Social contacts and other risk factors for respiratory infections among internally displaced people in Somaliland

Zandvoort, Kevin van; Bobe, Mohamed Omer; Hassan, Abdirahman Ibrahim; Abdi, Mohamed Ismail; Ahmed, Mohammed Saed; Soleman, Saeed Mohamood; Warsame, Mohamed; Wais, Muna Awil; Diggle, Emma; McGowan, Catherine R; Satzke, Catherine; Mulholland, Kim; Egeh, Mohamed Mohamoud; Hassan, Mukhtar Muhumed; Hergeeye, Mohamed Abdi; Eggo, Rosalind M; Checchi, Francesco

doi:10.1016/j.epidem.2022.100625

Cited by 11 publications

(12 citation statements)

References 24 publications

(34 reference statements)

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“…Residents in Digaale live in overcrowded conditions and likely experience high levels of indoor air pollution. On average, one in five children are malnourished, and residents report a high frequency of direct contacts involving physical touch (12,26,27). While carriage prevalence was high, it is similar to that observed in non-displaced populations in other high-transmission settings in east Africa, and not as high as prevalence observed in rural Gambia where high carriage prevalence is sustained into older adulthood (28–31).…”

Section: Discussionmentioning

confidence: 99%

“…We returned to individual participants two days after the household survey and study enrolment to conduct the contact and risk factor survey, in which we asked about individual-level risk factors including social contacts, and measured anthropometry for children aged 6-59 months. Further details about the design and sampling method, as well as detailed social contact and household-level findings, are described in Van Zandvoort et al (12). In the final week of data collection, one to four weeks after participation in the contact survey, we followed up participants to collect a nasopharyngeal swab sample.…”

Section: Methodsmentioning

confidence: 99%

“…We conducted a cross-sectional survey in October-November 2019. The Digaale IDP camp was established in 2014 and, at the time of our study, housed an estimated population of 3,000 people largely displaced due to drought and food insecurity during 2013 and 2014 (12). The camp is located about 4km south-east of Hargeisa, the capital of Somaliland, and consists of corrugated-steel shelters.…”

Section: Study Population and Sampling Methodsmentioning

confidence: 99%

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Pre-vaccination carriage prevalence ofStreptococcus pneumoniaeserotypes among internally displaced people in Somaliland

van Zandvoort,

Ibrahim Hassan,

Bobe

et al. 2024

Preprint

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Populations affected by humanitarian crises likely experience high burdens of pneumococcal disease. Streptococcus pneumoniae carriage estimates are essential to understand pneumococcal transmission dynamics and the potential impact of pneumococcal conjugate vaccines (PCV). Over 100 million people are forcibly displaced worldwide, yet here we present only the second pneumococcal carriage estimates for a displaced population. In October 2019, we conducted a cross-sectional survey among internally displaced people (IDP) living in Digaale, a permanent IDP camp in Somaliland where PCV has not been implemented. We collected nasopharyngeal swab samples from 453 residents which were assessed for presence of pneumococci and serotyped using DNA microarray. We found that pneumococcal carriage prevalence was 36% (95%CI 31 – 40) in all ages, and 70% (95%CI 64 – 76) in children under 5. The three most common serotypes were vaccine serotypes 6B, 19F, and 23. We estimated that the serotypes included in the 10-valent PNEUMOSIL vaccine were carried by 41% (95%CI 33 – 49) of all pneumococcal carriers and extrapolated that they caused 52% (95%CI 35 – 72) of invasive pneumococcal disease. We found some evidence that pneumococcal carriage was associated with recent respiratory symptoms, the total number of physical contacts made, and with malnutrition in children under 5. Through linking with a nested contact survey we projected that pneumococcal exposure of children under 2 was predominantly due to contact with children aged 2-5 (39%; 95%CI 32 – 48) and 6-14 (25%; 95%CI 18 – 33). These findings suggest considerable potential for direct and indirect protection against pneumococcal disease in Digaale through PCV use in children and potentially adolescents.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Study Population and Sampling Methodsmentioning

confidence: 99%

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Pre-vaccination carriage prevalence ofStreptococcus pneumoniaeserotypes among internally displaced people in Somaliland

van Zandvoort,

Ibrahim Hassan,

Bobe

et al. 2024

Preprint

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“…Population normalised matrices can be calculated from the user normalised matrices with a simple re-scaling as described above. We present these for completeness and the varied utility of each normalisation in different model types in Appendix A, Figures 10,11,12.…”

Section: Contact Matrices In Cox's Bazar Refugee Settlementmentioning

confidence: 99%

“…Surveys of these types have predominantly been run in the Global North, with comparatively few serving countries in which many particularly vulnerable communities reside 10 . Indeed, to date and to our knowledge only one work has published contact matrices for an IDP settlement 11 , and no such work exists on contact matrices in refugee settlements. While such traditional methods of collecting contact data may be considered the gold standard, they are extremely resource consuming to collect, and therefore cannot be run easily during an ongoing outbreak.…”

Section: Introductionmentioning

confidence: 99%

A Mixed-Method Approach to Determining Contact Matrices in the Cox’s Bazar Refugee Settlement

Walker

Aylett-Bullock

Shi

et al. 2022

Preprint

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Contact matrices are an important ingredient in age-structured epidemic models to inform the simulated spread of the disease between sub-groups of the population. These matrices are generally derived using resource-intensive diary-based surveys and few exist in the Global South or tailored to vulnerable populations. In particular, no contact matrices exist for refugee settlements - locations under-served by epidemic models in general. In this paper we present a novel, mixed-method approach, for deriving contact matrices in populations which combines a lightweight, rapidly deployable, survey with an agent-based model of the population informed by census and behavioural data. We use this method to derive the first set of contact matrices for the Cox's Bazar refugee settlement in Bangladesh. The matrices from the refugee settlement show strong banding effects due to different age cut-offs in attendance at certain venues, such as distribution centres and religious sites, as well as the important contribution of the demographic profile of the settlement which was encoded in the model. These can have significant implications to the modelled disease dynamics. To validate our approach, we also apply our method to the population of the UK and compare our derived matrices against well-known contact matrices previously collected using traditional approaches. Overall, our findings demonstrate that our mixed-method approach can address some of the challenges of both the traditional and previously proposed agent-based approaches to deriving contact matrices, and has the potential to be rolled-out in other resource-constrained environments. This work therefore contributes to a broader aim of developing new methods and mechanisms of data collection for modelling disease spread in refugee and IDP settlements and better serving these vulnerable communities.

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Social mixing patterns relevant to infectious diseases spread by close contact in urban Blantyre, Malawi

et al. 2022

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Social contacts and other risk factors for respiratory infections among internally displaced people in Somaliland

Cited by 11 publications

References 24 publications

Pre-vaccination carriage prevalence ofStreptococcus pneumoniaeserotypes among internally displaced people in Somaliland

Pre-vaccination carriage prevalence ofStreptococcus pneumoniaeserotypes among internally displaced people in Somaliland

A Mixed-Method Approach to Determining Contact Matrices in the Cox’s Bazar Refugee Settlement

Social mixing patterns relevant to infectious diseases spread by close contact in urban Blantyre, Malawi

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