" We 're optimistic we can deliver the vaccine to these people in time to do good , " said Dr. David Fleming , the CDC 's deputy director for Public Health and Science .
" We 're optimistic we can deliver the vaccine to these people in time to do good , " said Dr. David Fleming of the Centers for Disease Control and Prevention .
seek to identify programs net impacts that can be attributed to the program over and above the effects of usual care strong experimental or quasi-experimental design