vaccinations Flashcards
when is the BCG vaccination given and for what illness?
neonatal
given to children susceptible to TB
when is Hep B given?
first year if born to infected mother
what are the main contra-indications for immunisation?
- Anaphylaxis to a previous dose
- Immunosuppression
- Pregnancy
- Postpone if acutely unwell
Name bogus contra-indications?
Asthma, antibiotics, breast feeding, neonatal jaundice, prematurity, previous history of infection, allergy
what must you do if several live vaccinations are given at the same time?
minimum interval of 3 weeks between them
what diseases dont have a vaccine available to them yet?
malaria, worm infestation, TB, respiratory disease, HIV/AIDS, measles
what is herd immunity?
- The idea that you should vaccinate a certain percentage of a population that will protect the remaining unvaccinated individuals (around 85%).
- Depends on the pathogen, but generally 90% is required for full HI
why may parents not vaccinate their child?
for fear of side effect, judging the risk of vaccine to be higher than the small risk of catching infection
when may herd immunity not work to prevent an infection?
Highly contagious infections like chicken pox, whooping cough and measles
what are features of an effective vaccine?
safety protection longevity neutralising antibodis protective t cells practicality
what considerations should be made when designing a vaccine?
• Whole pathogen or recombinant protein?
o Live attenuated or inactivated vaccine
• Does the vaccine require an adjuvant?
o Injected with vaccine to fool body there is an infection
• Which vaccination route? (Mucosal, injection).
what are you testing when testing a vaccine and what problems may occur?
Reactions to vaccine administration o Anaphylactic reactions o Fever / febrile convulsion o Local reactions o Reversion of live vaccines to ‘wild type’
Problems when pathogen encountered
o Vaccine ineffective
o Heightened immune response to illness
what is a vaccination?
improves quality of immune system to fight against a pathogen in the future
what is an immunisation?
protecting you from a pathogen but only temporarily
what are the types of active immunisation?
- Inactivated – heat-treated
* attenuated – a weaker strain
what are examples of passive immunisation?
receiving antibodies, maternal antibodies from mother to baby
what are modern vaccines?
recombinant peptide vaccines, DNA vaccine, therapeutic vaccines
explain the process of passive immunisation?
- Give injection of killed pathogen
- 10 days later take a blood sample and separate blood cells from serum
- Serum includes neutralizing antibodies
- The serum is then transferred to a different animal
- That animal is then challenged with a live pathogen animal survives
when is passive immunisation given?
given to counteract insect/animal venom
what serum is used usually in passive immunity?
horse serum
what are the problems with passive immunity?
- The immunisation effect lasts for as long as the antibody remains active – a few months at most
- The patient makes an immune response against the serum (can cause “serum sickness”)
what were the 2 types of vaccines or polio?
inactivated vaccine - injected, marinated in formalin, unable to replicate (deactivated)
attenuated vaccine - oral, live weakened polio virus
describe the effects of the inactivated polio vaccine
o Vaccine generates good humoral immunity
o No chance of disease (but often side effects)
describe the effects of the attenuated polio vaccine?
o Virus can replicate but doesn’t usually cause disease
o The vaccine generates humoral and cell-mediated immunity
o However, occasional polio in vaccinated patients.
what is the difference between the inactivated vaccine and attentuated vaccine?
inactivated - needs neutralising antibodies
attenuated vaccines - neutralising antibodies AND cell mediated response
what are the side effects of the MMR vaccine?
malaise, fever, rash (at 1wk), febrile convulsions
what are the contra-indications of the MMR vaccine?
o Acute illness
o Immunosuppression e.g. steroids, AIDS
o Another live vaccine within previous 3 weeks
o Receipt of immunoglobulin within previous 3 months
o Children who have an anaphylactic reaction to egg should be immunised and observed in hospital for 2 hours
what causes diptheria?
Corynebacterium diphtheria
what is the incubation period and pathogenesis of diptheria
Incubation period: 2-5 days
Pathogenesis: disease results from exotoxin-producing strains
what is the cause of pertussis?
Bordetella pertussis
what is the incubation period of pertussis?
7-10 days
what are the adverse reactions to pertussis?
- Local: Redness and swelling
- Systemic: Inconsolable screaming, high fever, hypotonic, seizures, anaphylaxis, bronchospasm
- Encephalopathy (very rare, especially with new vaccine – 1.3/10 million)
what causes tetanus?
Clostridium tetani
what is the incubation period of tetanus?
4-21 days
how is tetanus transmitted?
direct transfer of spores
what does DPT treat?
Diptheria
Pertussis
Tetanus
what are the 2 types of vaccination for hep B?
o Purified from human plasma – HBsAg
o HBsAg produced in yeast cells by recombinant DNA technology
how effective is hep b vaccine?
• Vaccine is 90% effective after a 3-dose series (but this decreases over 40 years of age)
how long does the hepatitis b vaccine last?
• Duration of protection is at least 3-5 years – booster if concentration Antibody <50 IU/I
what is haemophilus influenzae type b?
Encapsulated Gram -ve bacterium – causes bacterial meningitis and epiglottitis in infants and young children
describe the method of making recombinant peptide vaccines
- A specific gene is removed from the pathogen
- Gene is added to a culture of yeast
- A single purified viral protein is used for the vaccine
- Mixed with adjuvant to make the vaccine
how does recombinant peptide vaccine reduce the risk of side effects?
doesnt use the whole pathogen
how do adjuvants work?
- Bias toward Th2 antibody response
- Stimulate mucosal immunity e.g. using pertussis toxin or cholera toxin
- Activate dendritic cells and other APCs
- Bias toward TH1 cell-mediated response (e.g. using IL-12)
how are dna vaccines made?
- A specific gene is isolated from the pathogen
- Gene is placed in a bacterial plasmid vector
- Bacterial DNA acts as an adjuvant (via TLR9)
- Plasmid is injected into the muscle of a recipient
- Viral challenge
- Animal is protected
how do therapeutic vaccines work?
- An animal is already infected and cannot clear the infection e.g. Herpes simplex 2
- Sick animal is vaccinated to BOOST the immune response to the infection
- Animal can now clear the infection
