So I understand the need for rabies vaccination "before" exposure since the vaccine basically prepares the immune system, so that in the future should the same intruder enter the body again, the immune system already knows how to handle it.

What I dont understand however is the need of an immediate rabies vaccine for a person after he/she has been exposed to rabies virus (bitten, scratched by a rabid dog) , assuming he/she has not been vaccinated before.

The rabies virus is already in the saliva of the rabid animal right? and the immune system should already start making the necessary antibodies to counter it right? What's the purpose of injecting a weaker version of the virus if the immune system is going to create the antibodies anyway?

Is the immune system more effective, efficient and quick in creating a solution if it is introduced to a much weaker version of the virus? And after figuring out a "fix", it applies this to the original, strong version of the virus?

Or is the immune system not very responsive to the original virus and it must be "triggered" first to create the necessary "fix" by introducing a weaker version with which it is more responsive?

In any case, I'm quite lost on this.

  • 2
    The vaccine help the immune system to develop a quicker response to the threat. If not you can die before your immune system figured out how to fight the virus
    – holyknight
    Commented Mar 17, 2017 at 1:50
  • @holyknight but after the bite, you already have the live virus in your body. What is the advantage of adding more virus (dead or alive) through vaccine? Why would the virus from the vaccine help immune system to develop a quicker response as compared to the virus from the bite?
    – user93353
    Commented Oct 7, 2023 at 3:24

1 Answer 1


It is because rabies take time to kill you and vaccine that you are given is 'dead' virus so it makes it easy to develop antibodies against and when you have antibodies you can fight actual virus

  • But you already have a live virus inside your body because of the dog bit. That should make it easy for your immune system to create antibodies. What advantage does it give to also add dead virus? Shouldn't immunoglobulin be enough as treatment?
    – user93353
    Commented Oct 7, 2023 at 3:22
  • @user93353 the real virus works in such a way your immune system can't handle. Here's a good YouTube on it youtube.com/… Commented Oct 7, 2023 at 8:09
  • I know that the real virus is more dangerous. However, it's already inside the body of someone who has been infected. So what's the point of adding an inactivated virus into the picture.
    – user93353
    Commented Oct 7, 2023 at 8:12
  • Cause your body can handle the inactivated virus and make antibodies before you die from the real thing? :) I must be missing something. Commented Oct 7, 2023 at 10:53
  • But if the real thing is already inside you, then why is the body not making antibodies already? Does the body make antibody faster with inactivated than with real virus? Else this makes no sense
    – user93353
    Commented Oct 7, 2023 at 10:56

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