How can I asses the impact of intervention overtime(particularly PCV10), We had analysed effect PCV10 in population and found out that it has a postive impact(It reduced incidences of pneumonia) .We analysed the data from 2002 to 2015. Now that I we want the analysis upto 2019, were are interested in vaccine impact over time rather than just its effectiveness( Is the impact increasing or decerasing overtime or constant overt time).How ca I Show this statistically