LONDON, Nov 30 (Reuters) - Bank of England interest-rate setter Silvana Tenreyo said news about the development of COVID-19 vaccines was very positive but the biggest impact on the economy would only come when vaccine programmes were actually rolled out. Tenreyro said the progress on creating jabs to counter coronavirus would reduce one of the bigger downside risks to BoE’s medium-term economic forecasts and households might delay spending until vaccines have reduced health risks. (Reporting by David Milliken Writing by William Schomberg)