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Conjugate vaccines--a breakthrough in vaccine development
1National Public Health Institute, Helsinki, Finland. Helena.Makela@ktl.fi
The Southeast Asian Journal of Tropical Medicine and Public Health
|September 16, 2003
Summary
Conjugate vaccines combining bacterial polysaccharides with protein carriers effectively immunize infants against serious infections like meningitis. These vaccines have dramatically reduced diseases caused by Haemophilus influenzae type b and other bacteria.
Area of Science:
- Bacteriology
- Immunology
- Vaccinology
Background:
- Encapsulated bacteria like Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae type b (Hib) are primary causes of purulent meningitis in infants.
- The bacterial polysaccharide capsule is crucial for virulence, and antibodies against it offer protection.
- Infants cannot produce antibodies to polysaccharides, rendering traditional polysaccharide vaccines ineffective in early life.
Purpose of the Study:
- To explore the development and efficacy of conjugate vaccines for preventing bacterial meningitis in infants.
- To highlight the success of protein-conjugated polysaccharide vaccines in overcoming infant immune unresponsiveness.
Main Methods:
- Development of conjugate vaccines by linking bacterial polysaccharides to protein carriers.
- Clinical trials and national immunization program data analysis for Hib, meningococcal, and pneumococcal conjugate vaccines.
Main Results:
- The Haemophilus influenzae type b (Hib) conjugate vaccine, introduced in 1987, successfully induced antibody production and protection in infants, leading to the near elimination of Hib disease.
- Group C meningococcal and 7-valent pneumococcal conjugate vaccines, available since 2000, demonstrate high efficacy in preventing bacteremic diseases.
- Conjugate vaccines elicit immunologic memory and reduce asymptomatic bacterial carriage, contributing to significant herd immunity.
Conclusions:
- Protein-conjugate technology has revolutionized infant immunization strategies against encapsulated bacterial pathogens.
- Conjugate vaccines are highly effective in preventing severe diseases like meningitis and bacteremia and confer broad public health benefits through herd immunity.