Protein-based vaccines use harmless pieces of a virus or bacteria, specifically proteins, to stimulate the immune system. These proteins can be produced in the lab and mimic the structure of the pathogen, helping the body recognize and fight the real infection if it occurs. This type of vaccine does not contain live pathogens, making it safer for individuals, especially those with weakened immune systems. Examples of protein-based vaccines include those developed for diseases like hepatitis B and human papillomavirus (HPV). They are an important tool in preventing infectious diseases and improving public health.