S. pneumoniae transmission according to inclusion in conjugate vaccines: Bayesian analysis of a longitudinal follow-up in schools.
BACKGROUND
Recent trends of pneumococcal colonization in the United States, following the introduction of conjugate vaccination, indicate that non-vaccine serotypes tend to replace vaccine serotypes. The eventual extent of this replacement is however unknown and depends on serotype-specific carriage and transmission characteristics.


METHODS
Here, some of these characteristics were estimated for vaccine and non-vaccine serotypes from the follow-up of 4,488 schoolchildren in France in 2000. A Bayesian approach using Markov chain Monte Carlo data augmentation techniques was used for estimation.


RESULTS
Vaccine and non-vaccine serotypes were found to have similar characteristics: the mean duration of carriage was 23 days (95% credible interval (CI): 21, 25 days) for vaccine serotypes and 22 days (95% CI: 20, 24 days) for non-vaccine serotypes; within a school of size 100, the Secondary Attack Rate was 1.1% (95% CI: 1.0%, 1.2%) for both vaccine and non-vaccine serotypes.


CONCLUSIONS
This study supports that, in 3-6 years old children, no competitive advantage exists for vaccine serotypes compared to non-vaccine serotypes. This is an argument in favour of important serotype replacement. It would be important to validate the result for infants, who are known to be the main reservoir in maintaining transmission. Overall reduction in pathogenicity should also be taken into account in forecasting the future burden of pneumococcal colonization in vaccinated populations.
Cauchemez
Simon
S
INSERM U707, Paris, France. s.cauchemez@imperial.ac.uk
Temime
Laura
L
Valleron
Alain-Jacques
AJ
Varon
Emmanuelle
E
Thomas
Guy
G
Guillemot
Didier
D
Boëlle
Pierre-Yves
PY
D001499:Bayes Theorem; D002353:Carrier State / Q000453:epidemiology / Q000382:microbiology*; D002648:Child; D002675:Child, Preschool; D005602:France / Q000453:epidemiology; D006801:Humans; D008137:Longitudinal Studies; D008432:Mathematical Computing; D008954:Models, Biological; D009960:Oropharynx / Q000382:microbiology*; D011008:Pneumococcal Infections / Q000453:epidemiology / Q000382:microbiology / Q000517:prevention & control / Q000635:transmission*; D022242:Pneumococcal Vaccines / Q000008:administration & dosage*; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification / Q000302:isolation & purification; D018074:Vaccines, Conjugate / Q000008:administration & dosage
D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate