191. African swine fever virus (ASFv) is endemic in wild boar in Eastern Europe, challenging 20 elimination in domestic swine. Estimates of the distances between transmission events 21 are crucial for predicting rates of disease spread to guide allocation of surveillance and 22 23 processes in hosts, but effects of these processes on spread are poorly understood, and 24 inferences often include only one process. 25 2. To understand effects of spatial and social processes on disease dynamics we developed 26 spatially-explicit transmission models with different assumptions about social and/or 27 spatial contact processes. We fit the models to ASFv surveillance data from Eastern 28 Poland from 2014-2015 and evaluated how inclusion of social structure affected 29 inference. 30 3. The model that accounted for social along with spatial processes provided better 31 inference of spatial spread and predicted that ~80% of transmission events are within the 32 same family group. 33 4. The models predicted dramatically different effective reproductive numbers, both in 34 magnitude and variation. 35 5. Specifying contact structure with spatial but not social processes can lead to very 36 different disease dynamics and inference of epidemiological parameters. Uncertainty in 37 these processes should be accounted for in predicting spatial spread in social species. 38 39 KEYWORDS: African swine fever, Effective reproduction number, Spatial transmission kernel, 40 Surveillance, Wild boar, 41 42 45 3 disease spread per transmission event and inform how surveillance, containment, or mitigation 46 strategies should be deployed [1]. For example, information on where cases may arise can inform 47 what spatial radius should be used for ring culling, ring vaccination, spatial quarantine or 48 intensive surveillance [2]. Without detailed genetic data or contact tracing data to reconstruct 49 transmission history, STKs are predominantly estimated indirectly by fitting disease transmission 50 models to available case data [1-3] providing valuable insight for developing intervention 51 strategies [4-7]. However, models often make simplifying assumptions based on the available 52 information that could have negative impacts on policy decisions if the models are not robust to 53 violation of these assumptions. Common assumptions in models for estimating STKs include 54 assuming a single introduction event and assuming observation of all transmission events [8]. 55Methods that account for these processes are important for providing more realistic predictions 56 of spatial spread in systems where these assumptions are violated. 57 Another common issue is that the potential scope of contact heterogeneities is often 58 simplified or lacking, such that uncertainty in model specification cannot be considered despite 59 its potential importance [9]. In non-vector-borne disease systems, key drivers of contact 60 heterogeneities include social [10] and spatial processes [2], yet our understanding of the relative 61 role of these processes in ...