• Local discrepancies in measles vaccination opportunities: results of population-based surveys in Sub-Saharan Africa

      Grout, L; Conan, N; Juan Giner, A; Hurtado, N; Fermon, F; N'goran, A; Grellety, E; Minetti, A; Porten, K; Grais, RF (BioMed Central Ltd, 2014)
      The World Health Organization recommends African children receive two doses of measles containing vaccine (MCV) through routine programs or supplemental immunization activities (SIA). Moreover, children have an additional opportunity to receive MCV through outbreak response immunization (ORI) mass campaigns in certain contexts. Here, we present the results of MCV coverage by dose estimated through surveys conducted after outbreak response in diverse settings in Sub-Saharan Africa.
    • Measles in Democratic Republic of Congo: an outbreak description from Katanga, 2010--2011

      Grout, L; Minetti, A; Hurtado, N; François, G; Fermon, F; Chatelain, A; Harczi, G; Ngoie, J; N Goran, A; Luquero, F J; et al. (BioMed Central (Springer Science), 2013-05-22)
      BACKGROUND: The Democratic Republic of Congo experiences regular measles outbreaks. From September 2010, the number of suspected measles cases increased, especially in Katanga province, where Medecins sans Frontieres supported the Ministry of Health in responding to the outbreak by providing free treatment, reinforcing surveillance and implementing non-selective mass vaccination campaigns. Here, we describe the measles outbreak in Katanga province in 2010--2011 and the results of vaccine coverage surveys conducted after the mass campaigns. METHODS: The surveillance system was strengthened in 28 of the 67 health zones of the province and we conducted seven vaccination coverage surveys in 2011. RESULTS: The overall cumulative attack rate was 0.71% and the case fatality ratio was 1.40%.The attack rate was higher in children under 4 and decreased with age. This pattern was consistent across districts and time. The number of cases aged 10 years and older barely increased during the outbreak. CONCLUSIONS: Early investigation of the age distribution of cases is a key to understanding the epidemic, and should guide the vaccination of priority age groups.
    • Measles outbreak response immunization is context-specific: insight from the recent experience of médecins sans frontières.

      Minetti, A; Bopp, C; Fermon, F; François, G; Grais, RF; Grout, L; Hurtado, N; Luquero, F J; Porten, K; Sury, L; et al. (PLoS, 2013-11)
      Andrea Minetti and colleagues compare measles outbreak responses from the Democratic Republic of the Congo and Malawi and argue that outbreak response strategies should be tailored to local measles epidemiology. Please see later in the article for the Editors' Summary.
    • Measles Seroprevalence in Chiradzulu District, Malawi: Implications for Evaluating Vaccine Coverage

      Polonsky, J A; Juan-Giner, A; Hurtado, N; Masiku, C; Kagoli, M; Grais, RF (Elsevier, 2015-07-26)
      Self-reported measles vaccination coverage is frequently used to inform vaccination strategies in resource-poor settings. However, little is known to what extent this is a reliable indicator of underlying seroprotection, information that could provide guidance ensuring the success of measles control and elimination strategies.
    • Reaching Hard-to-Reach Individuals: Nonselective Versus Targeted Outbreak Response Vaccination for Measles

      Minetti, A; Hurtado, N; Grais, RF; Ferrari, M (Oxford University Press, 2013-10-16)
      Current mass vaccination campaigns in measles outbreak response are nonselective with respect to the immune status of individuals. However, the heterogeneity in immunity, due to previous vaccination coverage or infection, may lead to potential bias of such campaigns toward those with previous high access to vaccination and may result in a lower-than-expected effective impact. During the 2010 measles outbreak in Malawi, only 3 of the 8 districts where vaccination occurred achieved a measureable effective campaign impact (i.e., a reduction in measles cases in the targeted age groups greater than that observed in nonvaccinated districts). Simulation models suggest that selective campaigns targeting hard-to-reach individuals are of greater benefit, particularly in highly vaccinated populations, even for low target coverage and with late implementation. However, the choice between targeted and nonselective campaigns should be context specific, achieving a reasonable balance of feasibility, cost, and expected impact. In addition, it is critical to develop operational strategies to identify and target hard-to-reach individuals.
    • Sub-national variation in measles vaccine coverage and outbreak risk: a case study from a 2010 outbreak in Malawi.

      Kundrick, A; Huang, Z; Carran, S; Kagoli, M; Grais, RFF; Hurtado, N; Ferrari, M (BioMed Central, 2019-06-15)
      Background Despite progress towards increasing global vaccination coverage, measles continues to be one of the leading, preventable causes of death among children worldwide. Whether and how to target sub-national areas for vaccination campaigns continues to remain a question. We analyzed three metrics for prioritizing target areas: vaccination coverage, susceptible birth cohort, and the effective reproductive ratio (RE) in the context of the 2010 measles epidemic in Malawi. Methods Using case-based surveillance data from the 2010 measles outbreak in Malawi, we estimated vaccination coverage from the proportion of cases reporting with a history of prior vaccination at the district and health facility catchment scale. Health facility catchments were defined as the set of locations closer to a given health facility than to any other. We combined these estimates with regional birth rates to estimate the size of the annual susceptible birth cohort. We also estimated the effective reproductive ratio, RE, at the health facility polygon scale based on the observed rate of exponential increase of the epidemic. We combined these estimates to identify spatial regions that would be of high priority for supplemental vaccination activities. Results The estimated vaccination coverage across all districts was 84%, but ranged from 61 to 99%. We found that 8 districts and 354 health facility catchments had estimated vaccination coverage below 80%. Areas that had highest birth cohort size were frequently large urban centers that had high vaccination coverage. The estimated RE ranged between 1 and 2.56. The ranking of districts and health facility catchments as priority areas varied depending on the measure used. Conclusions Each metric for prioritization may result in discrete target areas for vaccination campaigns; thus, there are tradeoffs to choosing one metric over another. However, in some cases, certain areas may be prioritized by all three metrics. These areas should be treated with particular concern. Furthermore, the spatial scale at which each metric is calculated impacts the resulting prioritization and should also be considered when prioritizing areas for vaccination campaigns. These methods may be used to allocate effort for prophylactic campaigns or to prioritize response for outbreak response vaccination.