immunisation Flashcards
what are the two single most effective medical public health interventions so far?
clean water and vaccination
what are the characteristics of public health interventions?
they are put in place to protect individuals and communities from infection, reflect the NHS and professional quality, proactive measures for well people and have a long history
what milestones occurred in 1796 and 1860s-90s?
in 1796 Edward Jenner innoculated with cowpox virus for protection against smallpox
in the 1860s-90s Louis Pasteur produced vaccines against anthrax, rabies, cholera, diptheria, and chickenpox
what happened in the early 20th century?
toxoid vaccines against diptheria and tetanus following successful inactivation of pathogen with chemicals
when were the first live vaccines developed and how?
post WW2 using cell culture techniques
which infectious disease is now rising again?
measles/mumps
in 2012, 6.6 million under 5s died, what were a large proportion of these caused by and what is this a big cause of?
58% by infectious disease - this is the biggest cause of worldwide pneumococcal infection
how many under 5 deaths could be prevented by routine vaccines?
around 17%
what are the two types of aims that goals use?
programmatic and strategic
what does a strategic aim comprise?
selective protection of the vulnerable, herd immunity using elimination and then eradication
what does the programmatic aim comprise?
to reduce morbidity and mortality from vaccine preventable infections by:
preventing deaths
preventing infection
preventing transmission - secondary cases
preventing clinical cases
prevent cases in a certain age group
why should we immunise?
to prevent individual disease that is life long and not just in children, ideally want to halt carriage and transmission producing herd immunity as a side effect, eliminate to eradicate the disease
what is the operational target?
they are objectives that help to achieve long term goals - they are specific and measurable - in this case will be high coverage to induce herd immunity
what are the mechanisms of protection in an individual?
the non specific defences, innate immunity and the immune system
what comprises non specific defences?
unbroken skin, mucous membranes of the lung and gut, acid or enzymes of the gut and non specific metabolism or inactivation
what comprises innate immunity?
complement system, cytokines and WBC
what comprises the immune system?
initially the non specific immunoglobulins, the learned specific IgG response and then laying down the immune memory
what is an example of passive immunity?
transfer from mother to baby
how do maternal antibodies work?
they protect the baby for up to a year against illnesses to which the mother is immune
what is a second example of passive immunity?
immunoglobulin can be administered to someone who needs ABs because it contains antibodies pooled together from different donors
how effective is immunoglobulin transplant?
it is effective but is only for a few weeks or months before it disappears
what do most transfused bloods contain?
ABs
what is active immunity?
it is usually long lasting immunity produce by the body’s immune system in response to antigens
where are the antigens in active immunity from?
from infection or vaccination
what does the immune system do in response to antigens?
it produces complementary antibodies
what is a benefit of vaccination over infection for immunity?
the active immunity occurs without the disease or the complications of the disease
what is immunologic memory?
the persistence of protection for many years after natural infection or vaccination
what forms the immune response?
the interaction between the antibody and the antigen
what is an antigen?
it is anything that can be bound by an antibody
what do ABs interact with?
a relatively small part of the antigen molecule. This is known as the antigenic determinants or the epitopes
what does complementary mean with regards to ABs?
ABs are produced to one specific antigen
how many different types of antibody are there?
5
IgG, IgM, IgA, IgE, IgD
what is the primary immune response?
it is the response that develops in the weeks following the first exposure to an antigen and is mainly the IgM antibody
what is the secondary immune response?
it is the response that is faster and more powerful after exposure - it is learnt
it is mainly IgG
where do antibodies originate from?
B lymphocytes
where does the antigen originally bind in first exposure?
non specifically binds to the variable region of the antibody molecules which triggers clonal expansion
what are the first ABs to be produced following the clonal expansion trigger?
IgM followed by IgG
what does IgG do?
it binds tightly to the antigen and then facilitates the destruction of the antigen bearing microorganism
what aids the IgG?
the simultaneous complement binding
what happens once the infection is resolved?
the levels of IgG decline
what is a secondary response to infection?
one set of the IgG producing B lymphocytes persist with the ability to recognise the same antigen again - immunological memory
how can active immunity be induced?
natural infection or inactivated or attenuated live organisms
how can passive immunity be induced?
vertical transmission of autoantibodies from mother to foetus and through breast feeding and injection of human immunoglobulin
for active immunity what are live vaccines?
they act like the natural infection and are MMR, BCG, varicella and yellow fever
for active immunity, what are inactivated organisms, components of organisms and inactivated toxins examples?
inactivated organisms - pertussis, typhoid, IPV
inactivated toxins - diptheria and tetanus
components of organisms - influenza and pneumococcal
for human immunoglobulin injections, what is HNIG?
pooled plasma
for human immunoglobulin injections, what are specific ones?
tetanus, botulism, hep B, rabies and varicella
what are advantages of live vaccines?
single dose is often sufficient to produce long lasting immunity as a strong immune response is evoked and local and systemic immunity are produced
what are disadvantages of live vaccines?
there is potential to revert to virulence, contraindications in the immunosupressed, interference by viruses, vaccines or passive antibodies, poor stability and potential for contamination
what are advantages for inactivated vaccines?
they are stable, the constituents are clearly defined and they cannot cause infection
what are disadvantages of inactivated vaccines?
shorter lasting immunity, multiple doses, adjuvant needed - keep vaccine at injection site and activate the APCs and local reactions are common
what is an adjuvant?
it is a pharmaceutical that modifies the effect of another agent
what types of reactions are there?
local and general
what are the symptoms for a local reaction?
red, pain and swelling and small nodules at the site
what are the symptoms for a general reaction?
fever, loss of appetite, headache, malaise, irritability, fatigue, nausea, vomiting, diarrhoea
why may reactions decrease with more live virus dose?
the antibody produced in response to the live vaccine will neutralise the small amount of vaccine virus in subsequent doses
why may reactions increase with more live virus dose?
if the antibody doses are good from an earlier vaccination then the antibody will bind to the vaccine antigen in a subsequent dose leading to an inflammatory response
when do reactions occur after inactivated vaccines?
around 48hours after
when do reactions occur for live vaccines?
it depends according to the time taken for a virus to replicate
what are the reaction timescales for the live MMR virus?
reaction to the measles component will be malaise, fever and rash that tend to occur in the first week following vaccination
reaction to the rubella part will be joint pain, stiffness or swelling that tend to occur in the second week following vaccination
reaction to the mumps part will be parotid swelling and they tend to occur in the third week but can occur up to six weeks following the vaccination
what changes have been made to the childhood pneumococcal vaccination?
more serogroups added
