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. 2024 Oct 3;42(23):126238.
doi: 10.1016/j.vaccine.2024.126238. Epub 2024 Aug 20.

Pneumococcal carriage and changes in serotype distribution post- PCV13 introduction in children in Matiari, Pakistan

Izn Iqbal  1 , Shahira Shahid  1 , Samiah Kanwar  1 , Furqan Kabir  2 , Fayaz Umrani  3 , Sheraz Ahmed  3 , Waqasuddin Khan  1 , Muhammad Farrukh Qazi  1 , Fatima Aziz  2 , Sahrish Muneer  2 , Adil Kalam  2 , Aneeta Hotwani  2 , Junaid Mehmood  1 , Abdul Khalique Qureshi  3 , Zahra Hasan  4 , Sadia Shakoor  4 , Shaper Mirza  5 , Lesley McGee  6 , Stephanie W Lo  7 , Narender Kumar  7 , Iqbal Azam  1 , Stephen D Bentley  7 , Fyezah Jehan  1 , Muhammad Imran Nisar  8
Affiliations

Pneumococcal carriage and changes in serotype distribution post- PCV13 introduction in children in Matiari, Pakistan

Izn Iqbal et al. Vaccine. .

Abstract

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.

Keywords: Bacterial genomics; Genomic epidemiology; Pneumococcal carriage; Pneumococcal conjugate vaccine; Streptococcus pneumoniae.

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Conflict of interest statement

Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Fig. 1
Fig. 1
Flowchart describing study population.
Fig. 2
Fig. 2
GPSC distribution with associated serotypes in carriage isolates from the post-PCV13 period (2022) in Pakistan (N = 140). PEN: Penicillin, CHL: Chloramphenicol, ERY: Erythromycin, TET: Tetracycline, COT: Cotrimoxazole.
Fig. 3
Fig. 3
Population structure, serotype and resistance profile of carriage isolates from Pakistan. I: intermediate, R: resistant and S: susceptible.
See this image and copyright information in PMC

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