Immunisation & Infection Prevention Flashcards
What are the reasons for immunisation?
- Protects individual & communities
- Proactive measure for well people
- Reflects NHS & professional quality
What are the strategic aims of vaccination?
- Elimination-herd immunity
- Eradication
- Selective protection of the vulnerable
What are the programmatic aims of vaccination?
- Prevents death
- Prevents infection
- Prevents transmission
- Prevents cases in certain age groups
- Prevents clinical cases
- To reduce mortality & morbidity from vaccine preventable infections
What are the non-specific defences of the immune system?
- Skin
- Mucous membrane of gut/lung
- Acid & enzymes in gut
- Metabolism/inactivation
What are the components of the innate immune system?
- WBC
- Complement
- Cytokines
Describe passive immunity
- Mother to unborn baby
- Blood transfusions
- Disappear after several weeks
Describe active immunity
- 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
Define antigen & antibody
Antigen= bound to an antibody Antibody= produced to one specific antigen
What is the site of interaction between antigens & antibodies called?
Antigenic determinants or epitopes
What types of antibodies are there?
I`gM
IgG
IgA
IgE
What type of antibodies (immunoglobulins) are released in a primary & secondary immune response?
1= mainly IgM 2= mainly IgG
How do antibodies produce immunity?
- 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
What vaccines given lead to active immunity?
- Live
- Inactivated toxins
- Inactivated organisms
- Components of organisms
- LIVE=MMR, BCG, Yellow fever, Varicella
- IT= Diphtheria, tetanus
- IO= IPV, typhoid, pertussis
- C= influenza, pneumococcal
What specific diseases can be protected from by passive immunity?
- Rabies
- Hep B
- Varicella
- Botulism
- Tetanus
- All by injection of human immunoglobulin
What are advantages & disadvantages of a live vaccine?
- 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
What are advantages & disadvantages of an inactive vaccine?
- A= Stable, constituents clearly defined, unable to cause infection
- D=Several doses, local reactions common, shorter lasting immunity, adjuvant needed
Describe the steps in a chain infection?
- 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)
How can pathogenic organisms be eliminated?
- Environmental/equipment cleaning & decontamination
- Antisepsis
- Antibiotic prophylaxis
How can transmission of a pathogen be minimised?
- Hand hygiene
- PPE (aprons, gloves, masks)
- Equipment decontamination (Surgical instruments, bp monitors, stethoscopes)
- Source & protective isolation
- Use of disposable equipment (Syringes, needles)
How can entry & exit by a pathogen be eliminated?
- 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)
What is surveillance?
- 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
What decontamination methods are there? Describe them
- 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
What methods of sterilisation are there?
- 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)
