A longitudinal study of streptococcus pneumoniae carriage in healthy children in the 13-valent pneumococcal conjugate vaccine era.
Few epidemiological data are available after the introduction of the 13-valent pneumococcal vaccine (PCV13) in 2010. We performed repeat nasopharyngeal swabs and evaluated the serotype distribution of Streptococcus pneumoniae (SP) and its association with PCV13 vaccine status in healthy Italian children aged 3-59 months. SP serotypes were assessed by the Quellung reaction. 618 children appropriately (28%) or incompletely (72%) vaccinated for age with PCV13 were available at baseline (T0). 515 were re-evaluated at 6 months from baseline (T6) and 436 at 12 months from baseline (T12). The percentage of appropriately vaccinated subjects at T0, T6 and T12 was 28%, 67% and 92%, respectively. Random effects logistic regression models with robust 95% confidence intervals was used to estimate the time-related changes in SP and PCV13 carriage and marginal probabilities were obtained from such models. The age-corrected probability of SP carriage was 0.31 (95% CI 0.22 - 0.41) at T0, 0.32 (0.24 - 0.40) at T6 and 0.28 (0.20 - 0.35) at T12. The probability of PCV13 serotypes carriage was 0.025 (0.001 - 0.050) at T0, 0.018 (0.001 - 0.039) at T6 and 0.010 (0.001 - 0.023) at T12. A decrease in PCV13 serotypes and a shift in non-PCV13 serotypes colonization was observed. In particular, the 15A serotype accounted for 4%, 8% and 23% of SP isolates at T0, T6 and T12, respectively. In conclusion, the benefits of the PCV13 vaccination on SP carriage increase with increasing coverage rates. The shift of SP isolates toward non-PCV13 serotypes needs to be studied further.
a Department of Pediatrics; Children's Hospital "V. Buzzi" ; University of Milan ; Milan , Italy.
Chiara
C
Mameli
Valentina
V
Fabiano
Laura
L
Daprai
Giorgio
G
Bedogni
Marino
M
Faccini
Maria Laura
ML
Garlaschi
Francesca
F
Penagini
Dario
D
Dilillo
Erminio
E
Torresani
Maria
M
Gramegna
Gian Vincenzo
GV
Zuccotti
D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008137:Longitudinal Studies; D008297:Male; D011008:Pneumococcal Infections / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000627:therapeutic use*; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000276:immunology / Q000472:pathogenicity; D018074:Vaccines, Conjugate / Q000627:therapeutic use*
C538862:13-valent pneumococcal vaccine; D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate
13-valent pneumococcal conjugate vaccine; CI, confidence interval; IPD, invasive pneumococcal disease; MAR, missing at random; N, number; OR, odds ratio; PCV13, pneumococcal 13-valent vaccine; PCV7, pneumococcal 7-valent vaccine; SP, Streptococcus pneumoniae; Streptococcus pneumoniae; VT, vaccine type; children; cohort study; epidemiology; nasopharyngeal carriage