Vulnerability of Syrian refugees in Lebanon to COVID-19: quantitative insights.

Lebanon, a middle-income country with ongoing political turmoil, unstable economic situation, and a fragmented and under-resourced health system, hosts about one million Syrian refugees since 2011. While the country is currently experiencing substantial COVID-19 epidemic spread, no outbreaks have been reported yet among Syrian refugees. However, testing of this population remains limited and exposure levels are high given dire living conditions and close interaction with the host community. Here, we use quantitative insights of transmission dynamics to outline risk and contextual factors that may modulate vulnerability of Syrian refugees in Lebanon to potentially large COVID-19 epidemics.Syrian refugees live in close contact with the host community, and their living conditions are favorable for epidemic spread. We found that the high levels of crowding within Syrian refugee households and among those in informal tented settlements, the inadequate water supply and sanitation, limited use of masks, inadequate access to health care, and inadequate community awareness levels are vulnerability factors that directly impact important parameters of transmission dynamics, leading to larger epidemic scale. Poverty, stigma, and fear of legal consequences are contextual factors that further exacerbate this vulnerability. The relatively high prevalence of non-communicable diseases in this population could also affect the severity of the disease among those infected. Mathematical modeling simulations we conducted illustrated that even modest increases in transmission among Syrian refugees could result in a large increase in the incidence and cumulative total number of infections in the absence of interventions.In conclusion, while the young age structure of the Syrian refugee population might play a protective role against the scale and disease-burden severity of a potential COVID-19 epidemic, the epidemic potential due to several vulnerability factors warrants an immediate response in this population group. Local and international actors are required to mobilize and coordinate efforts to prevent the transmission of COVID-19, and to mitigate its impact amongst the vulnerable refugee populations globally.