Vacciantion Flashcards
What is vaccination?
A vaccination is a DELIBERATE EXPOSURE to ANTIGENIC material (vaccine), which ACTIVATES the immune system to make an immune RESPONSE and provide IMMUNITY.
What form does the antigenic material take?
- whole, LIVE microorganism e.g. The smallpox vaccine
- a HARMLESS or ATTENUATED version of the pathogenic organism e.g. Measles and TB vaccine
- a DEAD pathogen e.g. Typhoid and cholera
- a preparation of the ANTIGENS from a pathogen e.g. Hepatitis B vaccine
- some HARMLESS toxin (toxoid) e.g. Tetanus
How is vaccination achieved?
- injection
- orally
How does vaccination work ?
- Injection of antigen or attenuated/weakened/dead pathogen –> immune response
- Antigen/pathogen is engulfed by macrophages and antigens are presented to lymphocytes (macrophages become antigen-presenting cells)
- Particular T-lymphocyte (with complementary antibody) is selected (clonal selection) and divides by mitosis (clonal expansion)
- T-helper cells releases cytokines (interleukins). Interleukins are chemical messengers that can activate and stimulate B-cells.
- Cytokines activate B-lymphocytes and stimulate them to divide and differentiate by mitosis (clonal selection and expansion)
- The B-cells then produce plasma and memory B cells
Plasma cells - secrete antibodies which are complementary to the antigen
Memory B-cells - these are long-lived and remain in circulation and provide IMMUNOLOGICAL memory. Provide secondary response which is FASTER STRONGER than previous immune response to same antigen. Also no symptoms upon reinfection
What is primary response?
When an infected agent is first detected there is delay before the appearance of antibodies in the blood. This is the primary response .
How many days does it take for antibodies to be produced?
It takes about 5 days for antibodies to be produce
Why is there a delay in antibody production?
Because it takes time for the following to occur: - antigen presentation -clonal selection - clonal expansion - differentiation - production of antibodies Also there are no memory cells
What happens in the case of a vaccine once the attenuated vaccine has been dealt with?
In the case of the vaccine once the attenuated vaccine has been dealt with (no symptoms), the number of antibodies in the blood drops rapidly.
However, memory B-cells do remain in the blood and provide IMMUNOLOGICAL MEMORY
Due to the immunological memory what happens upon a second infection by the same pathogen?
Antibody production starts much sooner
Antibody concentration reaches a higher concentration
This is secondary response
How many ways are there to use vaccination to control disease?
- Herd vaccination
2. Ring vaccination
What is herd vaccination?
Herd vaccination is using a VACCINE to provide IMMUNITY to ALL or ALMOST all of the population at risk (80 -85% of population)
Once ENOUGH of the POPULATION are IMMUNE the DISEASE can no longer SPREAD
In the UK there is a vaccination programme to immunise young children against which diseases?
- TB
- DIPHTHERIA
- TETANUS
- WHOOPING COUGH
- POLIO
- MENINGITIS
What is ring vaccination?
Ring vaccination is used when a NEW CASE of disease is reported. It involves vaccinating all the people in the IMMEDIATE VICINITY of the new case(s). E.g. Vaccinating the people in the surrounding house or even whole village or town
What is ring vaccination used for in many parts of the world?
Ring vaccination is used in many parts of the world to control the spread of livestock disease
Give an example of a disease that has almost been eradicated through vaccination?
Diphtheria is a highly contagious bacterial disease that has almost been eradicated through vaccination.