Using a data-driven search based on aggregate data, we found that euro-area  4  BIS Review 116/2008  transmission did indeed undergo notable changes in the mid-1990s; specifically, there is evidence of a structural break around 1996 and possibly a second one around 1999.
Interestingly, these changes to the monetary transmission process do not seem to have altered the long-run responses of real output and inflation to monetary policy: notably, longrun neutrality still holds, and monetary policy is able to control inflation in the long term. But, maybe surprisingly, monetary transmission in the period 1980-1996 is not significantly different from that in the period 1999-2006.