Understanding Vaccines What They Are How They Work - VIOLIN

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How Vaccines Work The Immune System To understand how vaccines teach your body to fight infection, let’s first look at how the immune system fends off and learns from a naturally occurring infection. Then we’ll examine how vaccines mimic this process. Imagine you are a dock worker on the piers of Philadelphia. The year is 1793. As you are unloading crates of tea and spices from an oceangoing ship, a mosquito bites you on the arm. This mosquito carries the virus that causes yellow fever, which the mosquito picked up when it bit a sailor who recently returned from Africa. So now you have thousands of yellow fever viruses swarming into your body. In fact, you have become part of an infamous epidemic that will claim the lives of 10 percent of the people in Philadelphia, and all that stands between you and a fatal case of yellow fever is your immune system. Your immune system is a complex network of cells and organs that evolved to fight off infectious microbes. Much of the immune system’s work is carried out by an army of various specialized cells, each type designed to fight disease in a particular way. The invading viruses first run into the vanguard of this army, which includes big and tough patrolling white blood cells called macrophages (literally, “big eaters”). The macrophages grab onto and gobble up as many of the viruses as they can, engulfing them into their blob-like bodies. UNDERSTANDING VACCINES 11
12 A mosquito bite transmits the yellow fever virus to an unsuspecting dock worker. In 1793, a yellow fever epidemic claimed the lives of 10 percent of Philadelphians. How do the macrophages recognize the yellow fever virus? All cells and microbes wear a “uniform” made up of molecules that cover their surfaces. Each of your cells displays marker molecules unique to you. The yellow fever viruses display different marker molecules unique to them. The macrophages and other cells of your immune system use these markers to distinguish among the cells that are part of your body, harmless bacteria that reside in your body, and harmful invading microbes that need to be destroyed.
Page 1 and 2: Understanding nderstanding VACCINES
Page 3 and 4: Contents 1 2 4 6 11 21 36 38 43 47
Page 5 and 6: What Is aVaccine? 2 Chances are you
Page 7 and 8: Vaccine Benefits 4 You and Your Com
Page 9 and 10: Harmful Microbes 6 Vaccines protect
Page 11 and 12: 8 • The toxic bacterium Bordetell
Page 13: 10 What Do Cows Have to Do with Vac
Page 17 and 18: 14 T Cells T cells function either
Page 19 and 20: T cell B cell 16 Virus B cell Antib
Page 21 and 22: 18 fever antibody if needed. Memory
Page 23 and 24: 20 How Viruses Work Viruses such as
Page 25 and 26: 22 Live, Attenuated Vaccines Some s
Page 27 and 28: 24 Inactivated Vaccines An inactiva
Page 29 and 30: 26 They also could manufacture the
Page 31 and 32: 28 When making a conjugate vaccine,
Page 33 and 34: 30 So-called naked DNA vaccines con
Page 35 and 36: 32 An infant’s immune system cont
Page 37 and 38: Some Vaccine Types and Diseases The
Page 39 and 40: Vaccines of the Future 36 Aside fro
Page 41 and 42: Making Safe Vaccines 38 No vaccine
Page 43 and 44: 40 Because Phase III trials are com
Page 45 and 46: Vaccine Concerns, Myths, and Safety
Page 47 and 48: 44 testing sites are based at unive
Page 49 and 50: 46 system’s response to HIV infec
Page 51 and 52: Glossary 48 adjuvant—a substance
Page 53 and 54: 50 DNA vaccine or naked DNA vaccine
Page 55 and 56: 52 lymph node—a small bean-shaped
Page 57 and 58: 54 recombinant subunit vaccine—a
Page 59: U.S. DEPARTMENT OF HEALTH AND HUMAN

Understanding Vaccines What They Are How They Work - VIOLIN

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