Comparison of early effects of PCV7, PCV10 and PCV13 on S. pneumoniae (SP) nasopharyngeal carriage in a population based study; the Palestinian-Israeli Collaborative Research (PICR)

BackgroundPneumococcal conjugate vaccines (PCVs), PCV10 and PCV13, are currently used in different countries. We have previously reported the effectiveness of PCV7, following its introduction in Israel and before PCVs were introduced in Palestine. Here, we extended the study and compared the initial impact of PCV10 to that of PCV7/13.\n\nMethodsFour cross-sectional surveys of S. pneumoniae carriage among children <5y through 2009-2014 were preformed among two proximate populations, living under two distinct health authorities, with different vaccination policies. In East-Jerusalem (EJ), PCV7 was implemented in 2009 and replaced by PCV13 in late 2010, while in Palestine (PA), PCV10 was implemented in 2011.\n\nResultsA total of 1267 and 2414 children from EJ and PA were screened. Implementation of both PCV7 (in EJ) and PCV10 (in PA) did not affect overall S. pneumoniae carriage ([~]30%), but resulted in a significant decrease in carriage of VT7 strains. In the pre-vaccine era, VT7/VT13 strains consisted 47.0%/62.0% and 41.2%/54.8% of pneumococci in EJ and PA, respectively. A 48.6% and 53.9% decrease was observed within 3 years of PCV7 implementation in EJ (p= 0.001) and PCV10 in PA (p<0.0001), respectively. These vaccination policies also resulted in [~]50% reduction in VT13-added serotypes especially 6A (from 11.0% to 0.0% (EJ) and 9.5% to 4.9% (PA)). Three years after PCV13 implementation in EJ, an additional 67% decrease in VT13 strains was observed, yet an increase in serotype 3 was observed (0.0% to 3.4%, p=0.056). The prevalence of non-VT13 strains increased during the study period from 38% and 45.3% to 89.8% and 70.7%, in EJ and in PA respectively.\n\nConclusionsWithin the first three years following PCV implementation, we observed similar reductions in carriage of VT10 and VT13 strains with either vaccination policies, with no effect on overall carriage. Further follow-up is needed to compare the long-term effects.