5.6 Vaccination

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  • 5.6 Vaccination
    • Immunity = ability org to resist infect.
    • Passive immunity
      • Prod -intro ab into individ - outside source. No direct contact w/ path/ its nec AG to induce immunity - acquired immediately. AB ? prod by individ, broken - not replaced.
        • No mem cells = NO LASTING IMMUNITY
      • E.g. anti-venom - snake bites. Fetus immunity - AB pass placenta from mother
    • Active immunity
      • Prod  - stim prod AB from individs own IS. Direct contact w/ pathogen/ ag nec. Im takes time develop.
        • LONG LASTING. Natural active immunity (individ infected w/ disease(normal))
          • Body prod own ABs cont.
      • Artificial active immunity - vaccination/ immunisation. Invl inducing Im response w/o symptoms disease.
    • Features successful vaccination programme
      • Precautionary measure. Not treatment
      • Is it economically available?
      • Does it have few side effects? Unpleasant = discouraged
      • Has it means of pro, storing & transport? hygiene + refrigeration...
      • Administered properly - staff trained
      • Vast majority people had = herd immunity
    • Herd immunity
      • Arises - sufficiently ^ proportion been vac - diff path spread.
      • concept = path passed individ -> individ close contact. If vast maj immune, highly improbable individ contact infected person. Ven not immune - other individ protected.
      • Import bc not poss vac everyone. e.g. babies & young children ? vac bc IS not fully func. OR compromised IS.
        • To achieve HI - best carried out 1 time so transmission pathogen interrupted
    • Why vaccination may not eliminate disease
      • Vacc fails induce immunity certain individ e.g. defective IS
      • Individ develop disease immed after vac, before I levels ^ enough to prevent it - reinfect others
      • pathogen mutate freq, ag change suddenly rather than gradually = vac ineffective bc new ag no longer rec by IS. As result IS ? prod ab destroy path. Antigenic variability
      • So many varieties almost imposs develop vac 4 all. e.g. over 100 varieties common cold  & evolving.
      • certain path 'hide' body's IS, concealing selves inside cells/ out reach places like intestines (cholera)
      • Inidivid object to vac for religious/ ethical/ medical reasons e.g. unfounded concerns over MMR vac causing autism
    • The ethics of using vaccines
      • Prod existing vac & develop uses animals.
      • Vacc - side effects - sometimes long-term harm.
      • On who vac tested? how trials carried out? accept risks in interest public health?
      • Fully effective, majority/ prefer all should b vac - should be compulsory?
      • How can any individ health risks from vac balanced against adv contr disease for ben pop @ large

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