How do rabies shots work?

Question

I understand the basics of vaccines and I get the rabies vaccine works, but in the instance where you are attacked by a rabid animal and bitten, how does getting the vaccine immediately help with the development of the disease? Is it not already in your bloodstream?

In: Biology

Answer 1

“Rabies Shots” are generally given as _post-exposure prophylaxis_, often abbreviated as _PEP_. _Post_ means after, and _prophylaxis_ is an action taken to prevent the development of disease.

So after an exposure or possible exposure to rabies, such as a bite from a wild animal known to harbor rabies, we give not one but two types of injections to help prevent the development of rabies.

One of these medicines is a vaccine, given in a series of 4 shots. Vaccines are medicines that train your immune system to be able to fight off an infection. As your post clearly notes, vaccines do not work immediately, and vaccines alone would not be sufficient to prevent rabies

The other medicine is what allows your body to fight off the infection immediately. It is called rabies immune globulin, or rabies Ig.

Immunoglobulins are proteins developed by the immune system. They are shaped like the letter “Y”, and the way that they work is the upper points of the “Y” are shaped to attach to disease-causing substances, and the lower part of the “Y” is like a beacon that tells the rest of the immune system where the problem is, so that it can come get rid of it

We get rabies Ig from the blood of people (or sometimes horses) that have received the rabies vaccine. Their immune systems have the Ig available so that when they are infected with rabies, their bodies can quickly find and neutralize it before they get sick

So we inject people with immune globulin – we try to get at least half of the injection close to the bite or wound to make it work better. This allows the body’s immune system to recognize and neutralize the rabies even though the vaccine has not yet started working. The Ig doesn’t last that long, but by the time it is gone, the vaccine has done its work and the body is producing it’s own Ig to continue to neutralize the rabies.