An anonymous reader writes: Vaccines, contrary to opinions from the anti-science crowd, are some of the most effective tools in modern medicine. For some diseases, a single shot is all it takes for lifetime immunity. Others, though, require booster shots, to remind your immune system exactly what it should prepare to fight. Failure to get these shots threatens an individual's health, and the herd immunity concept as well. Scientists are now looking into 'self-boosting' vaccines in order to fix that problem. Some viruses are capable of remaining in the human body for a person's entire lifetime. If researchers can figure out a way to safely harness these, it may be possible to add genes that would create proteins to train the immune system against not just one, but multiple other viruses (abstract). This is a difficult problem to solve; changing the way we do vaccinations will itself have consequences for herd immunity. It also hinges on finding a virus that can survive the immune system without have uncomfortable flare-ups from time to time.