A Variety of Vaccines: A History of Vaccine Development
Summary
TLDRThis Health Care Triage episode explores the history of vaccines, from the first inoculations in the 1700s to modern advancements. It covers the development of various vaccine types, including live attenuated, inactivated, toxoid, subunit, and conjugate vaccines. The script discusses the use of adjuvants to enhance vaccine effectiveness and the shift from using animal tissue to human cell lines in vaccine production. It also highlights the importance of vaccines in eradicating diseases like smallpox and polio.
Takeaways
- π The history of vaccination began with the use of cowpox material to induce smallpox immunity in the late 1700s.
- π¬ The first laboratory-developed vaccine was created by Louis Pasteur in 1879, who discovered the process of weakening cholera bacteria by accident.
- π‘ Various methods were used to weaken viruses and bacteria, including heat treatment, chemical exposure, and the use of formalin.
- 𧬠In 1926, aluminum salts were found to increase the effectiveness of the diphtheria toxoid, leading to the use of adjuvants in vaccines.
- π There are different types of vaccines: live attenuated, inactivated, toxoid, subunit, and conjugate, each with specific methods of inducing immunity.
- π Live attenuated vaccines contain weakened live viruses that cannot cause serious illness but can revert to disease-causing forms.
- π Inactivated vaccines are killed with heat or chemicals and require multiple doses and boosters for effective immunity.
- π¦ Toxoid vaccines target the toxin produced by disease-causing germs, such as diphtheria and tetanus.
- 𧬠Subunit and conjugate vaccines were developed for more targeted immune responses, with the latter improving the effectiveness in young children.
- π Production techniques evolved significantly, including the use of chick embryos and human cell lines for virus cultivation.
- π₯ The first combined vaccine was introduced in 1948, and the first subunit viral vaccine for hepatitis B was developed in 1981.
Q & A
What was the significance of the cowpox material in the history of vaccination?
-The cowpox material was used in the late 1700s to induce smallpox immunity, marking the beginning of the world's first vaccinations.
Who was the scientist responsible for the first laboratory-developed vaccine?
-Louis Pasteur was responsible for the first laboratory-developed vaccine in 1879, which was a cholera vaccine.
How did Louis Pasteur accidentally discover the concept of a weakened vaccine?
-Louis Pasteur discovered the concept when his assistant forgot to inject chickens with a fresh batch of bacteria before a holiday, and the bacteria were weakened by prolonged oxygen exposure.
What is an adjuvant and when were they first discovered?
-An adjuvant is a substance that helps increase the effectiveness of a vaccine. They were first discovered in 1926 when aluminum salts were found to enhance the diphtheria toxoid.
What are the two main types of vaccines mentioned in the script?
-The two main types of vaccines mentioned are live attenuated vaccines, which contain weakened live virus, and inactivated vaccines, which are killed with heat or chemicals.
What is the risk associated with live attenuated vaccines?
-The risk with live attenuated vaccines is that they could potentially revert to the original disease-causing form, although this is known to happen only with the live oral polio vaccine.
How do toxoid vaccines work?
-Toxoid vaccines target the toxin produced by a disease-causing germ. They are used to vaccinate against diseases like diphtheria and tetanus.
What is a subunit vaccine and when was the first one licensed?
-A subunit vaccine includes only the components of a pathogen that stimulate the immune system. The first subunit viral vaccine for hepatitis B was licensed in 1981.
What is recombinant DNA technology in the context of vaccine production?
-Recombinant DNA technology involves joining DNA molecules from two different species to produce a vaccine. The first vaccine based on this technology was a hepatitis B vaccine licensed in 1986.
What is a conjugate vaccine and how does it differ from a pure polysaccharide vaccine?
-A conjugate vaccine links polysaccharides to a carrier protein to create a stronger immune response, including in children. Pure polysaccharide vaccines are less effective in children under two and lack a booster response upon repeated doses.
What is the modern miracle attributed to vaccines?
-Vaccines are considered a modern miracle because they have led to the eradication of smallpox and near-eradication of wild poliovirus, as well as significantly reducing the impact of many other diseases.
Outlines
π The Evolution of Vaccines
This paragraph delves into the history and development of vaccines. It starts with the first vaccinations in the late 1700s using cowpox material to induce immunity against smallpox. The narrative then moves to the first laboratory-developed vaccine in 1879 by Louis Pasteur, who discovered the concept of weakening pathogens to create vaccines. The paragraph explores various methods of vaccine creation, including the use of aluminum salts as adjuvants to enhance vaccine effectiveness. It distinguishes between live attenuated and inactivated vaccines, explaining the processes and implications of each. The paragraph also touches on the use of cell cultures, such as chick embryos and human cells, in vaccine production, and the advent of combined vaccines like the DTaP. The development of the polio vaccine by Jonas Salk and the hepatitis B subunit vaccine are also highlighted, emphasizing the ongoing innovation in vaccine technology.
𧬠Advances in Vaccine Technology
The second paragraph focuses on more recent advancements in vaccine technology. It discusses the creation of the first vaccine based on recombinant DNA technology, which involves joining DNA molecules from different species to produce a vaccine. This technology was used to develop a hepatitis B vaccine that did not require human serum, making it safer and more effective. The paragraph also explains the concept of conjugate vaccines, which improve the immune response, especially in young children, by linking polysaccharides to a carrier protein. The paragraph concludes by emphasizing the continuous innovation in vaccine development and the importance of vaccines in eradicating diseases like smallpox and polio. It also hints at upcoming discussions on the immune system's response to vaccines and the concept of herd immunity.
Mindmap
Keywords
π‘Vaccination
π‘Inoculation
π‘Live Attenuated Vaccines
π‘Inactivated Vaccines
π‘Adjuvants
π‘Toxoid Vaccines
π‘Subunit and Conjugate Vaccines
π‘Recombinant DNA Technology
π‘Viral Cultivation
π‘Combined Vaccines
π‘Viral Eradication
Highlights
The history of vaccination began in the late 1700s with the use of cowpox material for smallpox immunity.
The first laboratory-developed vaccine was created in 1879 by Louis Pasteur for cholera.
Pasteur's discovery of vaccine development was accidental due to his assistant's delay in injecting chickens with fresh bacteria.
The weakened bacteria due to oxygen exposure served as a less deadly but effective antigen.
Other lab-based vaccine advancements included the use of carbolic acid, drying of infected tissue, heat treatment, and formalin.
In 1926, aluminum salts were found to increase the effectiveness of the diphtheria toxoid, now known as adjuvants.
Live attenuated vaccines contain weakened live viruses to induce immunity without causing serious illness.
Inactivated vaccines are not alive and cannot replicate, requiring multiple doses and boosters.
Toxoid vaccines target the toxin produced by disease-causing germs, used for diseases like diphtheria and tetanus.
Subunit and conjugate vaccines were mentioned as a topic for later discussion.
Vaccines like rabies and polio were cultivated in chick embryos to avoid side effects.
The use of human cells in vaccine production began around the 1960s following the detection of simian virus.
The first combined vaccine for diphtheria, tetanus, and pertussis was available in the U.S. in 1948.
Jonas Salk began human trials with the killed poliovirus vaccine in 1952.
The hepatitis B subunit vaccine in 1981 was the first to include only components of a pathogen that stimulate the immune system.
The first vaccine based on recombinant DNA technology was the hepatitis B vaccine licensed in 1986.
Conjugate Hib vaccine in 1987 linked polysaccharides to a carrier protein for a stronger immune response.
Vaccine innovation continues with ongoing work to create new and better vaccines.
Smallpox was eradicated worldwide by 1980, and wild poliovirus is nearly eradicated.
Vaccination has significantly reduced the impact of many diseases that once caused widespread suffering.
Transcripts
thanks in part to support from the
national institute for healthcare
management foundation
we're spending six episodes on a special
series on vaccines
last week we discussed the history of
inoculation specifically
varialation as a precursor for
vaccination
the history of vaccination is the topic
of this week's health care triage
[Music]
last week we ended with the world's
first vaccinations in the late 1700s
when cowpox material was used to induce
smallpox immunity
after this it was quite a while before
any new vaccines appeared on the scenes
we saw the first
laboratory developed vaccine in 1879
when louis pasteur weakened cholera
bacteria
in the laboratory for use in an
immunization he accidentally discovered
that this was possible
when his assistant forgot to inject
chickens with a fresh batch of bacteria
before a holiday
injecting the chickens instead when he
returned a month later
these chickens survived showing to only
mild symptoms
and later proved to be immune to further
infection pasteur figured out that the
bacteria had been weakened by the
prolonged oxygen exposure
thus creating a less deadly but still
effective antigen
other lab-based vaccine advancements
followed including
the weakening of anthrax bacteria with
carbolic acid
weakening of rabies virus via the drying
of infected nervous system tissue
from rabbits weakening of diphtheria
toxin
and cholera bacteria by heat treatment
and weakening of a measles virus strain
by passing it several times like
40 to 80 times through different cell
types these
and other methods including the use of
formalin a solution of formaldehyde
were experimented with to kill or weaken
viruses toxins and bacteria
in order to create safe and effective
vaccines
in 1926 it was discovered that aluminum
salts could help to increase the
effectiveness of the diphtheria toxoid
we now call such substances adjuvants
and make regular use of them
it might be good to stop here and
explain the different types of vaccines
we'll start with live attenuated and
inactivated vaccines
live attenuated vaccines are made by
weakening the disease-causing virus
meaning it contains live virus to induce
immunity
but in a form that cannot cause serious
illness
we should note that these types of
vaccines could revert to the original
disease causing form
though this is only known to happen with
the live
oral polio vaccine the polio shot
not a live virus inactivated viruses
have been
inactivated with heat or chemicals like
formalin
and are thus not alive and able to
replicate
the response to these vaccines doesn't
resemble natural infection in the way
that live virus responses do
and they often require multiple doses
and then boosters
despite these limitations inactivated
viruses are sometimes necessary
due to limitations of live vaccines such
as their storage temperature needs or
the risk of
live virus exposure in cases of a
weakened immune system there are also
toxoid vaccines which target the toxin
produced by a disease-causing germ
toxoid vaccines are used to vaccinate
against diseases like diphtheria
and tetanus and lastly there are also
subunit
and conjugate vaccines which we'll get
to in a bit production techniques have
also undergone enormous changes over the
years
it was discovered that viruses like
rabies and polio that affect the nervous
system could be cultivated in chick
embryos
which help to avoid major side effects
that result from cultivating a virus
with nervous system tissue
a method was also developed to cultivate
poliovirus and monkey kidney cells
and other viruses in dog and rabbit
kidney cells and in duck embryos
these discoveries also help to reduce
our reliance on using
live animals like monkeys for growing
and testing viruses
however researchers began shifting to
the use of human cells around the 1960s
following the detection of simian virus
and monkey kidney cells
which prompted some concerns though
later research found no relationship
between the presence of that virus
and vaccine complications this does mean
that many vaccines involve the use of
cell lines derived from human fetal
cells
which is a complex and controversial
topic one that would take an
entire episode if not series all on its
own
in 1948 the first combined vaccine
became available in the united states
it combined the diphtheria tetanus and
pertussis vaccines
in 1952 jonas salk began the first human
trials with the killed poliovirus
vaccine
the vaccine was licensed by the us
government when results were announced
in 1955
with 80 to 90 effectiveness against
paralytic polio
1981 we saw the first subunit viral
vaccine for hepatitis b
subunit vaccines include only the
components of a pathogen that stimulate
the immune system
as opposed to including the entire
pathogen these vaccines often require
the use of those
adjuvants i mentioned earlier since they
aren't generally strong enough on their
own
all hpv vaccines licensed in the u.s are
subunit vaccines
using a protein that self-assembles to
form empty shells
that resemble hpv virus-like proteins
and in 1986 a hepatitis b vaccine that
did not use human serum became the first
vaccine based on recombinant dna
technology
which describes the process of joining
dna molecules
from two different species together this
sounds pretty frankenstein
and has thus sometimes been used to
scare people but it's actually pretty
straightforward once you understand what
the process actually entails and
achieves
for this vaccine the process involved
altering yeast cells
so that they produce the viruses antigen
the component of the virus that elicits
an immune response
which in this case was a surface protein
in the virus
this was done by using an enzyme to
remove the surface protein
and then insert the code for that
protein into yeast cells
so they could grow a bunch of it in
order to manufacture the vaccines
it's an incredible feat of technology
it's also safe and effective
in 1987 a conjugate hib vaccine
as opposed to pure polysaccharide
vaccine was licensed
polysaccharides are long chains of sugar
molecules that create an
outer coating on the antigens of certain
bacteria pure polysaccharide vaccines
are able to induce antibodies against
these but
aren't all that effective in children
younger than two because their immature
immune system struggles to recognize the
coded antigens
these vaccines also lack a booster
response upon repeated doses
these issues were resolved with the
development of conjugate vaccines
which linked the polysaccharides to a
carrier protein
an alteration that resulted in a
stronger immune response
including a response in children though
we should note that there are still pure
polysaccharide vaccines available for a
small group of diseases
we could go on and on for days about all
the individual developments advancements
trials and people that have contributed
to vaccines as we know them
but we've done our best to cover the
larger steps as concisely as we could
and we should mention that vaccine
innovation isn't a thing of the past
work is still underway to create new and
better vaccines
for now we'd just like to stress what a
modern miracle the vaccine is
the last cases of naturally occurring
smallpox in the united states happened
in texas in 1949
and no cases of naturally occurring
smallpox have been seen in the world
since 1980.
wild poliovirus is very nearly
eradicated
and many diseases that used to wreak
havoc on the human race have been
brought to heal by vaccination
it's truly a shame the vaccines are
sometimes villainized more than the
horrible diseases they protect us from
next week in the third episode of this
series we'll talk about the landscape in
which the vaccine thrives
the immune system how does it work and
how does it respond to viruses and
vaccines
what's the deal with vaccines and herd
immunity these questions and more
next week we hope to see you there hey
you enjoyed this episode you should
enjoy episode one in the series on the
history of inoculation
you should also watch the playlist of
the whole series we'd also like if you
like the video and subscribe to the
channel down below so you don't miss
anything
and also go on over to patreon.com
healthcare triage where you can help
support the show even during a global
pandemic
we'd like to especially acknowledge our
research associates james glasgow joe
severts josh gister and michael chin
and of course our surgeon admiral sam
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