Making Vaccines
Effective Vaccines
• Have low levels of side effects or toxicity.
• Protect against exposure to natural, or wild
forms of the pathogen.
• Should stimulate both an antibody (B-cell)
response and a cell mediated (T-cell) response.
• Have long term, lasting effects that produce
immunological memory.
• Should not require numerous doses or boosters
• Are inexpensive, have a long shelf life and are
easy to administer.
Routes of Administration
• The majority of
vaccines are
administered by
injection
– Subcutaneous
– Intramuscular
– Intradermal
• Oral vaccines are
available for only a
few diseases
Types of Vaccines
• Killed whole cells or inactivated viruses
– Even though they are harmless, they still contain
recognizable antigens on their surface
– Because the microbe does not multiply, larger doses
and more boosters are required.
• Live, attenuated (weakened) cells or viruses
– Vaccines are longer-lasting and require fewer
boosters
– However, the disease agent could mutate back to
pathogenic strain
Types of Vaccines
• Toxoid vaccines
– A purified toxin produced by the antigen is used to
elicit immune response.
• Genetically engineered microbes or microbial
antigens
– Genes for microbial antigens are inserted into a
plasmid vector and are cloned in appropriate hosts.
– The resultant protein product is used to provoke
immune system.
• DNA vaccines
– These vaccines contain all or part of the pathogen
DNA, which is used to “infect” a recipient’s cells.
Herd Immunity
• More individuals that are
immune decreases the
incidence of the disease and
the occurrence of the
pathogen.
• With greater numbers
immunized, it is less likely that
an unimmunized person will
encounter the pathogen.
• Mass vaccination confers
indirect protection for those
who do not receive the
vaccine resulting in “herd
immunity”.