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The impact of reactive mass vaccination campaigns on measles outbreaks in the Katanga region, Democratic Republic of Congo
W. John Edmunds
Sebastian Dietrich
Katiana Rivette
Marit van Lenthe
Isidro Carrion-Martin
Kartini Gadroen
V. Bhargavi Rao
M. Ruby Siddiqui
Saki Takahashi
Sebastian Funk
Joel Hellewell
Novel Coronavirus
Acceso Abierto
The Katanga region in the Democratic Republic of Congo (DRC) has been struck by repeated epidemics of measles. In many of the affected health zones, reactive mass vaccination campaigns were conducted in response to the outbreaks. Here, we attempted to determine how effective campaigns were in curtailing a large outbreak in 2015. Using a model of measles transmission we compared observed case numbers to a counterfactual of no campaigns, by first fitting a model to the data including the campaigns and then re-running this without vaccination. Focusing on eight of the 68 health zones in the Katanga region, we estimated the reactive campaigns to have reduced the size of the outbreaks by approximately 21,000 (IQR: 16,000--27,000; 95% CI: 8300--38,000), or 21% (IQR: 17%--25%, 95% CI: 9.3%--34%) of possible measles cases. There was considerable heterogeneity in the impact of campaigns, with campaigns startgin earlier after the start of an outbreak being more impactful. We further sought to establish whether the spatial pattern of the outbreak could have been determined in advance to help prioritise areas for vaccination campaigns and speed up the response. The best predictors of outbreak size among all the health zones were vaccination coverage derived from cluster surveys and outbreak size in 2010-13. This, combined with the fact that the vast majority of reported cases were in under-5 year olds, would suggest that there are systematic issues of undervaccination. If this was to continue, outbreaks would be expected to continue to occur in the affected health zones at regular intervals, mostly concentrated in under-5 year olds. Taken together, our findings suggest that while a strong routine vaccination regime remains the most effective means of measles control, it might be possible to improve the effectiveness of reactive campaigns by considering predictive factors to trigger a more targeted vaccination response. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement SF was supported by a Wellcome Trust Senior Research Fellowship (210758/Z/18/Z). SF and WJE acknowledge financial support from the Global Challenges Research Fund (GCRF) for the project RECAP, research capacity building and knowledge generation to support preparedness and response to humanitarian crises and epidemics, managed through RCUK and ESRC (ES/P010873/1), from the UK Public Health Rapid Support Team, which is funded by the United Kingdom Department of Health and Social Care, and from the National Institute for Health Research - Health Protection Research Unit for Modelling Methodology. ### Author Declarations All relevant ethical guidelines have been followed and any necessary IRB and/or ethics committee approvals have been obtained. Yes All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived. Not Applicable Any clinical trials involved have been registered with an ICMJE-approved registry such as and the trial ID is included in the manuscript. Not Applicable I have followed all appropriate research reporting guidelines and uploaded the relevant Equator, ICMJE or other checklist(s) as supplementary files, if applicable. Yes All data are available with an R package that can be used to reproduce the results. This is available at
Cold Spring Harbor Laboratory Press
Appears in Collections:Artículos científicos

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