Vaccines 101: How vaccines work — Transcript

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1. 0:00vaccines have an important role in
2. 0:02protecting us
3. 0:03from infectious disease but how do they
4. 0:05work
5. 0:07well put simply vaccines train our
6. 0:10immune system to detect
7. 0:11and attack pathogens and we're going to
8. 0:14walk you through how they do it
9. 0:16from start to finish our immune system
10. 0:19is a marvelously complex network of
11. 0:22molecules and cells
12. 0:24which has the power to destroy pathogens
13. 0:26like viruses and bacteria
14. 0:29the part of the immune system that
15. 0:30vaccines train is called the adaptive
16. 0:33immune system
17. 0:34its first job is to recognize an invader
18. 0:38in the case of this bacterium it does
19. 0:40this by detecting molecular markers
20. 0:42called antigens that are part of all
21. 0:44pathogens
22. 0:46after detecting an antigen the adaptive
23. 0:48part of the immune system
24. 0:50starts mounting a bespoke response
25. 0:53b cells convert to plasma cells and
26. 0:55start creating proteins called
27. 0:57antibodies
28. 0:58which bind specifically to the antigen
29. 1:00together with immune cells called
30. 1:02phagocytes
31. 1:03antibodies can destroy the pathogen
32. 1:06the adaptive immune system also produces
33. 1:09killer t
34. 1:10cells which have the ability to detect
35. 1:12and destroy
36. 1:13cells infected with the pathogen but it
37. 1:16doesn't end there
38. 1:18to prevent against future infections the
39. 1:20adaptive immune system
40. 1:22also has a memory it produces long-lived
41. 1:25memory cells which lie in weight ready
42. 1:27to pump out the right antibodies and
43. 1:29killer t cells
44. 1:30if the same pathogen is ever seen again
45. 1:33this is called immunity vaccines work
46. 1:37by activating the adaptive immune system
47. 1:40and so
48. 1:40creating immunity they safely introduce
49. 1:44antigens
50. 1:44for the immune system to train on
51. 1:46preparing itself to fight
52. 1:48real infections in the future so what
53. 1:51actually goes
54. 1:52into a vaccine well there are several
55. 1:55different types
56. 1:56one of the most common are called live
57. 1:58attenuated vaccines
58. 2:01these include things like mmr or bcg
59. 2:04live attenuated vaccines work by
60. 2:07introducing a weakened version of a
61. 2:08living pathogen
62. 2:09into the body these attenuated pathogens
63. 2:13are not strong enough to cause disease
64. 2:15in people with healthy immune systems
65. 2:17but they can still trigger a strong
66. 2:19immune response
67. 2:21live attenuated vaccines trigger a
68. 2:23similar immune response to a real
69. 2:25infection
70. 2:26leaving behind the same memory cells
71. 2:28this means that some can provide a
72. 2:30lifetime of protection after just one or
73. 2:33two doses
74. 2:35another key type of vaccine is called a
75. 2:37subunit or recombinant vaccine
76. 2:40they work differently instead of a live
77. 2:43sample
78. 2:44subunit vaccines contain only part of
79. 2:46the pathogen
80. 2:47for instance the vaccine for human
81. 2:49papilloma virus
82. 2:51hpv uses hollow virus-like particles
83. 2:54made from a protein
84. 2:55found in hpv
85. 2:59alone these subunits cannot get the
86. 3:01immune system's attention
87. 3:02and so they need a bit of help from
88. 3:04another ingredient
89. 3:06an adjuvant adjuvants wake up the immune
90. 3:10system
91. 3:11triggering it to see the subunit
92. 3:13antigens and start creating antibodies
93. 3:15and memory cells
94. 3:18subunit vaccines contain no life
95. 3:21pathogens
96. 3:22and so lack the genetic information
97. 3:24needed to replicate
98. 3:26that means they are not infectious and
99. 3:28are safe even for people with weakened
100. 3:30immune systems
101. 3:32great but generally they don't trigger
102. 3:35the production of as many memory cells
103. 3:37compared to live attenuated vaccines and
104. 3:40so
105. 3:41they don't provide such long lasting
106. 3:43protection
107. 3:45training the immune system through
108. 3:46vaccination helps to protect
109. 3:48individuals from infection but vaccines
110. 3:51can also protect people who can't
111. 3:53receive them
112. 3:54this is called herd protection or herd
113. 3:57immunity
114. 3:59herd immunity is created when a large
115. 4:01percentage of a population
116. 4:03is immune to a disease it works by
117. 4:07disrupting
118. 4:08chains of infection without new hosts to
119. 4:11infect
120. 4:12pathogens can't survive that means that
121. 4:15if a pathogen tries to infect someone
122. 4:16who is vaccinated
123. 4:18and so immune it dies and the chain of
124. 4:20infection
125. 4:21is broken if enough chains are broken in
126. 4:24a population
127. 4:25it becomes very difficult for pathogens
128. 4:28to reach those who would be vulnerable
129. 4:31herd immunity protects millions of
130. 4:33people around the world
131. 4:34but if vaccination rates drop there is a
132. 4:37risk the diseases
133. 4:38can reappear for example measles was
134. 4:41declared eradicated in the united states
135. 4:44in 2000
136. 4:45but since then falling vaccination rates
137. 4:48have led to a resurgence of the disease
138. 4:50with outbreaks recorded
139. 4:51in 31 states if herd immunity is
140. 4:55maintained
141. 4:56for long enough though diseases can be
142. 4:58eradicated completely
143. 5:00for example smallpox which is estimated
144. 5:03to have killed
145. 5:03300 million people in the 20th century
146. 5:06is now considered
147. 5:07extinct all thanks to vaccination
148. 5:11its training regime and the wonders of
149. 5:14herd immunity
150. 5:27[Music]
151. 5:30you