On this edition of KCBS In Depth, we take a closer look at the science of the immune system to help understand why viral infections like flu and RSV are surging this year after two relatively mild winter seasons. Guests:  Dr. Michael Rose, physician specializing in internal medicine and pediatrics, Johns Hopkins University School of Medicine Dr. Keren Landman, senior reporter covering public health and infectious diseases, Vox  Host: Keith Menconi