Pneumococcal carriage in young children after introduction of PCV13 in Hong Kong
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Published on: July 25, 2020
Kate Ching Ching Chan1, Reema Subramanian2, Patrick Chong3
1Department of Paediatrics, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong.
Insights
Pneumococcal conjugate vaccine (PCV) use in Hong Kong is associated with reduced carriage rates in young children. However, non-vaccine serotypes, particularly 15 and 6C, are emerging, indicating potential serotype replacement.
Area of Science:
- Pediatrics
- Infectious Diseases
- Vaccinology
Background:
- Pneumococcal conjugate vaccine (PCV) inclusion in Hong Kong's Childhood Immunization Programme since 2009.
- Assessing the impact of 13-valent PCV (PCV13) on nasopharyngeal pneumococcal carriage.
Purpose of the Study:
- Evaluate pneumococcal carriage rates, serotypes, and antimicrobial resistance in young children post-PCV13 introduction.
- Identify factors associated with pneumococcal colonization in infants.
Main Methods:
- Community-based, cross-sectional surveillance study.
- Recruitment of 1541 healthy infants aged 2, 12, and 18 months.
- Nasopharyngeal swab collection, pneumococcal isolate serotyping, and antimicrobial susceptibility testing.
Main Results:
- Overall pneumococcal carriage rate of 5.5%.
- Higher carriage rates in 12- and 18-month-olds; associated with recent respiratory symptoms and siblings under 6.
- Prevalent serogroups/types: 15 (26.2%), 6C (15.5%), 23A (13.1%). Low prevalence of PCV13 serotypes (10.7%).
- High rates of non-susceptibility to erythromycin (79.3%).
Conclusions:
- Low pneumococcal carriage rate observed in Hong Kong children post-PCV introduction.
- Evidence of serotype replacement with a predominance of non-vaccine serotypes, notably serogroup/type 15 and 6C.
- Continued surveillance is crucial to monitor evolving pneumococcal epidemiology and resistance patterns.
Objectives:
Pneumococcal conjugate vaccine (PCV) has been included in Hong Kong's Childhood Immunization Programme since 2009. This study aimed to assess nasopharyngeal pneumococcal carriage rate, serotypes and antimicrobial resistance pattern in young children after the introduction of 13-valent PCV (PCV13).
Study Design:
A community-based, cross-sectional surveillance study was performed on healthy infants attending eleven Maternal and Child Health Centres across different parts of Hong Kong. Nasopharyngeal swabs were obtained from healthy children aged 2, 12 and 18months during their visit to the centers for immunization from June 2013 to June 2014. Pneumococcal isolates were serotyped and tested for antimicrobial resistance. Details of the demographics, family composition, vaccination history and medical history was obtained through interview of the guardians.
Results:
1541 children were recruited. The overall carriage rate was 5.5%. Children aged 12 and 18months were more likely to have pneumococcal colonization (12months OR: 2.88; 95% CI: 1.41-5.87 and 18months OR: 2.19, 95% CI: 1.05-4.57). Recent respiratory symptoms and presence of siblings younger than 6years were independently associated with pneumococcal carriage. Eighty-four pneumococcal isolates were serotyped. The most prevalent serogroup/types were 15 (15B/C, 16.7%; 15A/F, 9.5%), 6C (15.5%) and 23A (13.1%). Overall, 2.4% of the isolates were heptavalent PCV serotypes, 10.7% were PCV13 serotypes and 89.3% were non-PCV13 serotypes. The proportions of penicillin, cefotaxime and erythromycin non-susceptible isolates were 7.3%, 13.4% and 79.3% respectively.
Conclusion:
The rate of pneumococcal carriage was low in young children in Hong Kong and compared to previous local studies there appears to have been an overall reduction in the carriage rate after the introduction of PCV. Likely serotype replacement was noted with a predominance of non-vaccine serotypes in pneumococcal carriage with the emergence of serogroup/type 15 and 6C.
