topic 2: vaccines & immunity

Question 1

what do vaccines contain?

Answer 1

antigens derived from pathogenic organisms

Question 2

what happens to the immune response as a result of vaccines?

Answer 2

when a person comes into contact with that microorganism again, the secondary response will be rapid and the person is unlikely to develop that disease

Question 3

a vaccine leads to the production of antibodies against a pathogen. How?

Answer 3

1. the vaccine contains the antigen from the pathogen
2. phagocytes present antigens on their surface
3. T Helper cells with a complementary receptor protein bind to the antigen
4. TH cells stimulate b cells with complementary antibodies on their surface
5. B cells form plasma cells, which produce large amounts of the same antibody

Question 4

what are the 2 types of vaccine?

Answer 4

live/attenuated
killed/dead/inactivated

Question 5

what are live/attenuated vaccines?

Answer 5

contain viruses that have been weakened, but not destroyed in a laboratory

Question 6

example of a live/attenuated vaccine

Answer 6

MMR

Question 7

what is a killed/dead/inactivated vaccine?

Answer 7

contains viruses that have been destroyed with chemicals or heat

Question 8

example of a dead/inactivated vaccine

Answer 8

flu vaccine

Question 9

2 types of immunity

Answer 9

active
passive

Question 10

what is active immunity?

Answer 10

develops when a person is exposed to microorganisms or foreign substances and the immune system responds

Question 11

what is passive immunity?

Answer 11

acquired when antibodies are transferred from one person to another
the recipient doesn’t make the antibodies themselves, and the effects only last as long as the antibody is present

Question 12

give an example of passive immunity

Answer 12

from the mother to baby via placenta or milk
the antibodies that a baby receives via the placenta will eventually be destroyed by the baby’s immune system

Question 13

how is active natural immunity acquired?

Answer 13

by contracting the disease and suffering the symptoms

Question 14

what is the duration of active natural immunity?

Answer 14

long lasting
memory b and memory t cells are made

Question 15

how is active artificial immunity acquired?

Answer 15

vaccines with dead or weakened microbe

Question 16

what is the duration of active artificial immunity?

Answer 16

long lasting
memory B and T cells made

Question 17

how is passive natural immunity aquired?

Answer 17

antibodies across the placenta to the fetus or breast milk to the baby

Question 18

what is the duration of passive natural immunity?

Answer 18

short lived - no memory cells made
maternal antibodies are recognised as antigens and are destroyed by fetal lymphocytes

Question 19

how is passive artificial immunity acquired?

Answer 19

vaccines with antibodies
used for Rabies, anti-D for rhesus negative mothers

Question 20

what is the duration of passive artificial immunity?

Answer 20

short lived- no memory cells made

Question 21

compare passive and active immunity

Answer 21

-active involves memory cells, passive doesnt
-antibodies are produced by plasma and memory cells in active, they are introduced from outside the body in passive
- active is long term because the antibody is produced in responce, passive is short term because antibody is broken down
- active can take time to develop, passive is fast acting

Question 22

give 6 features of a successful vaccination programme

Answer 22

1. suitable vaccine- economically available/in sufficient quantity
2. few side effects
3. the means to produce,store and transport it
4. trained staff to administer it
5. public awareness
6. try to vaccinate the majority of the population at one time

Question 23

why is it important in a vaccination programme to try and vaccinate the majority of the population at one time?

Answer 23

to interrupt transmission of the pathogen- herd immunity

Question 24

what is herd immunity?

Answer 24

the percentage cover or proportion of individulas who must be immune to a disease in order to prevent an epidemic?

Question 25

what is the importance of herd immunity?

Answer 25

if enough of the ‘herd’ is protected by the vaccine, the disease can only affect isolated individuals so cant spread
the chance of coming into contact with an infected person is reduced

Question 26

what happens if fewer people are vaccinated?

Answer 26

once vaccine level drops, more individuals will contract the disease and transmit to other unprotected individuals
recently the lack of uptake of MMR vaccine has lead to outbreaks of measles in london because of a fall in % cover

Question 27

polio epidemics can be prevented by what % cover?

Answer 27

70

Question 28

influenza epidemics can be prevented by what % of cover

Answer 28

90-95

Question 29

give 4 possible reasons as to why vaccines dont necessarily eliminate disease

Answer 29

• may not work for people whos immune system doesnt function properly
  -some pathogens mutate frequently- antigenic variability
• individual may develop disease immediately after vaccination and pass it on
  individuals may object for religious, ethical or medical reasons

Question 30

give some ethical considerations regarding vaccine programmes

Answer 30

• side effects may have LT harm
• should vaccination be compulsory?
• who should vaccines be tested on?
  -production/development of new vaccines often involves animals
  -should an expensive vaccine program be undertaken if the disease is nearly eradicated?