European Central Bank (ECB) President Mario Draghi speaks during the IMFS Conference 2015 of the Institute for Monetary and Financial Stability in Frankfurt March 11, 2015. European Central Bank buying of government and other debt may be shielding countries in the euro zone from any knock-on effect from events in Greece, ECB President Mario Draghi said on Wednesday. REUTERS/Ralph Orlowski (GERMANY - Tags: BUSINESS HEADSHOT)