a strong political voice. The evaluation and use of OCVs as a tool for cholera control will require a new, more compassionate, less risk-averse generation of decision makers.