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.
Other than the direct effects on health or reducing the number of deaths, the government spends a large amount of money on immunisation, why?
- days lost at work effect the economy
- costs more to deal with ill people than the vaccination cost
- response to public opinion
- if everyone was ill health service wouldn’t be able to cope
Who should get vaccinated and why?
Elderly and children - they have weak immune systems/ never dealt with the pathogen before
Pregnant women - foetus/embryo has undeveloped immune system
Health workers - likely to be at increased risk of disease
Those with chronic disease- inability to withstand further disease/ already in poor health
Patients with HIV/AIDS/TRANSPLANT/CHEMOTHERAPY - weak immune system/cannot produce many antibodies
What can happen to a routine vaccination programme once a disease has been eradicated or reduced to such a low incidence that it is unlikely to spread?
Once a disease has been eradicated, or reduced to such a low incidence that it is unlikely to spread, the routine vaccination programme can be relaxed e.g. Small pox
What are some pathogens able to do and how does this impact memory cells?
Some pathogens can undergo genetic mutations which change their antigens
This means memory cells produced by vaccination may not recognise the new antigens
Give an example of a virus which often undergoes changes in its antigen resulting in epidemics?
Influenza
What happened during the 1918 flu epidemic?
The 1918 flu epidemic killed at least 40 million people world wide
Some estimates are as high as 100 mill
Define epidemic?
Epidemic means the RAPID spread of a disease through a HIGH proportion of the POPULATION
What is a pandemic?
A worldwide epidemic
Give an example of an immunisation scheme which vaccinantes people at risk in order to prevent a pandemic?
In the uk there is a vaccination programme to immunise everyone over 65yo to help prevent them from being made ill from the influenza virus.
The strains of flu used in the immunisation change each year
What are the problems associated with vaccination?
- Antigenic variation
2. Some people dont get immunised
Why are new strains of the influenza virus constantly emerging?
New strains of the influenza virus are constantly emerging, because antigens displayed on the virus change due to mutation. This causes antigenic variation
What happens when a new strain of flu virus arises that is particularly virulent?
Occasionally a new strain of flu virus arises that is particularly virulent, this might cause an epidemic
What do scientists try to do to combat antigenic variation?
Scientists try to predict what the next antigen will be
Why do some people not get immunised?
- Being too busy/cba
- lack of trust in government
- media scare stories e.g. MMR
- concerned about side effects
- cost implications to individuals
- allergic to vaccine
- fear of needles
- religious/cultural/e this all reasons
Define active immunity?
Active immunity = immunity achieved by the activation of the immune system
What happens in active immunity?
Lymphocytes manufacture antibodies and release them into the blood
Memory cells remain behind meaning this type of immunity can last many years or even a life time
What is NATURAL ACTIVE IMMUNITY?
Immunity provided by antibodies made in the immune system as a result of infection
E.g. Person suffers from disease and then becomes immune
What is ARTIFICIAL ACTIVE IMMUNITY?
Deliberate exposure to antibody/antigen
Immunity provided by antibodies as a result of vaccination
What is passive immunity?
Passive immunity = This is the immunity achieved by antibodies that have NOT been MANUFACTURED by STIMULATING the recipients immune system.
What is NATURAL PASSIVE IMMUNITY?
Normal course of living processes;
Antibodies provided via PLACENTA or BREAST milk
Makes baby immune to disease
Important in first year of babys life when immune system is developing
What is ARTIFICIAL PASSIVE IMMUNITY?
Antibodies provided by injection of antibodies made BY ANOTHER INDIVIDUAL e.g. Tetanus injections
What is antivenom?
Antivenom is produced by injecting small amounts of venom into another animal e.g. Pig and then extracting the antibodies from it’s blood. The antibodies are then injected to the person who has been bit - artificial passive immunity
