Vaccination

Vaccination

1. Immunity

   • Passive
     • Introduction of antibodies into individuals from an outside source
     • Antibodies aren't produced by the individual, so they aren't replaced when broken down
       • Short lived immunity
   • Active
     • Stimulating the production of antibodies by the individuals own immune system
     • Can provide herd immunity

2. Successful vaccination programme

   • Suitable vaccine must be economically available in sufficient quantities to immunise all of the vunerable population
   • Few side effects to encourage individuals to get vaccinated
   • Producing, storing and transporting must be available
   • Must be a way to administer properly, so training staff
   • Must be possible to vaccinate the vast majority of the vulnerable population

3. Why does vaccination not eliminate a disease?

   • Fails to induce immunity in certain individuals
   • Disease may develop immidiately after vaccination, but before immunity levels are high enough for prevention
   • May be mutations
     • New antigens change suddenlym meaning that the antigens are no longer recognised
     • This is antigenic variability
   • Lots of varieties of a particular pathogen
   • Pathogens can hide from the immune system
     • Conceal themselves inside of living cells
     • Living in places out of reach
   • People may have objections to vaccinations

4. Problems with control of cholera

   • Intestinal, so not easy to reach
   • Oral treatment rarekly has time to be effective as it is rapidly flushed from the intestines
   • Antigenic variability
   • Mobile populations make it difficult to ensure individuals are vaccinated

5. Problems with control of TB

   • Increase in HIV meaning more impaired immune systems
   • Refugees move and are housed in overcrowded places
   • Mobile populations make it difficult to vaccinate everyone
   • Aging population with less effective immune systems

6. MMR Vaccine

   • 1988, combined vaccine for mumps, measles and rubella
   • 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
   • Many parents decided to have individual vaccinations, or not have their children vaccinated at all
   • Incidence of mumps, measles and rubella rose
   • Since the report was published, it has been found
     • Author had a confict of interests
       • Was being paid by the Legal Aid Board to discover whether parents who claimed their children had been damaged by MMR had a case
     • Further studies have found no link
     • Sample size was small
     • The journal that published the initial research has publicly declared that, had it known all the facts, it would not have published the work
   • Theories must be initially treated with caution
     • Must be peer reviewed
     • Scientists may have vested interests
     • Personal beliefs, views and opinions may influence the way they approach or represent their research
     • Facts presented may have been biased or distorted to suit the presenters interests
     • New knowledge may challenge scientific beliefs

7. Ethics of vaccination

   • Often involves use of animals
   • Side effects which may cause long-term harm
   • Who should vaccines be tested on and how should such trials be carried out
   • 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?
   • Most if not all of the population should be vaccinated - is it fair for vaccination to be compulsary?
   • Should expensive vaccinations continue even when the disease has almost been eradicated if it means less money for the treatment of other diseases
   • How can individual health risks from vaccination be balenced against the advantages of controlling a disease for the benefit of the population at large?