Biology B2

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Edward Jenner invented vaccinations when observing that milk maids who had sufferered from the mild disease of cowpox never caught the deadly smallpox. He injected a young boy with the pus of a milkmaid suffering from cowpox. After he recovered, he injected the boy with pus from someone suffering from smallpox. Within a few days, the boy fully recovered and showed no sign of having smallpox. This is how the first vaccination was created.

The explanation is that both pathogens in smallpox and cowpox have the same shaped antigens. Therefore, when the person fights off the coxpox, their immune system has made memory cells that will remember the antibodies so that it can produce them quickly if the disease enters the body again. Now when the person is infected with smallpox, the immune system has already got the antibodies for the white blood cells to use against the pathogen.

A vaccination contains a dead or weakened version of the pathogen. These still contain the same antigens as the fully active version of the pathogen so the immune system is able to store the antibodies for the white blood cells to use if the pathogen enters the body again. An example is the MMR vaccine (measles, mumps, rubella).

It is important to ensure that everybody is vaccinated to prevent epidemics (big outbreaks of a disease). By vaccinating everybody, a disease is less likely to spread drastically because most people who are affected should recover quickly.

Unfortunately, sometimes microbes can develop random mutations, which lead to them being unaffected by the old antibodies made in the immune system because the shae of its antigens has changed. This can lead to antimicrobials being unaffective and the microbe turning into a superbug. Antimicrobials are chemicals that inhibit the growth of micro-organisms. Antibiotics are a form of antimicrobials, which kill bacteria. If you do not finish the full course of antibiotics that you are meant to take, the bacteria become resistant and harder to kill.

Clinical Trials:

Drugs are first tested in a lab on genetically developed human cells and then live mammals, which have similar cell and brain structure to humans (rats and monkeys).

Now, a clinical trial is set up to test the drug on a group of human volunteers, who are healthy. There are three different types of trials: blind, double-blind and open-label.

Blind trials are when only the doctor know whether the patient has been give the real drug or the placebo.

Double blind trials are when neither the patient or doctor knows whether the patient has been given the real drug or not.

Open-label trials are when both the doctor and patient know whether the real drug has been prescribed to the patient or not.  

Unfortunately some people are negatively effected as a result of unexpected side-effects from the drug. This is where human ethics come in because some people are being harmed and that is against human rights. On the other hand, they have volunteered for this and are aware of a…


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