with vaccinations - immunisation!
and the 'pros' and 'cons' of vaccination
Doc Brown's Biology exam study revision notes
There are various sections to work through, after 1 they can be read and studied in any order.
Sub-index of notes: Our body's defence mechanisms against infections from
pathogens, help from vaccines & drugs
(8) How can our
health be further protected from pathogens?
with vaccinations - immunisation!
and the 'pros' and 'cons' of vaccination
Be able to explain how the treatment of disease has changed
as a result of increased understanding of the action
of antibiotics and immunity.
is the action of making a person or animal immune to infection,
typically by inoculation with a vaccine.
is a defence against a pathogen by antibody production in the body.
can be gained by pathogen infection or from vaccination.
These procedure aid the function of our immune system.
Be able to evaluate the consequences of mutations of bacteria
and viruses in relation to epidemics and pandemics
- data provided.
Be able to evaluate the advantages and disadvantages of
being vaccinated against a particular disease - data provided.
As already mentioned, Semmelweiss recognised the importance of
hand-washing in the prevention of
spreading some infectious diseases.
By insisting that doctors washed their hands
before examining patients, he greatly reduced the number of deaths from
infectious diseases in his hospital.
Some medicines, including painkillers, help to relieve
the symptoms of infectious disease, but do not kill
As we have seen, our immune system of the body produces specific
antibodies to kill a particular pathogen.
This leads to
immunity from that pathogen.
In some cases, dead
or inactivated pathogens stimulate antibody
If a large proportion of the population
is made immune to a pathogen by vaccination-immunisation, the spread of the
pathogen is very much reduced - which is what the next section is all about
If you become infected with a new
('foreign') pathogen that your immune system doesn't recognise as
'friendly', it takes your white blood cells a few days to produce the
antibodies to protect you.
In the mean time you are
unfortunately ill and not feeling well to a greater (fatal) or lesser
(a bit poorly) degree.
Vaccination is a
successful method to drastically reduce the response time of your
immune system and usually prevents the onset of the disease.
People can be immunised against a disease by
introducing small quantities of dead or inactive forms
of the pathogen into the body (vaccination).
The process of vaccination has
radically changed the way we fight disease because it is not about
treatment of a disease, it is all about preventing the effects of an
Know that vaccination is an
important method of
What is vaccination? What is a vaccine?
What is immunisation?
Vaccination protects the
individual from future infections and mass scale vaccination can greatly
reduce the incidence of disease.
Protection is better than cure!
If you become infected with a pathogen, it takes a few days for your white
cell immune system to deal with the microorganism, and you can become quite
ill in a few days.
Vaccination is the
process of injecting the individual with small amounts of specific harmless
dead/inactive microorganisms (pathogens) which carry the antigens that cause the immune
system to produce the corresponding protective antibodies - even though
the pathogen is in a harmless form.
Different vaccines are
required for specific pathogens e.g. flue, HPV (human papilloma
virus), polio and whooping cough all have their own vaccine.
The MMR vaccine
contains weakened versions of the viruses that cause measles,
mumps and rubella (German measles) and is very effective in
aiding our immune system to fight these pathogen
As well as injection,
MMR vaccines can be taken orally or using a nasal spray.
stimulate the white blood cells to produce antibodies
that destroy the invading 'foreign' pathogens - essentially aiding our immune
This makes the person
immune to future infections by the microorganism ie gives the individual
immunity from further attacks - the overall process is referred to as immunisation.
If the same type of pathogen,
that you have been vaccinated against, enters your body, your body can respond by
rapidly making the correct
antibody, in the same way as if the person had
previously had the disease.
Vaccination is when the
vaccine is administered to you (usually by syringe injection).
Immunisation is what
happens in your body after you have the vaccination.
The vaccine stimulates your
immune system so that it can recognise the disease (invasive
pathogen - bacteria or virus) and protect you from future
infection (i.e. you become immune to the infection).
The diagram and notes below what
happens on vaccination to complete the immunisation effect.
You are injected by vaccination with a weakened/inactive/dead form of the
pathogen - although harmless, your body will respond to the 'new'
antigens detected - an immune response.
Your lymphocyte white blood cells recognise the pathogen as harmful
and produce the antibodies to counteract 'what is perceived' as an
3. If the same
actually active pathogen enters your body, it is quickly recognised
by its antigen molecules and attacked by the specific antibodies
already present and more can be made too, quite rapidly.
4. The effect of
the pathogen is 'neutralised' so you don't become ill.
When the pathogens are combined with the antibodies they are much
more susceptible to be ingested by the phagocyte white blood cells
MMR vaccine is used to
triple protect children against
measles, mumps and rubella (German measles).
The vaccine contains weak
inactive versions of three viruses that cause measles, mumps and rubella.
The effects of vaccination can
'wear off' over time, and booster injections maybe necessary to increase the
levels of the protective antibodies.
The graph above illustrates the
possible sequence of events involving
The body is first vaccinated with a dead or inactive form of the
In the body's primary response, the lymphocytes recognise the antigens
and produce the specific antibodies
to counteract the perceived threat of the form of the pathogen in the
Eventually, the body stops responding to the vaccination, and the
antibody concentration falls, but NOT to zero!
The memory lymphocytes retain the information to recognise the shape of
the antigen if an infection of the same pathogen occurs. The body has
been immunised to
fight this particular pathogen.
If the body becomes re-infected with the same pathogen, the memory lymphocytes immediately
recognise the pathogen antigen and rapidly make lots of the specific
So, the 2nd response of your immune system is faster and
stronger compared to the original vaccination. The immunisation has
The specific antibody reaches a maximum concentration to fight the
As the infection is gradually overcome the antibody concentration falls.
arguments for and against vaccination (the 'pros and cons')
For vaccination - immunisation:
resulted in the large scale control of many infectious diseases that were
once common and often fatal e.g. measles, mumps, polio, rubella, smallpox,
tetanus, whooping cough etc.
These communicable diseases
were once common in the UK but smallpox has been completely
eradicated and polio infections are very rare these days (down
as much as 99%)
Epidemics are less likely with mass vaccination
- spread of the disease is less likely as there are fewer infected people to carry an active form of the disease - but a large percentage of the
population needs to have been vaccinated - less people around to
carry and pass on the pathogen.
This means people who aren't
immunised, are less likely to catch the disease as there are far
less people to pass it on. This situation is known as 'herd
immunity' - lots of people have the antibodies to
combat the pathogen and therefore far less people can be
carriers of the pathogen..
Herd immunity is defined as
the resistance to the spread of a contagious
disease within a population that results if a sufficiently high
proportion of individuals are immune to the disease, especially
through vaccination - in either case, lots of people have
the antibodies to combat the pathogen and therefore far less
people can be carriers of the pathogen..
Without mass vaccination an outbreak of
epidemic proportions is much more likely - many more people potentially to carry
and transmit the disease which can spread rapidly, particularly
in densely populated areas where lots of people are in close
A notes of caution on using
(i) After the two 'shots' of
the MMR vaccine as a child, your protection from measles, mumps
and rubella should last you a lifetime.
(ii) Others, like the
injection for protection against the tetanus bacterium and polio
virus, only give you immunity for about 10 years - so, in many
cases of vaccination, you need booster doses.
(iii) Due to mutations of the
flue virus strains, your immunity lasts a year and you need a
fresh 'flue jab' before every winter - but this is your choice,
highly recommended for older people like me!
(iv) No vaccine has been
developed to protect us from the common cold or the HIV virus.
vaccination - immunisation:
Immunisation programmes are not
always successful - some vaccines do
not always give you immunity.
So, development work goes on all the time to
make more effective vaccines - especially as different strains of viruses
and bacteria are constantly evolving.
There may also be side-effects
in which the 'patient' has a bad reaction to a particular vaccine eg
swelling, fever, seizure (serious!), but such reactions and complications
are rare and the mass good effect of large scale immunisation should be balanced against the very rare negative
effect - however serious this might be.
There are some concerns over
using 'whole' pathogens so that the vaccine actually causes
disease in the person. Therefore some vaccines only use parts of
the pathogen cells which must include the antigens for the white
blood cells to react to.
Producing vaccines and
carrying out mass vaccination programmes can be expensive - the
disease may be rare or the vaccine proves to be not that
The benefits of vaccination
must outweigh the development and production costs involved.
There is a very small risk
involved with most medical treatments
Side-effects, usually minor, are not
uncommon, BUT, without vaccination some of these diseases are fatal or have very
serious non-fatal outcomes - people can die of from measles, rubella has
serious consequences for pregnant women, there can be serious complications
for infected people who have not been vaccinated.
Following a seaside accident -
cut on knee, as
an eleven year old, I collapsed unconscious after a tetanus injection at a
local hospital. I was ok within half an hour BUT my parents got a bit of a
Parents of young children are
always given details of vaccination schedules and where appropriate,
warned of side effects associated with specific vaccines.
Sadly in some countries,
including in the UK, a lot misinformation has been put about on social
media about the supposed ill-effects of taking the MMR (mumps,
measles and rubella) vaccine e.g. causing autism. The information
was not backed up by real scientific data and as a result was
hundreds of thousands of young children were not vaccinated with
three medical conditions with potentially serious consequences.
Know and explain that passive immunity is only a
short-term defence of antibodies against pathogens.
Passive immunity can be acquired from another
individual, e.g. from mother to infant in breast feeding.
However, know that
(i) memory cells are not produced in passive
(ii) BUT, the gaining of passive immunity
is really important for breast-fed infants.
Learning objectives for this section on immunisation
Be able to describe and explain fighting infections
using vaccination and
immunisation e.g. the MMR 'jab'.
Be able to discuss the advantages disadvantages of
immunisation, and that the immunity produced is aiding our immune
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