Vaccines

• 1.20 Be able to describe Edward Jenner’s contribution to the development of vaccines.
• 1.21 Be able to explain the process of immunisation, including:
  • a) harmless pathogen or antigenic material introduced
  • b) the antigens trigger an immune response which causes the production of antibodies
  • c) the antigens also trigger production of memory lymphocytes
• 1.22 Be able to demonstrate an understanding of the advantages and risks associated with immunisation.
• 1.23 HT only: Be able to describe the role of memory lymphocytes in secondary responses to antigen; interpret data showing variation in blood antibody levels in response to first and subsequent infections.

Edward Jenner

Edward Jenner was an English scientist who lived in the 18th century. He discovered the first vaccine, which was for the smallpox virus. This disease was widespread in the 18th century and killed many people. Those who were infected but survived were often left badly scarred.

Jenner noticed that milkmaids who had caught the cowpox virus did not normally then catch smallpox. Cowpox was very similar to smallpox but lesscontagious.

He collected pus from the cowpox blisters on a milkmaid’s hands and purposefully infected a small boy. The boy was taken ill for a short while, but was then resistant to any subsequent infections of the cowpox and smallpox viruses. He tested this by infecting the boy with smallpox. No illness occurred. Jenner was therefore the first person to vaccinate someone against infection.

• 1.21 Be able to explain the process of immunisation, including:
  • a) harmless pathogen or antigenic material introduced
  • b) the antigens trigger an immune response which causes the production of antibodies
  • c) the antigens also trigger production of memory lymphocytes

This all seems pointless, except for the fact that once your body has been exposed to an antigen, it remembers and produces antibodies much faster the next time it is exposed to the antigen, which will probably be when you are infected with the real microorganism! You body fights it so quickly, that you don't even realise you had it!. 

• 1.22 Be able to demonstrate an understanding of the advantages and risks associated with immunisation.

Advantages and disadvantages of vaccinations

The advantages of vaccinations are obvious - they stop individuals becoming ill. If enough people are vaccinated, vaccinations can also stop pathogens infecting whole populations. This is called herd immunity.

There are also risks to having vaccinations. For instance, some people suffer from a mild reaction to the vaccine.

In recent years there has been much controversy surrounding the MMR vaccine. Some people used to think the vaccine - which is a combined treatment against  measles,  mumps  and  rubella - could cause autism in children. They decided not to risk letting their child have the vaccine and just hoped they would not catch measles, mumps or rubella.

But this meant that, as fewer and fewer children were vaccinated, the three diseases began to spread more easily and the number of cases began to increase. More recent studies by the World Health Organisation have shown that there is no link between the MMR vaccine and autism.

Vaccinations can never be completely safe because side-effect levels vary. So, when making a decision, these are some of the factors that need to be considered:

• when fewer people are vaccinated, the number of cases of the disease increases
• the chance of falling seriously ill or dying from the disease may be far greater than the chance of experiencing a serious side-effect
• using a vaccine may be much cheaper than treating a very ill person

Most of this writing was copied from BBC Bitesize - an awesome site from which you can begin your revision!