paediatric immunisations Flashcards
aim of immunisations
control communicable diseases by:
- preventing onset of disease by primary prevention using pre-exposure
- alter course of disease to prevent or limit its consequences by secondary prevention
how do vaccines work
vaccines teach the immune system to recognise bacteria and viruses before the individual encounters them as potential pathogens which allows the body to fight the pathogens
mechanisms of immunity
- active immunity
- passive immunity
- herd immunity
active immunity refers to
the process of exposing the body to an antigen to generate an adaptive immune response, the response takes days/ weeks but the response tends to be long lasting
Active immunity can be
naturally acquired or acquired by artificial immunisation
antigens are
recognised by the immune system which generates a response resulting in the production of antibodies, the antibodies form antibody-antigen complexes which alerts other immune cells
how are antibodies produced
B cells= humeral immune system, produced in the bone marrow and are triggered to produce antibodies when they encounter a foreign antigen
T cells= cell-mediated immune system, produced in the thymus, CD4 and CD8 T cells which orchestras response of immune system by binding to other cells and sending out signals
passive immunity
process of providing IgG antibodies to protect against infection which gives immediate but short lived protect
passive immunity can be
natural or acquired
natural passive immunity
transplantal transfer, antibodies are transferred to the foetus via the placenta but only protect the neonate for a certain period of time
maternal antibodies protect against
measles, rubella and tetanus but not polio or pertussis
acquired passive immunity
artificially acquired by the transmission of IgG antibodies from another person or animal
types of acquired passive immunity
Hep B, rabies, varicella zoster, diphtheria, botulism
advantages of passive immunity
- rapid action
- can be used post-exposure
- can attenuate an illness
- can control outbreaks
disadvantages of passive immunity
- short term protection
- short term window
- blood derived
- hypersensitivity reaction
- expensive
herd immunity
a form of immunity that occurs when the vaccination of a significant proportion of a population provides a measure of protection to individuals who have not developed immunity
how does herd immunity work
because vaccinated individuals stop the transmission of the organism
what proportion of the population is required to achieve herd immunity
the proportion of the population required to be immune to achieve herd immunity is derived mathematically based on;
- transmissibility and infectiousness of organism
- social mixing of the population
proportion of population required to be vaccinated to achieve herd immunity assumes that
there is no other reservoir of infection (i.e. the infection only affecting humans)
proportion of vaccination required to achieve herd immunity for common diseases
- measles= 90%
- mumps= 75-80%
- smallpox= 80-85%
population immunity to achieve disease eradications is dependant on
Ro which is the basic reproduction rate
what is the basic reproduction rate
a measure of the transmission potential of a disease, i.e. it is the number of secondary infection whick would occur from a typical primary infection in a population that is totally susceptible (i.e. not vaccinated)
vaccines are
a type of active immunity and work by inducing cell mediated immunity responses and serum antibodies
different vaccines induce
different speeds and sustainability of responses
types of vaccines
live attenuated vaccines and inactivated vaccines
live attenuated vaccines
bacteria or virus is modified so the pathogenic factors are removed so the vaccine will not cause the disease however, the body will still mount the sea immune response (i.e. the virus is weakened before administration)
EXAMPLES OF LIVE ATTENUATED VACCINES
oral polio vaccine, measles, mumps, rubella, varicella, rotavirus, flu
inactivated vaccines
microbe is killed therefore, it cannot ever cause the disease which means it is safer than live attenuated vaccine however, it is less effective as the immune response is not as strong so booster vaccinations are usually required
types of inactivated vaccines
- suspensions of killed organisms
- subunit vaccines
- conjugate vaccines
suspensions of killed organisms types of vaccine
whole cell pertussis and whole cell typhoid vaccines
subunits types of vaccines
diphtheria toxic and tetanus toxoid vaccines
conjugate vaccines
polysaccharide attached to immunogenic proteins e,g the Hib and Men C vaccines
contra-indications to vaccination
- confirmed anaphylaxis reaction to previous dose of the same antigen or vaccine component
- live attenuated vaccines in pregnancy, immunocompromised, egg allergy in yellow fever or flu vaccine, severe latex allergy or acute or evolving illness
UK immunisation schedule 2 months
- DTaP/IPV/Hib/Hep B (diptheria, tetanus, pertusis, polio, haemophilus influenza type B, hepatitis B)
- PCV (pneumococcal conjugate vaccine_
- Rotavirus
- Meningitis B
UK immunisation schedule 3 months
- DTaP/ IPV/Hib/ Hep B (second dose)
- Rotavirus (2nd dose)
UK immunisation schedule 4 months
- DTaP/ IPV/Hib/Hep B (3rd dose)
- PCV (2nd dose)
- Meningitis B (2nd dose)
UK imumnisationschedule 12 months
- Hib/Men C (4th dose of Hib, 1st dose of Men C)
- MMR (measles, mumps and rubella)
- PCV (3rd dose)
- Meningitis B (3rd dose)
2-7 years immunisation schedule
Nasal flu spray (annually)
3 years and 4 months immunisation schedule
- preschool booster of DTaP/IPV
- MMR (2nd dose)
12-13 years immunisation schedule
- HPV (human papilloma virus types 16 and 18 2 injections)
14 years immunisation schedule
- Td/IPV booster (Tetanus, diphtheria, polio booster)
- Men ACWY
adults immunisation schedule
- influenza and PPV (penumococal polysaccharide vaccine) for those over 65 and in high risk groups
- DTaP for pregnant woman from 20 weeks gestation
- Shingles vaccine for aged 70
