Biology · Human Health and Diseases · NEET
Antivenom contains ready-made (preformed) antibodies against the snake venom. It does NOT contain antigen. The antibodies are made outside the body and then injected in. Because the antibodies are given directly, the patient's own immune system does not have to work. This is why NEET calls antivenom a source of passive immunity.
Antivenom gives passive immunity. In passive immunity, ready-made antibodies are given directly to the body. Active immunity is different: there the body is exposed to an antigen and makes its own antibodies. Since antivenom hands over the finished antibodies, no antigen is involved and no memory cells form.
A vaccine contains an antigen. This can be a weakened (attenuated) pathogen, an inactivated/dead pathogen, or antigenic proteins of the pathogen. Oral polio drops contain attenuated (weakened) pathogens. The body reacts to this antigen and produces its own antibodies and memory cells, so this is active immunity.
Snake venom acts very fast, so there is no time for the body to make its own antibodies. A vaccine (active immunity) is slow and takes days to give full protection. So we inject preformed antibodies (antivenom) that neutralise the venom immediately. NCERT gives the same reason for tetanus: quick response is needed, so preformed antibodies (antitoxin) are injected.
Because the body did not make these antibodies and did not form memory cells. The injected antibodies are slowly broken down and removed. So protection is short-lived. A vaccine lasts longer because it creates memory cells that respond fast on the next exposure.
Antivenom injection contains preformed antibodies while polio drops that are administered into the body contain:
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Both work the same way: they are preparations of preformed antibodies. Antitoxin is used against a toxin (for example in tetanus), and antivenom is used against snake venom. Both give passive immunity because the antibodies are ready-made and injected directly.
No. Antivenom only supplies finished antibodies. No antigen enters the body, so no memory cells are formed. That is why passive immunity is fast but does not last and gives no long-term protection.
Colostrum (mother's first milk, rich in IgA antibodies) gives passive immunity, just like antivenom, because the baby receives ready-made antibodies instead of making its own. Antibodies passed from mother to foetus are also passive immunity.
Antivenom is faster because the antibodies are already made and act at once. A vaccine (active immunity) is slow and takes time to give full protection because the body must first make its own antibodies.
