Effects of COVID-19 on paediatric cardiac centres in low-income and middle-income countries: a mixed-methods study oleh Bistra Zheleva, Kimberlee Gauvreau, Kathy Jenkins, Campbell Dopke, Jean Connor, Bojana Bakalcheva, Najeebullah Bina, Gonzalo Calvimontes, Ivana Cerovic, Naizihijwa Majani, Michael Oketcho, Dimitar Pechilkov, Fenny Shidhika, Tengiz Shiryaev