WASHINGTON (Reuters) - Both private and public sector initiatives are needed to help the world's poorest countries grapple with debt challenges exacerbated by the coronavirus pandemic, the Institute of International Finance said on Thursday.IIF signaled its support for a push by the World Bank and International Monetary Fund for official bilateral creditors to suspend debt payments for the poorest countries in a letter to the World Bank, IMF, OECD and Paris Club creditors.The letter from the..