CBSE Class 9 Answered

Artificially acquired active immunity occurs through the injection of the causative agent into the person’s system. This process is called vaccination, inoculation or immunization and the substance injected is called a vaccine. The causative agent is diluted to reduce its virulence so that the recipient will form antibodies without any effect on the body.

Tetanus is an example of immunization that can either be active or passive. The active form is given as a tetanus booster and causes the person to form his or her own antibodies against tetanus. Tetanus can also be given in the passive form if the person has become ill due to infection by tetanus.