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in 1796 the scientist Edward Jenner
injected material from a cow pox virus
into an eight-year-old boy with a hunch
that this would provide the protection
needed to save people from deadly
outbreaks of the related smallpox virus
it was a success the eight-year-old was
inoculated against the disease and this
became the first ever vaccine but why
did it work to understand how vaccines
function we need to know how the immune
system defends us against contagious
diseases in the first place when foreign
microbes invade us the immune system
triggers a series of responses in an
attempt to identify and remove them from
our bodies the signs that this immune
response is working are the coughing
sneezing inflammation and fever we
experience which work to trap deter and
rid the body of threatening things like
bacteria these innate immune responses
also trigger our second line of defense
called adaptive immunity special cells
called b-cells and t-cells are recruited
to fight microbes and also record
information about them creating a memory
of what the invaders look like and how
best to fight them this know-how becomes
handy if the same pathogen invades the
body again but despite this smart
response there's still a risk involved
the body takes time to learn how to
respond to pathogens and to build up
these defenses and even then if a body
is too weak or young to fight back when
it's invaded it might face very serious
risk if the pathogen is particularly
severe but what if we could prepare the
body's immune response readying it
before someone even got ill this is
where vaccines come in using the same
principles that the body uses to defend
itself scientists use vaccines to
trigger the body's adaptive immune
system without exposing humans to the
full strength disease this is resulted
in many vaccines which each work
uniquely separated into many different
types
first we have live attenuated vaccines
these are made of the pathogen itself
but a much weaker and tamer version next
we have inactive vaccines in which the
pathogens have been killed the weakening
and inactivation in both types of
vaccine ensures that pathogens don't
develop into the full-blown disease but
just like a disease they trigger an
immune response teaching the body to
recognize an attack by making a profile
of pathogens in preparation the downside
is that live attenuated vaccines can be
difficult to make and because they're
live and quite powerful people with
weaker immune systems can't have them
while inactive vaccines don't create
long lasting immunity another type the
subunit vaccine is only made from one
part of the pathogen called an antigen
the ingredient that actually triggers
the immune response by even further
isolating specific components of
antigens like proteins or
polysaccharides these vaccines can
prompt specific responses scientists are
now building a whole new range of
vaccines called DNA vaccines for this
variety they isolate the very genes that
make the specific antigens the body
needs to trigger its immune response to
specific pathogens when injected into
the human body those genes instruct
cells in the body to make the antigens
this causes a stronger immune response
and prepares the body for any future
threats and because the vaccine only
includes specific genetic material it
doesn't contain any other ingredients
from the rest of the pathogen that could
develop into the disease and harm the
patient if these vaccines become success
we might be able to build more effective
treatments for invasive pathogens in
years to come just like Edward Jenner's
amazing discovery spurred on modern
medicine all those decades ago
continuing the development of vaccines
might even allow us to treat diseases
like HIV malaria or Ebola one day
you
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