Vaccines Flashcards
What is adaptive immunity?
- Protection develops more slowly (days)
- Developed by individual only after specific challenge (antigen)
- Effective only against the specific antigen
- Has enhanced ability to deal with recurring antigen (memory)
What is innate immunity?
- Basic resistance to disease (immunity) that an individual is born with (innate)
- Immediate protection against microbes
- Response in place before foreign challenge (antigen) present
- Same response regardless of antigen (non-specific) or previous exposure (no memory)
What are the phases of adaptive immune responses?
1st exposure to antigen leads to development of a primary immune response with proliferation of activated B cells and T cells into effector cells and some to memory B cells and T cells
How is memory from adaptive immunity formed through vaccination programme?
1st exposure to antigen A memory –> 2nd exposure to antigen A produces higher AB concentration –> greater and faster immune response
Vaccine is what form of immunisation?
Active immunisation
Vaccines contain antigen that stimulate an immune response and result in immunologic memory
What is live (attentuated) vaccines?
A virus is weakened, often by repeatedly passing it through a tissue culture in which it replicates poorly
What is the advantages and disadvantages of (attentuated) vaccines?
+ Activates T cells
+ 1/2 doses can provide lifelong immunity
- Must be refrigerated
- Less safe for ppl with weakened immune system
Examples of live (attentuated) vaccines?
MMR
Varicella
Rotavirus
What are some precautions we need to take note for live vaccines?
- Avoid in preg women
- not given in infancy
- Avoid in severely immunocompromised pts –> Haematologic (blood cancer) /solid organ malignancies; Immunosuppressive meds; chemo; HIV with CD4 < 200
- Avoid giving another live vaccine within 28 days
- Spaced 3-10 months apart from adm of AB containing products e.g. immunoglobulins, blood transfusion
What is an inactivated vaccine?
- Whole, killed
- pathogen treated w heat/ chemicals to kill it before it is introduced into the body
What are the + and - of inactivated vaccines?
+ easy to store and transport
+ low risk of causing an infection
- elicits weaker immune response
- may require several doses and boosters
What are examples of inactivated vaccines?
Polio, Hep A, rabies
What is a subunit vaccine?
Portein or polysacc or conjugated
One or more parts of the pathogen, are isolated and used to evoke an immune response
What are the + and - of subunit vaccines?
+ low risk of adv rxn
+ used in ppl w weakened immune systems
- difficult to manufacture
- may require boosters
What are the examples of subunit vaccines?
Hep B, Influenza, pertussis, Pneumococcus
What are Toxoid vaccines?
Toxin produced by pathogen instead of he pathogen itself, is deactivated and used to produce the immune response
What are the + and - of toxoid vaccines?
+ unable to cause disease or to spread
+ stable, easy to distribute
- may require boosters to maintain immunity
Examples of toxoid vaccines?
Diphtheria, tetanus
What is recombinant vaccine?
Use genetic engineering
Contain no actual virus
may contain a modified strain of the virus e.g. live oral typhoid
What are examples of recombinant vaccines?
Hep B, HPV
What are the common route of transmission of viruses?
Respiratory, food and water, vector-borne, blood and body fluids, contact
What are the vaccines for respiratory?
Influenza, pneumococcus, Meningococcus Diphtheria, pertussis Haemophilus influenzae Measles, mumps, rubella Chickenpox BCG (TB)
What are the vaccines for food and water?
Hep A, typhoid, cholera,
Rotavirus
What are vaccines for vector-borne?
Yellow fever, Japenese Encephalitis
Dengue
In development: malaria
What are some vaccines for contact (bites, cuts)?
Tetanus
Rabies
Shingles
What is herd immunity?
- When no one is immunised and an outbreak occurs, spreading throughout community
- when some pop is immunised, it is not enough to prevent the spread of an outbreak.
- Enough pop immunised to contain spread of disease, and most community members are protected, including the unimmunised individuals.
What is the diff btw primary and booster doses?
Primary dose: single/few doses (primary priming series). Some vacc are effective after pri dose, but may need to adm multiple times to induce adequate immunity
Because AB conc wane over time, booster dose (add dose of vaccine) may be required to maintain protective levels of AB
What are the vaccines compulsory in the National Childhood Immunisation Schedule?
- Bacillus Calmette-Guerin (BCG)
- Hep B
- Diphtheria, tetanus, acellular pertussis (paediatric) (DTaP)
- Tetanus, reduced diphtheria and acellular pertussis (Tdap)
- Inactivated poliovirus (IPV)
- Haemophilus influenzae type b (Hib)
- Pneumococcal conjugate (PCV10/ PCV13)
- Pneumococcal polysaccharide (PPSV23) (specific medical condition only)
- Measles, mumps, rubella (MMR)
- Varicella (VAR)
- HPV 2 or HPV4
- Influenza (INF)
What are the vaccines compulsory in the National Adult Immunisation Schedule?
- Influenza (INF)
- PCV13
- PPSV23
- Tdap
- HPV 2 or HPV4\
- HepB
- MMR
- VAR
the last 3 is compulsory for healthcare workers
How does the effectiveness vary by vaccines?
- HepB is 95% effective; 5% non-responder rate
- Varicella has 90% effectiveness
- Several other factors that reduce vaccine effectiveness:
~ Site vaccine given (Hep A/B IM in deltoid, no gluteus)
~ Pt age and immune status (influenza less effective in 80 vs 60)
~ Cold chain problems (not kept at recommended temp)
What are the adv effects of vaccines?
- Mild & common: Pain at injection site, HA, myalgia
- Uncommon: Fever, haemotoma (swelling with blood)
- Severe but rate: Anaphylaxis, hypersensitivity
What are some contraindications and precautions we need to take note for vaccines use?
- Reasons why this patient should not get this vaccine at this time
- Allergy to vaccine or components
- Moderate/severe illness (fever > 38C)
- Bleeding risk (on anti‐coagulation or low platelet counts) ‐ precaution
- Pregnancy (live vaccines)
- Immunocompromise (live vaccines)
What are some general considerations for simultaneous adm of vaccines?
- Most vacc can adm simul/ within same day w/o reducing efficacy or inc adv effects
- Exception: PCV (pneumococcal conj vacc) and Meningococcal conjugate vaccines in pts w functional or anatomical asplenia (not good working spleen) –> for these pts, 4 wk interval btw adm of the 2 vaccines to avoid interference of the MCV with PCV
- Live vaccines adm via IM/SC to be spaced 28 days apart
- Missed doses - dose should be given as
soon as is possible. In most cases, additional doses are not required.
What are the common components of Vaccines?
- Active components
- Adjuvants
- Abx
- stabilisers
- preservatives
- trace components
What are active components?
Form of bac/virus/toxin that causes the disease is used as the antigen
antigen modified so it no longer cause disease, but still elicits immune response from body
can be treated with specific chemicals, so it won’t replicate
can be treated so it doesnt cause serious disease
or only parts of disease-causing agent that dont cause serious smx can be used
What are adjuvants?
Enhances the body’s immune response to the vaccine
thought to help keep antigens near site of injection
they can be easily accessed by immune system cells
no evidence for serious adv effects from adjuvants, though they can cause some minor rxn near the injection site
What are Abx?
Used in the manufacturing process
Prevent bac contamination
They are later removed, and only residual qty remain in vaccine after production process
What are stabilisers?
- vaccines need to be storable
- to ensure various components remain stable and effective
- either inorganic Mg salts (MgSO4, MgCl2, or mixtures of lactose, sorbitol, and gelatin; Monosodium glutamate and glycine also used in some cases)
What are preservatives?
Prevent contamination of vaccines
In multi-dose vaccines
e.g. thiomersal
What are trace components?
left-over from vaccine production process
they are purposeful removed by some amts remain
e.g. Formaldehyde used to deactivate viruses and detoxify bac, but amt remaining is several 100x times lower than the smallest amt known to cause harm in humans
Vaccines for blood & body fluids (sexual, mother-to-child)?
Hep B, HPV
