Decline in pneumococcal nasopharyngeal carriage in children 6–23 months with respiratory illnesses following pneumococcal conjugate vaccine implementation

• Published in: Vaccine Vol. 39; no. 40; pp. 5757 - 5761
• Main Authors: Kotler, Leore, Greenberg, David, Givon-Lavi, Noga, van der Beek, Bart Adriaan, Dagan, Ron, Ben-Shimol, Shalom
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 24.09.2021; Elsevier Limited
• Subjects: Age; Alveoli; Antibiotics; Children; Colonization; Conjugates; Hospitals; Infectious diseases; Mathematical analysis; Nasopharyngeal carriage; Pediatrics; Pneumococcal conjugated vaccine (PCV); Pneumonia; Population; Radiography; Respiratory diseases; Seasonal variations; Serotypes; Streptococcus infections; Streptococcus pneumoniae; Trends; Vaccines; Viral infections; Israel; Pneumococcal conjugated vaccine (PCV); PCV; LRI; Nasopharyngeal carriage; Streptococcus pneumoniae; CAAP; NIP; MCHC; Children; PER; IPD; Colonization; OM; VT; SUMC
• ISSN: 0264-410X; 1873-2518
• DOI: 10.1016/j.vaccine.2021.08.082

•We compared pneumococcal carriage in children 6–23 m in late vs. early PCV periods.•Overall carriage rates declined by 35% in community-acquired pneumonia.•In other respiratory diseases, overall carriage rates declined by 22%.•In contrast, rates were stable during the study in healthy/non-respiratory children.•These differences allude to pneumococcal serotypes’ variable disease potential. Following pneumococcal conjugate vaccines (PCVs) implementation, worldwide, pneumococcal carriage rates remained stable, indicating full replacement of vaccine-serotypes (VT) with non-VT. However, data are scarce regarding PCV impact on pneumococcal carriage rates in healthy vs. sick children. We assessed pneumococcal carriage rates dynamics in healthy and sick children 6–23 months, following PCV introduction. This is a prospective, population-based surveillance conducted during the years 2009–2017, in southern Israel. Three groups were defined as follows: Children without respiratory infection signs (the healthy/non-respiratory group); Children who had a chest radiography at the hospital (the Hosp-CXR group); and children with community-acquired alveolar pneumonia (CAAP). Rate ratios (RRs; 95% CI) were calculated, comparing between late-13-valent PCV (PCV13) period (2016–2017) and early-PCV period (2009–2010). Rate ratios were adjusted for antibiotic administration, seasonality and ethnicity, and separate calculations were performed for 6–11 and 12–23 month old children. Overall, 51% of 8627 nasopharyngeal cultures were positive. In 2009–2010 (early-PCV period), the overall carriage rate was 55%; serotypes included in the PCV13 carriage rates were 28%, 31% and 38% in the healthy/non-respiratory, Hosp-CXR, and CAAP groups, respectively. Overall carriage rates in healthy/non-respiratory episodes were stable (~54%) when comparing between 2016 and 17 and 2009–10 (RR = 0.98; 0.84–1.15). In contrast, rates significantly declined for Hosp-CXR (RR = 0.78; 0.63–0.98) and CAAP (RR = 0.65; 0.47–0.89). These trends were driven by ~ 80% VT reductions, coupled with non-VT increase. Following 7-valent PCV/ PCV13 introduction, pneumococcal carriage rates declined in respiratory diseases, but not in healthy children and children without respiratory infections. These trends suggest that a reduction in pneumococcal carriage rates during respiratory infections indicates a decline in respiratory infections caused by VT, while carriage rates in non-respiratory cases reflect non-VT predominance, that have low disease potential for respiratory disease.