WASHINGTON (Reuters) - U.S. consumer confidence unexpectedly weakened in September as soaring COVID-19 infections deepened concerns about the economy’s near-term prospects. The Conference Board said on Tuesday its consumer confidence index dropped to a reading of 109.3 this month from 115.2 in August. That was the third straight decline and the lowest level since February. Economists polled by Reuters had forecast the index nudging up to 114.5. Reporting by Lucia Mutikani; Editing by Chizu Nomiyama Our Standards: The Thomson Reuters Trust Principles.