Immunisation & Infection Prevention

Question 1

What are the reasons for immunisation?

Answer 1

• Protects individual & communities
• Proactive measure for well people
• Reflects NHS & professional quality

Question 2

What are the strategic aims of vaccination?

Answer 2

• Elimination-herd immunity
• Eradication
• Selective protection of the vulnerable

Question 3

What are the programmatic aims of vaccination?

Answer 3

• Prevents death
• Prevents infection
• Prevents transmission
• Prevents cases in certain age groups
• Prevents clinical cases
• To reduce mortality & morbidity from vaccine preventable infections

Question 4

What are the non-specific defences of the immune system?

Answer 4

• Skin
• Mucous membrane of gut/lung
• Acid & enzymes in gut
• Metabolism/inactivation

Question 5

What are the components of the innate immune system?

Answer 5

• WBC
• Complement
• Cytokines

Question 6

Describe passive immunity

Answer 6

• Mother to unborn baby
• Blood transfusions
• Disappear after several weeks

Question 7

Describe active immunity

Answer 7

• long-lasting produced by immune system in response to antigens
• Immune system makes antibodies to destroy them
• Vaccination allows active immunity without disease/complications
• Leads to immunologic memory

Question 8

Define antigen & antibody

Answer 8

Antigen= bound to an antibody
Antibody= produced to one specific antigen

Question 9

What is the site of interaction between antigens & antibodies called?

Answer 9

Antigenic determinants or epitopes

Question 10

What types of antibodies are there?

Answer 10

I`gM
IgG
IgA
IgE

Question 11

What type of antibodies (immunoglobulins) are released in a primary & secondary immune response?

Answer 11

1= mainly IgM
2= mainly IgG

Question 12

How do antibodies produce immunity?

Answer 12

• Produced from B-lymphocytes
• Binding triggers clonal expansion
• 1st wave= IgM then IgG
• IgG bind to antigen through simultaneous complement binding facilities, destruction of antigen-bearing micro-organism
• Infection resolved levels of IgG decline
• One set of IgG producing B-lymphocytes persist with ability to recognise specific antigen= immunological memory

Question 13

What vaccines given lead to active immunity?

• Live
• Inactivated toxins
• Inactivated organisms
• Components of organisms

Answer 13

• LIVE=MMR, BCG, Yellow fever, Varicella
• IT= Diphtheria, tetanus
• IO= IPV, typhoid, pertussis
• C= influenza, pneumococcal

Question 14

What specific diseases can be protected from by passive immunity?

Answer 14

• Rabies
• Hep B
• Varicella
• Botulism
• Tetanus
• All by injection of human immunoglobulin

Question 15

What are advantages & disadvantages of a live vaccine?

Answer 15

• A= strong immune response, local & systemic immunity, single dose usually sufficient
• D= potential to revert to virulence, contraindications, poor stability, contamination, interference by viruses/vaccines & passive antibody

Question 16

What are advantages & disadvantages of an inactive vaccine?

Answer 16

• A= Stable, constituents clearly defined, unable to cause infection
• D=Several doses, local reactions common, shorter lasting immunity, adjuvant needed

Question 17

Describe the steps in a chain infection?

Answer 17

• Pathogenic organism of sufficient virulence & adequate numbers
• Reservoir/source to allow multiplication
• Mode of exit
• Mode of transmission
• Portal of entry to host
• Susceptible host (non-immune)

Question 18

How can pathogenic organisms be eliminated?

Answer 18

• Environmental/equipment cleaning & decontamination
• Antisepsis
• Antibiotic prophylaxis

Question 19

How can transmission of a pathogen be minimised?

Answer 19

• Hand hygiene
• PPE (aprons, gloves, masks)
• Equipment decontamination (Surgical instruments, bp monitors, stethoscopes)
• Source & protective isolation
• Use of disposable equipment (Syringes, needles)

Question 20

How can entry & exit by a pathogen be eliminated?

Answer 20

• Antisepsis (surgical skin prep)
• Asepsis (insertion & management of invasive devices)
• Air handling (air filtration & laminar flow, +ve pressure ventilated rooms)
• Sharps management
• Patient management (minimise use & duration of invasive devices)

Question 21

What is surveillance?

Answer 21

• Process of gathering info to ensure disease outbreaks are pre-empted or identified early
• Alert organism (organism capable of causing outbreak)
• Alert conditions (conditions caused by organism)
• Infection prevention & control team

Question 22

What decontamination methods are there? Describe them

Answer 22

• Sterilisation= complete killing/removal of all types of micro-organism (bacteria, viruses, fungi, mycobacteria)
• Disinfection= removal/destruction of sufficient numbers of harmful micro-organisms by chemicals, properties must be considered
• Antisepsis-disinfection applied to damaged skin/living tissue

Question 23

What methods of sterilisation are there?

Answer 23

• Heat (moist-autoclave, steam under high pressure or dry-oven controlled temp cycles)
• Chemical (gas or liquid)
• Filtration
• Ionising radiation (for single use disposable equipment)