Background: A major constituent of PCV impact on mordibity burden is the indirect protection (herd protection) achieved by reducing nasopharyngeal pneumococcal carrige (NPPnC) in vaccinated individuals. Reduction in NPPnC in older children (who were either non-vaccinated or are several years post-vaccination) is delayed. We studied NPPnC in primary school children 6-10 years old, in an attempt to evaluate this population as a potential reservoir of VT in the community, 5 years post initiation of PCV National Immunization Plan in Israel.
Methods: PCV7 was introduced to Israel National Immunization Plan in Jul 2009 (3 dose regimen: ages 2, 4, 12m) and was gradually replaced by PCV13 from Nov 2010. 2 distinct ethnic populations, Jews and Bedouins, inhabit the region. The latter are of lower socio-economic conditions, with higher crowding and a higher number of children per family. We initiated an ongoing surveillance in primary school children from these two ethnic populations, by obtaining nasopharyngeal cultures 3 times yearly: Fall, winter and spring. Serotypes were determined by the Quellung reaction.
Results: Overall, 3263 cultures were obtained during the 5-year study period in children attending the first 4 years of primary school (Figure 1). From 2010-11 to 2013-14, carriage of PCV13 serotype was reduced by 63% from 15.1% to 5.6% (P<0.001). Carriage of PCV7 serotypes and serotype 6A were reduced by 70% and 84%, respectively (p<0.001 for both); serotypes 1, 5 and 7F (grouped) were reduced by 68% (p=0.07 ); and serotypes 3 and 19A have not yet achieved a reduction. NPPnC rate was lower significantly in Jewish children than in Bedouin children and in children 6-8 years old vs. children 9-10 years old (P<0.001) (Figure 2). The main drastic reduction (81%) from 15.8% to 3.0% (P<0.001) was seen among Bedouin children in PCV7 serotypes + serotype 6A.
Conclusion: A significant reduction in carriage of vaccine serotypes in early school children indicated an important impact of PCV7/13 introduction on circulation of these serotypes in the community. However, 5 years after PCV introduction, early school children still serve as an important vaccine serotype reservoir.
GlaxoSmithKline: Consultant and Speaker's Bureau , Consulting fee and Speaker honorarium
Merck Sharp & Dohme: Consultant , Grant Investigator and Speaker's Bureau , Consulting fee , Research grant and Speaker honorarium
S. Ben-Shimol, None
R. Dagan, Genocea: Consultant and Scientific Advisor , Consulting fee
MeMed: Consultant and Scientific Advisor , Consulting fee
Merck Sharpe and Dohme: Consultant , Grant Investigator and Scientific Advisor , Consulting fee and Research grant
GlaxoSmithKline: Speaker's Bureau , Speaker honorarium
Pfizer: Consultant , Grant Investigator , Scientific Advisor and Speaker's Bureau , Consulting fee , Research grant and Speaker honorarium