vaccination Flashcards
(12 cards)
what is immunity?
the ability of an organism to resist infection
in simple terms, what is meant by active immunity?
antibodies are produced by a person’s own plasma B cells
in simple terms, what is meant by passive immunity?
antibodies are passed onto the person, and these have not been created by the person’s own plasma B cells
compare active and passive immunity?
-active involves memory cells, passive does not
-active involves production of antibody by body’s own plasma B cells, passive involves antibody introduced from outside (no direct contact with antigen necessary)
-active long term because the antibody is produced in response to antigen, passive short term because antibody is broken down
-active can take time to develop/ work whereas passive is fast acting
what is meant by vaccination?
the introduction of the appropriate disease antigens into the body
what do vaccines contain?
antigens, which are usually on dead or attenuated (weakened) pathogens
what are the criteria for a successful vaccination?
-economical in sufficient quantities
-available to most- herd immunity
-few side effects
-be able to be produced, stored and transported
- be able to be administered at appropriate times, which involves training staff with appropriate skills at different centres throughout pop
what is meant by herd immunity?
when a significantly large proportion of the population has vaccinated to make it difficult for a pathogen to spread within that population (so even non-immune people are protected from disease)
what are the reasons why a vaccination may not eliminate a disease?
-vaccinations can fail to induce immunity in certain individuals e.g. people with defective immune systems
-individuals may develop the disease before the vaccination boosts the immune system
-may be too many strains of a pathogen to vaccinate against all
-certain pathogens are harder to locate in immune system e.g. viruses because they replicate inside cells
-people may object to vaccinations for personal reasons
-pathogen may mutate quickly or frequently- antigenic variability
what is meant by antigenic variability?
on some pathogens, the surface antigens can change (due to random mutations)
what is the problem with antigenic variability?
when you are infected for the second time, the memory cells won’t recognise the new antigens so the secondary response won’t be activated
we have to start over from scratch with a new primary immune response
this also makes it more difficult to develop vaccines
what are some ethical considerations of using vaccines?
-use of animals- acceptable?
-side effects can cause long-term harm, how can risk of side effects be balanced against risk of disease that causes greater harm?
-who should vaccines be tested? how should trials be carried out?
-is it acceptable to trial a new vaccine with unknown health risks, only in a country where the targeted disease is common?
-should vaccines be compulsory to make it most effective? is this all the time or just if there is a potential epidemic?
-should expensive vaccination problems continue when a disease is almost wiped out, if this means less money for treatment of other diseases?
-how can individual health risks from vaccination be balanced against advantages of controlling disease for large pop?
