How a Vaccine Works - Free Educational videos for Students in K-12

How a Vaccine Works - By MITK12Videos

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00:05	How does the vaccine work ? Have you ever wondered
00:11	why getting a vaccine prevents you from getting sick in
00:14	the future ? While it might not look like it
00:17	are , everyday environment is actually filled with pathogens ,
00:22	tiny organisms too small to see that can make you
00:25	sick . So how does our body keep healthy ?
00:33	Our immune system keeps us healthy normally . It has
00:36	white blood cells which act like soldiers in our blood
00:40	that work to fight off invaders , like foreign viruses
00:43	or bacteria that do not belong in the body .
00:48	Just like soldiers need practice to prepare against an attack
00:52	. Our immune system works best when defending against the
00:56	pathogen . It has already encountered . A vaccine functions
01:01	like a practice run , allowing our body to build
01:04	up defenses before encountering a pathogen such as a virus
01:09	. Let's take a closer look when the immune system
01:13	first encounters something for in the body takes a while
01:16	to figure out how to fight or counter it .
01:21	This is because there are many different immune cells working
01:24	together , just like there are many different jobs within
01:28	an army patrolling cells called macrophages are the first ones
01:33	to meet or encounter pathogens , but it doesn't stop
01:38	. There . Also involved in helping the body fight
01:41	off diseases are two types of cells called B and
01:45	T cells , B and T cells work together to
01:49	make antibodies , antibodies prevent the invading virus from doing
01:54	harm , but only some antibodies will work against the
01:58	virus in order to fight off the pathogen . The
02:03	macro fish needs to find the right few B or
02:06	T cells out of all the cells in the body
02:09	that will make the right antibodies . It's like finding
02:13	a needle in a haystack , but what exactly determines
02:19	which B and T cells will work against the virus
02:23	. And what do these cells do ? Each B
02:28	or T cell makes proteins of unique shape on its
02:32	outside surface , which are called receptors . Every virus
02:36	also has different shapes on its surface . These are
02:40	antigens . Antigens tell the body that the virus is
02:44	a pathogen and is something that should not belong .
02:48	The body just like different keys fit different locks .
02:54	Each viruses antigens fit different B or T cells .
03:00	If a cell has a receptor which matches the antigen
03:04	of a virus , it becomes activated and divides ,
03:08	producing huge quantities of antibodies to disable the virus To
03:13	be exact up to 1000 antibodies per second . So
03:20	what does this all have to do with vaccines ?
03:24	Vaccines expose the body to a weakened version of the
03:27	virus , even though the virus and the vaccine cannot
03:31	harm you . Your immune system still recognizes it as
03:35	an enemy in response . The body creates a special
03:39	kind of B cell called a memory cell . Memory
03:43	cells remember which antibodies work against a specific threat after
03:50	vaccination . If your body is exposed to the actual
03:53	full strength virus , the body already has memory cells
03:57	meaning it can destroy the virus much faster and more
04:01	effectively . Thus a vaccinated person is immune to the
04:07	virus he or she was vaccinated for mm . Take
04:13	a look at the graph of the number of antibodies
04:16	made in the body over time . The first peak
04:20	shows the amount of antibody produced . The first time
04:23	the body sees of particular virus . This first exposure
04:28	could be from a vaccine like we have been talking
04:31	about . Yeah . Remember the vaccine shows the body
04:35	weak viruses . So the person usually doesn't get sick
04:39	when they first see the virus . This could also
04:42	happen when a person gets sick from a virus they
04:45	haven't had before . For example the first time someone
04:49	has a chicken pox virus and gets a rash as
04:52	their body tries to figure out how to fight the
04:55	virus . The second peak is the amount of antibodies
05:00	produce . If the body seized the same virus a
05:03	second time , you see that the second exposure produces
05:07	more antibodies in a shorter time than the first exposure
05:11	to a pathogen . In other words , if the
05:15	immune system goes up against the virus , it has
05:17	seen before , the responses faster and stronger and you
05:22	don't get sick a second time . This is why
05:27	if you've had chickenpox or if you were vaccinated for
05:30	it , you don't have chickenpox again . Your body
05:34	has already encountered the virus through either or shot or
05:38	just by overcoming the chicken pox virus naturally . There
05:44	have been many successful vaccines for diseases such as polio
05:48	, smallpox and Hepatitis B . However , some viruses
05:56	mutate or change too quickly for a single vaccine to
05:59	be effective . this means the antigen shapes on their
06:03	surfaces are constantly changing . The immune system can't make
06:08	antibodies that work for a long time because the antibody
06:11	won't match the viruses and trojan after the virus mutates
06:17	. This is why there is no vaccine for HIV
06:20	and you are recommended a new flu shot every year
06:23	because these viruses change quickly . Now let's go back
06:30	to the vaccine boy . There's nothing magical about the
06:34	vaccine . Boy . Getting a vaccine just primes his
06:37	body's immune system , making him more prepared to defend
06:41	against specific invaders . By getting vaccinated . You train
06:47	your immune system to fight off pathogens , making it
06:51	less likely you'll get sick . Mhm .

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