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Pneumococcal carriage and changes in serotype distribution post- PCV13 introduction in children in Matiari, Pakistan
Izn Iqbal1, Shahira Shahid1, Samiah Kanwar1
1Department of Pediatrics and Child Health, Aga Khan University, Karachi, Pakistan.
Insights
Replacing the 10-valent pneumococcal conjugate vaccine (PCV10) with PCV13 in Pakistan rapidly reduced PCV13 serotype carriage in children. This shift may have increased non-PCV13 serotypes due to vaccine selection pressure.
Area of Science:
- Immunology
- Microbiology
- Public Health
Background:
- Pakistan replaced the 10-valent pneumococcal conjugate vaccine (PCV10) with the 13-valent PCV13 in early 2021.
- The study aimed to assess the impact of PCV13 on nasopharyngeal carriage serotypes in rural Pakistan.
Purpose of the Study:
- To evaluate the effect of PCV13 introduction on pneumococcal serotype distribution in nasopharyngeal carriage.
- To analyze changes in carriage prevalence of vaccine-type and non-vaccine-type pneumococcal serotypes.
Main Methods:
- Children under 2 years were recruited from two rural union councils in Matiari, Sindh, Pakistan.
- Nasopharyngeal swabs were collected, and isolates were processed using whole genome sequencing.
- Vaccination history, clinical, and sociodemographic data were recorded.
Main Results:
- Pneumococcus was detected in 70% of 200 enrolled children; 60.1% received 3 PCV13 doses.
- PCV10 carriage decreased from 13.2% to 7.2%, and additional PCV13 serotypes decreased from 18.5% to 11.4%.
- Non-PCV13 serotypes increased from 68.3% to 81.4%, with significant antimicrobial resistance noted.
Conclusions:
- The replacement of PCV10 with PCV13 led to a rapid decrease in PCV13 serotype carriage among vaccinated children.
- Increased prevalence of non-PCV13 serotypes suggests vaccine-driven selection pressure.
Background:
In early 2021, the 10-valent Pneumococcal conjugate vaccine (PCV10) was replaced with 13-valent (PCV13) by the federal directorate of immunization (FDI), Pakistan. We assessed the impact of a higher valent vaccine, PCV13, on the serotype distribution of nasopharyngeal carriage in rural Pakistan.
Methods:
Children <2 years were randomly selected from two rural union councils of Matiari, Sindh in Pakistan between September-October,2022. Clinical, sociodemographic and vaccination histories were recorded. Nasopharyngeal swabs were collected and processed at Infectious Disease Research Laboratory, Aga Khan University, Karachi. Whole genome sequencing was performed on the culture positive isolates.
Results:
Of the 200 children enrolled, pneumococcus was detected in 140(70 %) isolates. Majority of age-eligible children (60.1 %,110/183) received 3 PCV13 doses. PCV10 carriage declined from 13.2 %(78/590) in 2017/18 to 7.2 % (10/140) in 2022, additional PCV13 serotypes (3, 6A/6C and 19A) decreased from 18.5 %(109/590) to 11.4 %(16/140) while non-PCV13 serotypes increased from 68.3 %(403/590) to 81.4 %(114/140). There were 88.5 %(n = 124), 80.7 %(n = 113), 55.0 %(n = 77), and 46.0 %(n = 65) isolates predicted to be resistant to cotrimoxazole, penicillin(meningitis cut-off), tetracycline, and erythromycin respectively.
Conclusion:
Replacing PCV10 with PCV13 rapidly decreased prevalence of PCV13 carriage among vaccinated children in Matiari, Pakistan. Vaccine-driven selection pressure may have been responsible for the increase of non-PCV13 serotypes.
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