We know they come around every year: flu season and flu shots. But, what does it take to prepare the flu vaccine each year to be sure it’s safe and effective? Nicola Klein, MD, PhD, is director of the Kaiser Permanente Vaccine Study Center, in Oakland, Calif. We sat down with her to better understand what the center does and get answers to questions such as: Who should get the flu vaccine each year? Does the vaccine lose effectiveness? What else should we know about the research and what it’s shown?