AS Biology 6.6 Vaccination

Reasons to treat scientific evidence with caution.

1. A scientific theory must be critically appraised and confirmed by other scientists in the field. 2. Some scientists may have vested interests. 3. Scientists' personal beliefs, view and opinions may influence the way they approach or represent their research. 4. Fasts presented by media, companies and governments etc. may have been biased or distorted to suit their own interests. 5. New knowledge may challenge accepted scientific beliefs; theories are being modified all the time.

3 reasons why control of cholera by means of vaccination is difficult because:

1. Cholera is an intestinal disease and therefore not easily reached by the immune system. Any oral treatment i.e. antibiotics are flushed out from the intestines by diarrhoea before it has time to be efficacious.  2. Antigenic variability of cholera 3. Mobile populations makes it difficult to ensure that people are vaccinated.

5 Features of a successful vaccination programme.

1. Economically viable to immunise the whole population. 2. Few side affects so people will be will to be vaccinated. 3. Production and storage of the vaccine bust be available, for example, most require refrigeration. 4. Means of administering vaccine must be available at the right time. (Initial vaccinations are often followed by booster vaccinations). Staff require training. 5. Vaccination of the whole population and preferably at the same time to halt the progress of the infection. (Herd immunity)

4 reasons why control of tuberculosis by vaccination is difficult

1. HIV has led to more people with impaired immune systems. 2. Poverty, wars and political unrest have created refugees who move around frequently and are housed in overcrowded temporary accommodation. 3. Mobile populations have spread the disease worldwide and make it harder to ensure that individuals are vaccinated. 4. Proportion of elderly in the population is increasing, their immune systems are less effective so vaccination is less effective at simulation immunity.

Following the first research linking the MMR vaccine to autism a number of facts have emerged.

1. The author of the research had a conflict of interests; he was representing families in compensation claims against MMR. 2. Further studies, including one in Japan of 30,000 children have found no link between the MMR vaccine and autism. 3. The sample size of the initial research was very small relative to later studies. 4. The journal that published the initial research later stated that had they known all the facts they would not have published the research.

Ethical considerations of vaccines.

1. Use of animals in research and development. 2. Side effects vs. benefits. 3. Who do we test on? Populations were the condition is most prevalent, i.e. ORT - many people would die if not given the appropriate treatment. 4. Should vaccination be obligatory to preserve herd immunity. Who, for what reason would be allowed to opt out? 5. Should we continue to vaccinate against diseases which are almost eradicated, this costs money, why not spend money vaccinating against more prevalent diseases. 6. How can individual health risks from vaccination be balanced against the advantages of controlling disease for the benefit of the population.

6 Reasons why vaccination does not eliminate disease

1. Vaccination does not work for all. 2. Individuals may develop the disease before their immune systems produce immunity, so harbour the disease and go on to infect others. 3. Antigenic variability. 4. May be many strains of the pathogen so difficult to produce an effective vaccine, i.e. the common cold. 5. Some pathogens cannot be located by the immune system. For example if they are in difficult locations such as Cholera. 6. Some people do not believe in vaccination for ethical, religious or cultural reasons

Two forms of immunity

Active and Passive Immunity

MMR

Combined vaccine for measles, mumps and rubella.

Active Immunity Definition

Resistance to disease resulting from the activities of an individual's own immune system whereby an antigen induces plasma cells to produce antibodies.

Passive Immunity Definition

Resistance to disease that is acquired form the introduction of antibodies from another individual, rather than an individual's own immune system, e.g. across the placenta or in the mother's milk. It is usually short-lived.

Immunity

The ability of an organism to resist infection.

Vaccination Definition

The introduction of a vaccine containing appropriate disease antigens into the body by injection or mouth in order to induce artificial immunity.