From Ars Technica: Vaccines are one of the most successful public health interventions we’ve developed—a simple injection can lead to a life-long immunity to disease-causing agents. But not every vaccine is so successful; for a number of agents, regular booster shots are needed to prevent immunity from fading. But researchers are starting to look into a possible route around this problem: a self-boosting vaccine. The challenge will be making one that’s safe and acceptable to the public.