And that's because we actually inject antibodies directly into our blood, into our lymph or into our tissue. And by injecting the antibodies we're not exposing the immune system to our antigens and so we're not giving our immune system the adaptive immunity of our immune system the chance to actually develop those antibodies themselves. So another form of immunity is called passive immunity. In passive immunity, antibodies are developed in the laboratory that are specific to some particular pathogen. And these antibodies, when they're injected into our body they begin to circulate in our blood system, in our lymph system and in our tissue. And if we are exposed to that pathogen that carries that antigen that is complementary to the antibody that was injected into our body in the first place, those antibodies will bind onto those antigens.