Vaccination

Vaccination

Immunity
1. Passive
  1. Introduction of antibodies into individuals from an outside source
  2. Antibodies aren't produced by the individual, so they aren't replaced when broken down
    1. Short lived immunity
2. Active
  1. Stimulating the production of antibodies by the individuals own immune system
  2. Can provide herd immunity
Successful vaccination programme
1. Suitable vaccine must be economically available in sufficient quantities to immunise all of the vunerable population
2. Few side effects to encourage individuals to get vaccinated
3. Producing, storing and transporting must be available
4. Must be a way to administer properly, so training staff
5. Must be possible to vaccinate the vast majority of the vulnerable population
Why does vaccination not eliminate a disease?
1. Fails to induce immunity in certain individuals
2. Disease may develop immidiately after vaccination, but before immunity levels are high enough for prevention
3. May be mutations
  1. New antigens change suddenlym meaning that the antigens are no longer recognised
  2. This is antigenic variability
4. Lots of varieties of a particular pathogen
5. Pathogens can hide from the immune system
  1. Conceal themselves inside of living cells
  2. Living in places out of reach
6. People may have objections to vaccinations
Problems with control of cholera
1. Intestinal, so not easy to reach
2. Oral treatment rarekly has time to be effective as it is rapidly flushed from the intestines
3. Antigenic variability
4. Mobile populations make it difficult to ensure individuals are vaccinated
Problems with control of TB
1. Increase in HIV meaning more impaired immune systems
2. Refugees move and are housed in overcrowded places
3. Mobile populations make it difficult to vaccinate everyone
4. Aging population with less effective immune systems
MMR Vaccine
1. 1988, combined vaccine for mumps, measles and rubella
2. 10 years later a well respected medical journal published a study suggesting there was a higher incidence of autism amongst children who recieved the MMR
3. Many parents decided to have individual vaccinations, or not have their children vaccinated at all
4. Incidence of mumps, measles and rubella rose
5. Since the report was published, it has been found
  1. Author had a confict of interests
    1. Was being paid by the Legal Aid Board to discover whether parents who claimed their children had been damaged by MMR had a case
  2. Further studies have found no link
  3. Sample size was small
  4. The journal that published the initial research has publicly declared that, had it known all the facts, it would not have published the work
6. Theories must be initially treated with caution
  1. Must be peer reviewed
  2. Scientists may have vested interests
  3. Personal beliefs, views and opinions may influence the way they approach or represent their research
  4. Facts presented may have been biased or distorted to suit the presenters interests
  5. New knowledge may challenge scientific beliefs
Ethics of vaccination
1. Often involves use of animals
2. Side effects which may cause long-term harm
3. Who should vaccines be tested on and how should such trials be carried out
4. Is it acceptable to trial a new vaccine with unknown risks only in a country where the targeted disease is common on the basis that there is the most to gain?
5. Most if not all of the population should be vaccinated - is it fair for vaccination to be compulsary?
6. Should expensive vaccinations continue even when the disease has almost been eradicated if it means less money for the treatment of other diseases
7. How can individual health risks from vaccination be balenced against the advantages of controlling a disease for the benefit of the population at large?

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	Criado por Beth Ritchie quase 11 anos atrás