So you took organisms and you got an immune response, and sometimes those organisms, even though they were dead, gave you a pretty whopping immune response: your arms were sore, you got fevers.
Pues, se tomaban organismos y se creaba una respuesta inmune y algunas veces esos organismos, aunque ya estaban muertos, daban una respuesta inmune potente: dolores en los brazos y fiebre.