An inactivated vaccine is a type of vaccine that uses pathogens, such as viruses or bacteria, that have been killed or inactivated so they can no longer cause disease. This process ensures that the immune system can still recognize the pathogen and mount a defense against it without the risk of infection. Common examples of inactivated vaccines include those for diseases like polio and hepatitis A. These vaccines typically require multiple doses to achieve full immunity, as the inactivated pathogens may not provoke as strong an immune response as live vaccines. Inactivated vaccines are generally considered safe and are suitable for a wide range of individuals, including those with weakened immune systems.