The vaccine develops immunity so when we get the disease the body will already be immune.
Vaccines contain antigens that cause the body to produce memory cells. The body can become immune without showing symptoms.
There are then less people the get the disease from; this is herd immunity
It is better for the vaccine to be injected than taken orally because there are enzymes in the mouth that could break it down.
The antignes on the pathogen activate the primary response. When the body gets infected for a second time you will not get ill.
However some pathogens can change their surface antigens - Antigenic Variation
You can suffer from the disease twice because it will be a different strain of the disease.
Comments
No comments have yet been made