The impact of COVID-19 control measures on social contacts and transmission in Kenyan informal settlements Dahkki Quaife, M, van Zandvoort, K, Gimma, A, Shah, K, McCreesh, N, Prem, K, Barasa, E, Mwanga, D, Kangwana, B, Pinchoff, J, CMMID COVID-19 Working Group, Edmunds, WJ, Jarvis, CI, Austrian, K