How do vaccines help fight diseases that are caused by bacteria and viruses with capsules or outer coats?

Many vaccines target molecules on a pathogen’s surface, where the immune system can most easily find them. For encapsulated bacteria, the capsule can be a major vaccine target, as seen in conjugate vaccines for pneumococcus and Hib. For viruses, surface proteins or virus-like particles are often used because they are the parts antibodies can neutralize. This surface-targeting strategy is a core idea across many modern vaccines.