Unit 3 KA7 - immunisation

Question 1

what is immunisation?

Answer 1

the process by which a person develops immunity to a disease-causing organism

Question 2

what is meant by active immunity?

Answer 2

the protection gained as a result of a person producing their own antibodies

Question 3

a vaccine contains….

Answer 3

a form of the anitgen carried by the diease causing pathogne and triggers an immune response in the same way the real pathogen would without the illness

Question 4

antigens used in vaccines can be….

Answer 4

inactivated pathogen toxins, dead pathogens, parts of pathogens or weakened pathogens

Question 5

how is a vaccine made?

Answer 5

the antigen of choice is mixed with an adjuvant

Question 6

what is an adjuvant?

Answer 6

a chemical substance that promotes the activity of the antigen and enhances the immune response

Question 7

how is an artificial primary response triggered?

Answer 7

by lymphocytes by exposing individuals to the antigen in a vaccine

Question 8

what is the role of an artificial primary response?

Answer 8

it creates memory cells which will immediately react to the pathogen on subsequent exposure

Question 9

what is herd immunity?

Answer 9

a form of protection where a large percentage of a population is immunised so that non-immune individuals are protected as there is a lower chance they will come into contact with infected individuals

Question 10

why is herd immunity important?

Answer 10

to reduce the spread of diseases and protecting vulnerable and non-vaccinated individuals

Question 11

what is the herd immunity threshold?

Answer 11

the minimum percentage of immune individuals in a population to prevent a disease

Question 12

what does the herd immunity threshold depend on?

Answer 12

• the pathogen’s virulence (capacity to cause disease)
• efficacy of the vaccine
• density of population

Question 13

why are mass vaccination programs used?

Answer 13

as part of the public health policy for combatting common diseases

Question 14

why is widespread vaccination not fully possible for developed and developing countries?

Answer 14

developed - rejection due to negative publicity about the vaccine
developing - poverty

Question 15

what is an antigen?

Answer 15

molecules, often proteins, located on the surface of cells that trigger a specific immune response
all cells have antigenic markers on their surface

Question 16

describe the meaning of antigenic variation and what this results in

Answer 16

some pathogens evolve to produce new antigens which result in memory cells being ineffective against them

Question 17

what is the negative impact of antigenic variation?

Answer 17

it allows the virus to re-infect individuals as the new antigens are not recognised by memory cells

Question 18

what can be done for high-risk people in terms of antigenic variation?

Answer 18

they must be vaccinated every year with ha new version of the vaccine