Question

The immune system is in the forefront of the news today because of the coronavirus. You body's immune system has two ways to create immunity, through innate or acquired immunity. Please explain select any vaccine you may you mau have receive and explain what exactly was done to you and are you sure it worked.

i.e I was vaccinated with the chickenpox virus but when I went to Senior High School and yet I gor the chickenpox. why did i get the disease if i was vaccinated.

i.e I was vaccinated for the teranis virus when I was akid playing in my yard and got scratched by a dirty nail. Just recently I cut myself again, and I was told I needed to get it again. They call it a Booster. Why? and if that is true does that mean I need another polio virus vaccine( booster)??

Explain in at least 250 words of content

Answer 1

IMMUNE SYSTEM - Introduction

Immune system consists of two components - Innate immunity and Adaptive immunity.

Innate immunity is body's first level of defence against an organism and includes physical barriers like skin, lysozyme in tears, dendritic cells, natural killer cells, components of the complement system, natural killer cells, phagocytic cells like macrophages, neutroplils etc.

Adaptive immunity is the second line of defence against an organism. It shows a delayed response than the innate immunity and is specific against a particular pathogen. Adaptive immunity includes two main divisions - Cell mediated immunity and Humoral immunity.  Destruction of the pathogen infected cells with the help of cytotoxic T lymphocytes is called cell mediated immunity and the destruction of the extracellular pathogen by forming antibodies against them with the help of B lymphocytes is called humoral immunity.

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How vaccines work ???

At vaccination, we are introducing live attenuated organism / killed organisms / inactivated toxins / some components of the organisms by oral or parenteral route.

This vaccine antigen attracts local and systemic dentritic cells, monocytes and neutrophils

Activation of these cells occurs which migrate along the lymphatic vessels to the draining lymph nodes.

This leads to antigen presentation to B and T - lymphocytes leading to their activation. The B lymphocytes proliferate into plasma cells which produces antibodies - Primary immune response

Some B cells undergo germinal centre reaction to form the memory B cells.

When there is a second exposure to the same antigen / a booster dose, reactivation of these memory B cells occurs leadingto a rapid increase in the antibody levels - Secondary immune response

So, when a vaccinated person comes into contact with that particular pathogen, a secondary immune response is generated leading to rapid production of antibodies so that the organism is eliminated from the body.

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What is the need for boosters ? Do all vaccines need boosters ?

Usually the production of protective antibodies by the memory B cells by secondary immune response takes 4 - 7 days.

Diseases with incubation period shorter than this period - diphtheria, tetanus, chicken pox etc. need regular boosters to maintain a protective antibody levels.

Whereas diseases with long incubation period - hepatitis A, hepatitis B do not need regular boosters. Because, during this incubation period (>7 days), the memory B cells can produce adequate protective antibodies.

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I was vaccinated with the chickenpox virus but when I went to Senior High School and yet I gor the chickenpox. why did i get the disease if i was vaccinated ?

Here, the protective antibody levels wean off with age, but memory B cells are produced during vaccination. These memory B cells are to be reactivated with regular boosters to maintain protective antibody levels. Here, in this case, the person got the disease since the booster dose was not received.