What is one key characteristic of inactivated vaccines?

Inactivated vaccines are characterized by their inability to replicate because they are made from pathogens that have been killed or inactivated. This means that once these vaccines are produced, the pathogens cannot grow or cause disease, making them safe for immunization. The inactivation process typically involves heat or chemical treatment, which ensures that the antigens are still present to stimulate an immune response without posing a risk of infection.

The other statements do not accurately describe inactivated vaccines. For instance, some vaccines that require replication are live attenuated vaccines, which intentionally use weakened forms of viruses or bacteria that can reproduce in the body. Likewise, inactivated vaccines do not contain live pathogens, as they consist only of the killed components that trigger immune reactions. While it is common for inactivated vaccines to be administered via injection, this is not a defining characteristic, as the method of administration can vary and does not specifically relate to the inactivation process. Thus, the essence of inactivated vaccines lies in their non-replicating nature.