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Pathogen (Target Population)
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Type of Vaccine
|
Clinical Trial Difficulty
|
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Dengue virus
(Infants and children in endemic areas; travelers to endemic areas)
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Attenuated live vector virus containing gene for broadly cross-reacting protective antigen
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Phase I trials must be in adults, in nonendemic areas. Some apprehension over possible enhancement effects for dengue and with new approach
|
|
Escherichia coli
(enterotoxigenic)
(Infants < 6 months)
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A combination of purified colonization factor antigens and possibly other antigens
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Moderate. High attack rate in children and travelers makes evaluation possible in relatively small population. But may need to evaluate protection against certain serotypes or CFA types
|
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Genetically engineered attenuated strains
|
Needs careful monitoring for reversion to virulence
|
|
Hemophilus influenzae type b
(Infants)
|
Conjugated polysaccharide
|
Need to be carried out in very young children
|
|
Hepatitis A virus
(Susceptibles of all ages; routine for preschool children)
|
Attenuated live virus
|
Large number of subjects needed. Initial trials in adults may give false concepts of immunogenicity and reactogenicity for children
|
|
Polypeptide recombinant vaccine produced in yeast
|
Large number of subjects needed
|
|
Hepatitis B virus
(Areas with high perinatal infection: all infants at birth (if possible). Other areas: all infants, simultaneous with other vaccinations, at earliest possible age)
|
Polypeptide produced by recombinant DNA technology
|
Relatively simple
|
|
Japanese encephalitis virus
(Children in epidemic and endemic areas; foreign visitors to epidemic regions)
|
Inactivated virus produced in cell culture
|
Difficult. Low clinical attack rate requires very large number of subjects.
|
|
Mycobacterium leprae
(Immunoprophylactic: all children in endemic areas. Immuno therapeutic: all recently infected individuals)
|
Armadillo-derived M. leprae
|
Low incidence and long incubation period requires many subjects and long time for trials
|
|
Neisseria meningitidis
(Infants, 3 to 6 months)
|
Conjugated capsular polysaccharides, Groups A,C,Y, and W135
|
Difficult because epidemic disease is unpredictable
|
|
Parainfluenza viruses
(Infants)
|
Trivalent, subunit vaccine
(which must contain fusion proteins)
|
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Plasmodium spp.
(All infants at risk, military personnel, travelers)
|
Plasmodium falciparum, synthetic or recombinant sporozoite antigen preparation
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Mosquito challenge to volunteers
|
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Multivalent synthetic or recombinant sporozoite antigen preparation
(P. falciparum, P. vivax, P. ovale, P. malariae)
|
Mosquito challenge to volunteers
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