What role can health policy and systems research play in supporting responses to COVID-19 that strengthen socially just health systems? - Gilson, L; Marchal, B; Ayepong, I; Barasa, E; Dossou, J-P; George, A; Guinaran, R; Maceira, D; Molyneux, S; Prashanth, NS; Schneider, H; Shawar, Y; et al. (Oxford University Press, 2020)