Vaccinations

Starter What are the two ways that white blood cells fight infection? How do we acquire immunity?

Lesson objectives To be able to explain how vaccination works (C ) To be able to understand the historical development of vaccination (C ) To understand herd immunity (C ) To be able to weigh up some of the pros and cons of vaccinations (B-A* ) To understand the problems in developing vaccinations against influenza and HIV (B-A*)

Now… Brainstorm- what do you already know about vaccinations? What vaccinations have you had? Why are vaccinations important?

What do you think this 1802 cartoon refers to?

Eradicating smallpox Smallpox used to be one of the deadliest of infectious diseases. Caused by virus- airbourne transmission and through contact with an infected person. Causes pustules to rise on the skin and eyes, eventually covering the body and high fever. Between 20 and 60 percent of all people infected, and up to 80 percent of all children infected, died of smallpox. Those who survived were often disfigured or blind.

What was done to fight smallpox? Variolation—the deliberate infection with smallpox was a technique that developed in Asia and spread to the west by the 1700’s Smallpox scabs were blown into the nose or added to a cut in the skin who then contracted a mild form of the disease. Upon recovery, the individual was immune to smallpox. Between 1% to 2% of those variolated died as compared to 30% who died when they contracted the disease naturally. Inoculation used a less virulent strain of smallpox, which made it safer than catching smallpox during an outbreak.

Who developed vaccinations? Vaccinations were developed by Edward Jenner in 1796 http://www.bbc.co.uk/learningzone/clips/edward-jenner-the-discovery-of-smallpox-vaccine/2456.html How did Edward Jenner develop vaccination? Explain his discovery- Either in a paragraph, flow-chart or cartoon strip. Two hundred years ago smallpox was still a major disease. Edward Jenner was a doctor. He noticed that people who worked with cattle, like milkmaids, didn’t catch smallpox. He saw that milkmaids got poxes on their hands similar to those of smallpox.The poxes were caused by a harmless disease called cowpox. Jenner wondered if catching cowpox made the milkmaids immune to smallpox. He decided to take some cowpox pus from a milkmaid and scratch it into the arm of a young boy called James Phipps. James then got cowpox. Later on Jenner scratched some smallpox into James’ arm to see if he would catch smallpox. He didn’t!

Jenner saw a problem that people were dying of smallpox. Jenner put the smallpox pus into James’ arm. James got cowpox and was ill for a few days. Jenner made some cuts on James’ arm and put Sarah’s pus in to it. Jenner decided that his hypothesis had been correct – cowpox had provided protection from cowpox. Jenner then collected some pus from a smallpox victim. James did not get smallpox. Jenner chose a young boy who had not had either disease. He was called James Phipps. Jenner noticed that milkmaids who got cowpox didn’t seem to get smallpox. James recovered from cowpox. Jenner collected some pus from a cowpox spot from Sarah the milkmaid. Jenner decided to test his ideas out by doing an investigation Jenner formed a hypothesis (idea) that cowpox provided some protection against smallpox.

What do vaccines contain? Vaccination involves putting a small amount of an inactive form of a pathogen (disease causing micro-organism) into the body. Vaccines can contain: live pathogens treated to make them harmless harmless fragments of the pathogen toxins produced by pathogens dead pathogens

How do they work? These all act as antigens. When injected into the body, they stimulate white blood cells to produce antibodies to fight the pathogen. The vaccine contains only a weakened or harmless version of a pathogen, which means that the vaccinated person is in no danger of developing the disease. Some people, however, may suffer a mild reaction. If the person later becomes infected with the pathogen, the required lymphocytes are able to reproduce rapidly and destroy it.

http://www. abpischools. org http://www.abpischools.org.uk/page/modules/infectiousdiseases_immunity/immunity6.cfm Put the sentences in the correct order

Herd immunity What is herd immunity? For a vaccination programme to be successful, it depends on herd immunity. If the majority of a population is vaccinated, not only are those people kept safe, but viruses cannot spread between immunised people. The immunised people provide a barrier that stops the infection from spreading to others in the group. If only a few people are vaccinated, this will help them avoid infection, but it will not protect the group. Based on this should people be forced to have vaccinations?

Are vaccinations safe? Vaccinations can never be completely safe because side-effect levels vary. So, when making a decision, these are some of the factors that should 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.