BERLIN (Reuters) - Germany’s IWH economic institute on Thursday cut its 2021 growth forecast for Europe’s largest economy to 3.7% from 4.4% in December as the country risks a third wave of the coronavirus pandemic. “Especially for Germany, there is a danger that the steps decided at the beginning of March to open up (the economy) will trigger a third wave of infection,” the Halle-based institute said. The institute was nonetheless more upbeat about the economy’s prospects this year than the government, which is forecasting 2021 growth of 3%, after a 4.9% slump last year. Germany’s Robert Koch Institute (RKI) has warned of the risk of a third wave of coronavirus infections in Germany.