Vaccines Flashcards
What are four requirements to make a good vaccine?
Effective
Safe
Stable
Low cost
Explain why a vaccine needs to be effective and give an example:
Must not only be an adequate immune response but must be the right type of response
e.g a purely antibody response is unlikely to benefit against an infection such as Tb, as T cell mediated immunity is required
Explain why a vaccine needs to have a good duration:
For protection against exposure in the future, the induction of immune memory is essential, may need a boost as can’t rely on and knowledge immunological memory boosted by periodic outbreak
Why will diseases with a longer incubation period be easier to protect against?
The immune system has more time to mount a secondary response
Which type of vaccines induce a stronger and more lasting immunity?
Live vaccines
What are the safety factors of live attenuated vaccines?
- Insufficient attenuation
- Reverse to wildtype
- Admin to immunodeficient patient
- Persistent infection
- Contamination by other viruses
- Foetal damage
What are the safety factors of non-living vaccines?
- Contamination by toxins
- Allergic reactions
- Autoimmunity
What are the safety factor of genetically engineered vaccines?
Possible inclusion of oncogenes
What type of protective antigens should a vaccine contain?
Microbes with artificially reduced virulence (attenuated)
Microbe with naturally reduced virulence
Killed organisms
Sub-cellular fragments
What types of active ingredients are used in a passive vaccination?
Immune serum globulin
Specific immunoglobulins
Monoclonal antibodies
Give an advantage and disadvantage of passive vaccinations:
+ Rapid response
- only give immunity for as long as antibodies are in your body as doesn’t cause an immune response (max 12 months)
What type of active ingredients are used in inactivated vaccinations?
Killed bacterium/virus
Subunit
Toxoid
Peptide or polysaccharide
What type of active ingredients are used in live active vaccinations and why won’t they make you ill?
Attenuated mutants which have lost their virulence
What are the disadvantages of live active vaccines?
Limited host range
Temp sensitive
Cold- adapted
Genetically manipulated
What are passive vaccinations used for?
- prevent disease after exposure
- to ameliorate symptoms of an ongoing disease
- protect immune deficient individuals
- block an action of bacterial toxins and prevent disease
Give three examples of passive vaccinations:
Diptheria, tetanus- prophylaxis+ treatment
Hep A- prophylaxis for travel
Varicells zoster- prophylaxis in imuno deficient
Name two principal methods for how live attenuated vaccines are made:
Serial passage in cells cultured in vivo
Adoption at low temperatures
Describe how a vaccine is made:
Virus grows in monkey kidney cell tissue culture
Repeated sub passage mutations accumulated and non-virulent strains taken
Test in monkeys for paralysis (or neurotoxicity), then clinical trials in humans
Describe three serotypes of polio mutations of attenuated viruses:
Type 1- contains 57 base substitutions
Type 2 and 3- only contain few base substitutions but all but 2 are unrelated
Why are inactivated vaccines used?
When living vaccines aren’t available, for example the reversion to wild type may happen too easily
Give an advantage and disadvantage of inactivated vaccines:
+ Non- infectivity and relatively safe
- Lower immunogenicity so needs several doses
How can sub cellular fractions be used as vaccines?
Protective immunity is directed against a particular part of an organism
What are toxoids?
Bacterial toxins that have been inactivated, usually by formaldehyde, are called toxoids
What is an adjuvant and which type of vaccine does it need to be added to?
Added to vaccines to give a better immune response by enhancing uptake or by stimulating dendritic cells or macrophages
Non- living vaccines
Give an example of an adjuvant
Alum (aluminium hydroxide or aluminium phosphate)
What is a safety factor in live vaccines?
May revert back to virulence (wild- type)
What is the Critical Vaccination Coverage?
The amount of the population that needs to be vaccinated to prevent outbreaks
What type of infection is chemotherapy most effective towards?
Bacteria
Viruses, fungi and parasites are moderate
What type of infection are vaccines most effective towards?
Viruses
Bacteria, fungi and parasites are low/ moderate
What are five factors which would determine whether a global eradication of an infectious disease would be favourable?
- Disease limited to humans
- No long term carrier status
- Cases easily recognisable (so surveillance possible)
- One or two serotypes (single vaccine adequate)
- Stable/ cheap/ effective (more likely to be undertaken)
What are two non- routine immunisations and when will they occur?
Tuberculosis (BCG)- At birth to babies who more likely to come into contact than the general population
HBV- At birth when babies who’s mothers are HBV positive
What is the BCG vaccine?
A vaccine against TB prepared from a strain of the attenuated live bovine TB bacillus
Under which conditions is the HBV vaccine administered?
All pregnant women are given screening for HBV and if they are carriers then the baby will be given the killed vaccine at birth
What is the schedule of the HBV vaccine?
3 doses:
Initial vaccination
Another vaccination after 4 weeks
Another vaccination after 6 months
A booster after 10 years
What is the schedule of the HBV vaccine for babies who’s mothers have HBV?
Initial vaccination within 2 days of birth
2nd dose at 1 month old
3rd dose at 2 months old
Booster and blood test at 12 months old
What is the vaccination effectiveness for the HBV vaccine?
Very effective in patients under 40 years
If older than 40 with first dose may not be as effective
What is the pneumococcus vaccine?
Protects against pneumococcal infection which can cause pneumonia, septicaemia and meningitis, older people are at risk so vaccine is offered to them
What is the virus that causes cervical cancer and how common is it?
Human papilloma virus (HPV)
12th most common women’s cancer
How much protection does the influenza strain give?
70-80%, varies each year and decreases with age, however decreases mortality
What type of viruses are AZT therapy used for?
Retroviruses (HIV)
Who should you not give the measles vaccine to and why?
Pregnant women, risk is almost zero but as a precaution
What are the two forms of the polio vaccination and what are the differences?
Injection not as effective
Oral liquid more effective but 1 in 2.4 million risk of getting polio with it as type 2 and 3 serotypes can reverse back to wild type
What is the difference between the Salk and Sabin vaccine?
Salk- Killed virus, by IV
Sabin- live virus, orally, cheaper
What is the Sabin and Salk vaccination used for?
Polio
