Diphtheria, pertussis, and tetanus serosurvey in Saudi children

Objective: To evaluate immune protection against vaccine-preventable diseases targeted by the Expanded Program of Immunization in Saudi Arabia. Methods: The study was carried out from September 2001 to February 2002. Using multistage sampling techniques, samples were collected from 5 regions of Saudi Arabia and sent for laboratory assay from the following age groups; 50 samples at 12 months, 50 at 6 years, and 100 at 17 years. Sera were assayed for diphtheria, tetanus, and pertussis. Seto neutralization was used for anti-diphtheria antibody assay, while enzyme linked immunoassay was used for anti-tetanus, anti-filament hemoagglutination (anti-FHA), and anti-pertussis titer (anti-PT) antibody assay. Results: This survey showed that 100% of children had protection levels ( >= 0.01 IU/ml) against diphtheria at one year, 100% at 6 years, and 93.7% at 17 years. For tetanus, 95.9% had protection levels ( >= 0.1 IU/ml) at one year, 100% at 6 years, and 98.9% at 17 years. The geometric mean titer (GMT) of anti-FHA is 22 at one year, 29 at 6 years, and 24 IU/ml at 17 years, while the GMT of anti-PT is 36 at one year, 18 at 6 years, and I I IU/ml at 17 years. Conclusion: Children at one, 6, and 17 years are well protected against diphtheria, pertussis, and tetanus.