BERLIN, Jan 25 (Reuters) - Germany faces huge fiscal challenges following the COVID-19 pandemic and won’t be able to stick to its strict debt limits for years, Chancellor Angela Merkel’s chief of staff was quoted as saying on Monday. “The debt brake cannot be adhered to in the coming years even with otherwise strict spending discipline”, Helge Braun wrote in an op-ed piece for business daily Handelsblatt to be published in its Tuesday edition. (Reporting by Michael Nienaber, Editing by Edward Taylor)