Download Lecture 14 - Harford Community College

Lecture 15
Vaccines
History
• 1717- Turkey- smallpox from sick person
into veins of well person
• Variolation- mortality rate- 1%
• Edward Jenner received this treatment at
age of 8
Edward Jenner
• Observed milkmaids who became infected
with cowpox, did not get smallpox
• Experiments- inoculated people with
cowpox in order to prevent smallpox
infection
• Vaccination: Vacca=cow
• Vaccine=
• Smallpox eliminated worldwide
Vaccines
• Prevention can control many
communicable diseases
• Bacterial diseases can often be treated
with antibiotics, if prevention fails
• Viral diseases, not easily treated
• Vaccination only feasible means of
controlling viral diseases
• Herd immunity=
Types of Vaccines
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2.
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4.
5.
6.
7.
Live attenuated vaccines
Inactivated vaccines
Toxoid vaccines
Subunit vaccines
Conjugate vaccines
DNA vaccines
Recombinant vector vaccines
Attenuated whole-agent vaccine
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Use living, but weakened microbes
More closely mimic an actual infection
generally life-long immunity
95% effective for many vaccines
Inactivated whole-agent vaccine
• Use microbes that have been killed
• Still provokes immune response
Toxoid vaccine
• Inactivated toxins
• Remember- toxins are produced by some
bacteria and these are what cause the
disease
Subunit vaccine
• Use only the part of the antigen that
stimulates a strong immune response
• Safer- can not reproduce in the recipient
• Also, little or no extraneous material, and
therefore less side effects
Conjugate vaccine
• Some types of vaccines use
polysaccharides
• Child’s immune system do not respond
well to polysaccharides until 15-24 months
• Polysaccharides combined with another
protein to make vaccine
Nucleic acid vaccines
• Depend on ability of some cells to:
– take up and translate foreign DNA
– display the resulting proteins, inducing a
strong immune response
• One has been approved for humans
Development of new vaccines
• Vaccines most desirable method of disease
control
• Early successful vaccines cultured in animals
• With cell culture- could make vaccines that
would not grow on anything but human cells
• Some vaccines do not need cell culturerecombinant vaccines and DNA vaccines
• Plant potential source for vaccines
• In future- possibility for vaccines to treat
addiction, Alzheimer's, disease and cancer
Safety of vaccines
• Sometimes possibly to cause the disease
while trying to prevent it
• Risk considered worthwhile
• Public reactions to such risks has changed
• Some believe connection between autism
and MMR vaccine
• No studies have shown evidence of this