Immunization 101: How do Vaccines Work?

Our little Queen B receiving her second dosage of PCV 13. 

We are all aware that we should vaccinate our children. We know it could protect them against diseases, some of which are deadly. But how do vaccines really protect them?

To understand this, let me talk about our Immune System first. The Immune System is a group of organs, tissues, and cells in our body that can identify foreign agents in our body and kill them. To function properly, it must distinguish correctly the organism’s own healthy cells or tissues from the disease-causing agent.

Immune Response is the process done by our immune system when it detects antigen and produces antibodies to counteract it. Antigen is any substance that triggers the production of antibodies. It can be a part of the virus, bacteria, or any parasitic organism. Meanwhile, an antibody is a substance that will be able to identify a certain antigen and lock on it so it would no longer harm the person.

There are two types of Immune Response: the Primary Immune Response and the Secondary Immune Response. The Primary Immune Response is the initial production of antibodies against antigens. Our immune system will produce several versions of antibodies against a certain antigen. The most effective will predominate until they have locked on all the antigens present. Leucocytes also known as our white blood cells will then destroy the virus, bacteria, or parasitic organism. The amount of the effective antibodies will decrease and will only rise up again when the organism is exposed once more to a similar antigen. This is the Secondary Immune Response.

Our immune system has the wonderful ability to remember the antigens it had destroyed before so the same antibodies will be made again. It is also very specific. Our immune system will produce one type of antibody to neutralize one type of antigen. This is the basis of Immunization.

Immunization is the practice of making a person immune or resistant to a certain infectious disease with the use of a vaccine. A vaccine is a biological preparation that allows us to acquire immunity against a particular disease. It is typically composed of an agent that resembles the disease-causing microorganism or virus like a weakened form of the microbe.

Vaccines can be given through different routes. These are:

• Intramuscular (IM) injection - administers the vaccine into the muscle mass.
• Subcutaneous (SC) injection - administers the vaccine into the subcutaneous layer which is between the muscle mass and the skin.
• Intradermal (ID) injection – administers the vaccine in the top most layer of the skin.
• Oral administration – administers the vaccine as oral drops.
• Intranasal Spay application – administers the vaccine through the nose.

The diagram below shows examples of vaccines and their routes of administration:

This diagram is from the World Health Organization. 

On Part 4 of this blog posts series, I will talk about the BCG and Hepatitis B vaccines which happen to be the first set of vaccines recommended to be given to our babies. 

#xoxo