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Serologic evidence of pertussis infection in vaccinated Iranian children
Anahita Sanaei Dashti1, Abdollah Karimi, Reza Arjmand
1Department of Pediatric Infectious Diseases, Pediatric Ward, Pediatric Infections Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran;
Insights
Despite whole cell pertussis vaccination, pertussis-like illnesses are increasing. This study measured anti-pertussis antibodies in vaccinated children, finding elevated IgG and IgA levels in older children, suggesting further investigation into vaccine effectiveness is needed.
Area of Science:
- Immunology
- Pediatrics
- Vaccinology
Background:
- Pertussis (whooping cough) incidence is rising despite widespread whole cell pertussis vaccination.
- Investigating antibody levels in vaccinated children is crucial to understand vaccine-induced immunity.
Purpose of the Study:
- To assess the occurrence of pertussis in vaccinated children by measuring anti-pertussis antibody levels.
- To evaluate the immune response to the whole cell pertussis vaccine in children over time.
Main Methods:
- Cross-sectional study involving 725 vaccinated children aged 2 months to 6 years.
- Blood samples analyzed for anti-pertussis IgG and IgA using ELISA.
- Statistical significance determined by P<0.05.
Main Results:
- Geometric mean IgG titers decreased after 2 months but increased significantly by 72 months of age.
- 12% of 6-year-old children had IgG levels above the cut-off, compared to 1% in infants.
- Positive IgA titers ranged from 5% to 23% across different age groups.
Conclusions:
- A notable percentage of children exhibit high anti-pertussis IgG and positive IgA levels.
- Increased IgG geometric mean titers at 6 years suggest waning immunity or breakthrough infections.
- Further research is necessary to determine the protective efficacy of the current pertussis vaccine.
Background:
It seems that the incidence of pertussis-like illnesses is considerably increasing despite the wide coverage of immunization with the whole cell pertussis vaccine. We aimed to investigate the occurrence of pertussis in vaccinated children by measuring anti-pertussis antibodies.
Methods:
In this cross-sectional study, blood samples were taken from vaccinated children aged 2, 4, 6, 12, 18, and 72 months. Anti-pertussis IgG and IgA were measured by ELISA. P<0.05 was considered significant.
Results:
725 children were enrolled in the study. Geometric mean titers for IgG that showed a slight decease after 2 months of age and increased distinctly in children aged 72 months. The frequency of the individuals whose IgG was above the determined cut-off (derived from mean+2SD) was observed in 1% of the 2, 4, and 6-month-old infants, 6% of the 12 and 18-month-olds and 12% of the 6-year -old children. Positive IgA titers were detected in 5, 9, 6, 23, 11, and 8% of children aged 2, 4, 6, 12, 18, and 72 months, respectively.
Conclusion:
Since a considerable percentage of children had high levels of anti-pertussis IgG antibodies (≥2 SD), positive anti-pertussis IgA, and most importantly an increased level of anti-pertussis IgG geometric mean titer at 6 years of age, further investigations regarding the protection provided by the presently used pertussis vaccine seems necessary.
