5.6 vaccination Flashcards
what is immunity
The ability for an organism to resist infection
What is passive immunity
When antibodies are introduced to individuals from an outside source.
No direct contact with the pathogen or its antigen is necessary to induce immunity, so the immunity is acquired immediately.
The antibodies aren’t produced by the individual themselves so they aren’t replaced when broken down and no memory cells are formed and there is no lasting immunity.
Give two examples of passive immunity
. Anti-venom given to victims of snake bites
. Immunity acquired by the fetus when antibodies pass through the placenta from the mother
What is active immunity
. Produced by stimulating the production of antibodies by the individuals own immune system
Direct contact with the pathogen is necessary
Immunity takes time to develop, but it is long lasting
There are two types of it
There are two types of active immunity, what are they
Natural active immunity
Artificial active immunity
What is natural active immunity
Results from the individual becoming infected with a disease under normal circumstances .
The body produces its own antibodies and may continue to do so for many years
What is artificial active immunity
Forms the basis of vaccination (immunisation)
It involves inducing an immune response in an individual, without them suffering the symptoms of the disease
What is a vaccine
Disease antigens are put into the body by injection or mouth to stimulate an immune response against a particular disease.
The vaccine contains one or more types of antigen from the pathogen, and these antigens stimulate the immune response, and memory cells are produced.
These memory cells remain in the blood and allow a greater, and more immediate response to a future infection with the pathogen.
So as a result there is a rapid production of antibodies, and the new infection is rapidly overcome before it can cause any harm
What is the purpose of a vaccine
It is a precautionary measure to prevent individuals from contracting a disease, it can’t treat individuals who already have the disease
What does the success of a vaccination program depend on
. It must be economically available in sufficient quantities to immunise most of the vulnerable population
. There must be few side effects, if any, from vaccination as unpleasant side effects discourage individuals from being vaccinated
. Means of storing, producing and transporting the vaccine must be available eg hygienic conditions, refrigerated transport and tech advanced equipment
. There must be trained staff with the right skills to give out the vaccine properly at the appropriate time
. It must be possible to vaccinate the vast majority of a vulnerable population to produce herd immunity
What is herd immunity
. This arises when a sufficiently large amount of the population has been vaccinated, so it is difficult for the pathogen to spread among it.
This is because pathogens are spread between people when in close contact, so when the most of the population are immune, it won’t spread so it is unlikely a susceptible individual will come in contact with an infected person
Why is herd immunity important
. It is never possible to vaccinate everyone in a large population
Eg babies, and very young children are not vaccinated because their immune system is not fully functional.
It is dangerous to vaccinate those with compromised immune systems.
Why must vaccination be carried out at one time
Because herd immunity can be achieved so there are very few individuals in the population with the disease at one time so the transmission of the pathogen is interrupted
Why may vaccination not eliminate a disease
6 REASONS
. It fails to induce immunity in certain individuals eg ones with defective immune systems
. If someone develops the disease right after vaccination so their immunity levels aren’t high enough to prevent it, which means they may reinfect others
. Pathogen may mutate so their antigens change suddenly so vaccines can become ineffective against certain strains, as the pathogens aren’t recognised by our immune system so it can’t produce antibodies against it.
Eg influenza
. There are too many varieties of a particular pathogen so its impossible to develop a vaccine against all of them. Eg the cold virus
. Certain pathogens hide from the body’s immune system eg inside cells or living in the intestines out of reach eg cholera
. Individuals may object to vaccination due to religious, ethical or medical reasons. Eg concerns over the MMR vaccine.
Ethical issues of vaccination
7
. Animals are often involved in making vaccines
. Side effects can cause long term harm, how do you know the side effects aren’t worse than the actual disease
. What individuals are tested on for vaccines, how should trials be carried out as there are lots of risks
. Is it fair to trial a vaccine with unknown health risks only in a country where the disease is common.
. Most the population must be vaccinated for it to work but is this fair for it to be compulsory? Should people be forced?
. Should expensive vaccine programmes be continued when a disease is basically eradicated out, if less money is available for the treatment of current diseases
. Vaccinating healthy people to help unhealthy people may make the healthy ones have side effects
