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Adverse reactions and endotoxin content of polysaccharide vaccines
Insights
Adverse reactions from meningococcal vaccines were studied in 1.5 million children. A pyrogen-like reaction, or fever, was linked to endotoxin levels, prompting a new testing standard to reduce its incidence.
Area of Science:
- Pediatric Infectious Diseases
- Vaccinology
- Immunology
Background:
- Large-scale vaccination campaigns involving millions of children and young adults are crucial for public health.
- Monitoring adverse reactions post-vaccination is essential for ensuring vaccine safety and efficacy.
- Group A meningococcal and Haemophilus influenzae type b vaccines are vital for preventing serious infections in pediatric populations.
Purpose of the Study:
- To analyze adverse reactions following vaccination with group A meningococcal and Haemophilus influenzae type b capsular polysaccharide vaccines.
- To investigate the incidence and characteristics of pyrogen-like reactions in young children.
- To establish a correlation between vaccine endotoxin content and pyrogenic reactions.
Main Methods:
- Analysis of adverse event records from local health personnel and 19,000 special questionnaires.
- Epidemiological assessment of anaphylactic and pyrogen-like reactions in 1.5 million vaccinated individuals.
- Correlation of pyrogen-like reaction frequency with endotoxin levels using Limulus assay and rabbit pyrogen tests.
Main Results:
- The incidence of anaphylactic reactions was 0.8 per 100,000 injections.
- A pyrogen-like reaction (high fever) occurred in 1.8% of young children (3 months-5 years) receiving meningococcal vaccine.
- Pyrogen-like reaction frequency correlated with vaccine endotoxin content and was most common in children under three years.
Conclusions:
- Capsular polysaccharide vaccines should meet a proposed pyrogen test standard of 1 mug polysaccharide per kg rabbit weight.
- Implementing this standard significantly reduced the incidence of high fever to 0.5% in the studied age group.
- This finding supports enhanced quality control for polysaccharide vaccines to minimize pyrogenic side effects.
Abstract:
Adverse reactions occurring when 1.5 million children and young adults were vaccinated with different lots of group A meningococcal and one lot of Haemophilus influenzae type b capsular polysaccharide vaccines were analyzed on the basis of records kept by local health personnel and 19,000 special questionnaires. The incidence of anaphylactic reactions was 0.8 per 100,000 injections. A pyrogen-like reaction--high fever appearing soon after injection and disappearing within six hours--was seen in 1.8% of children 3 months to 5 years old who received the meningococcal vaccine in the first vaccination project. This reaction was most common in children below three years. Its frequency varied with different vaccine lots and was found to be correlated with the endotoxin content of the vaccines estimated by either the limulus assay or by pyrogen test in rabbits. On the basis of these results we propose that capsular polysaccharide vaccines should pass the pyrogen test with a dose of one mug polysaccharide per kg of rabbit weight. With such vaccines, the incidence of high fever was reduced to 0.5% in children of the same age group.