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Determination of tetanus and diphtheria antitoxin content in dried samples of capillary blood: a convenient method
1Vaccine Department, State Serum Institute, Copenhagen, Denmark.
Insights
Infant vaccination against tetanus and diphtheria was assessed using filter paper blood samples. Results show mean diphtheria antitoxin levels of 0.53 IU/ml and tetanus antitoxin levels of 4.1 IU/ml.
Area of Science:
- Immunology
- Pediatrics
- Public Health
Background:
- Infant vaccination is crucial for preventing infectious diseases.
- Assessing vaccine-induced immunity in young children is essential for public health surveillance.
- Diphtheria and tetanus pose ongoing risks, necessitating robust immune responses.
Purpose of the Study:
- To evaluate the antitoxin levels against diphtheria and tetanus in infants post-vaccination.
- To determine the feasibility of using filter paper blood spots for assessing infant immunity.
- To correlate infant immune response with potential long-term protection levels.
Main Methods:
- Capillary blood samples were collected from 51 healthy 2-year-old infants on filter paper.
- Blood dots were eluted, and serum volume was determined using dot area calculation or albumin measurement.
- Antitoxin concentrations for diphtheria and tetanus were measured using ELISA and in vitro toxin neutralization assays.
Main Results:
- Mean diphtheria antitoxin concentration was 0.53 IU/ml.
- Mean tetanus antitoxin concentration was 4.1 IU/ml.
- Filter paper elution yielded 100% recovery of antitoxin activity, with comparable serum volume determination methods.
Conclusions:
- Low initial immune response to diphtheria vaccination may contribute to suboptimal antitoxin levels in school-aged children.
- A lowered vaccination response to diphtheria might be observed in environments where the disease is declining.
- Filter paper blood spots offer a viable method for assessing infant antitoxin levels for vaccine efficacy studies.
Abstract:
To assess the effect of vaccination of infants against tetanus and diphtheria capillary blood was drawn from 51 randomly selected healthy infants 2 years of age. The blood was applied directly to filter paper. In the laboratory the blood dots were eluted in phosphate buffered saline for 2 h at room temperature yielding 100% recovery of antitoxin activity. Serum volume in the blood dots was determined by calculation of dot area or by measuring albumin content in the eluted samples by means of rocket immunoelectrophoresis. These approaches were found to be equally applicable. Concentration of antitoxin to tetanus and diphtheria was assessed with ELISA and in vitro toxin neutralization assay respectively. Mean diphtheria antitoxin concentration was 0.53 IU/ml, and mean tetanus antitoxin concentration 4.1 IU/ml. Low initial immune response to diphtheria vaccination may be responsible for the risk among school children to have antitoxin concentration below protective level (reported elsewhere). In environments where diphtheria is disappearing a lowered vaccination response may be expected.