Comparison of early effects of pneumococcal conjugate vaccines: PCV7, PCV10 and PCV13 on Streptococcus pneumoniae nasopharyngeal carriage in a population based study; The Palestinian-Israeli Collaborative Research (PICR)

Abstract

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.MethodsFour 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.ResultsA total of 1267 and 2414 children from EJ and PA were screened. In 2014, S. pneumoniae was detected in 30.7% and 28.6% of the children in EJ and PA respectively Implementation of both PCV7 (in EJ) and PCV10 (in PA) did not affect overall S. pneumoniae carriage, but resulted in a significant decrease in the prevalence of vaccine-type 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 in VT7 strains 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). While the prevalence of VT13 strains decreased significantly during the study period, the overall carriage rate didn’t change significantly due to replacement with non-VT13 strains which comprised 89.8% and 70.7% of all pneumococci, in EJ and in PA respectively in the last study year.ConclusionsWithin 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.

Effect of a 2+1 schedule of ten-valent versus 13-valent pneumococcal conjugate vaccine on pneumococcal carriage: Results from a randomised controlled trial in Vietnam

“…In Kenya, no effects were found on carriage of 6A or 19A two-years post-introduction of PCV10 [22] . Six-years post-introduction in Kenya there was still no effect on 6A carriage but 19A carriage had increased [23] , similar to findings 1½-2 years post-introduction in Mozambique and three-years post-introduction in Fiji [17] , [24] By contrast in Palestine, at three-years post-introduction of PCV10 there was a decrease in 3/6A/19A carriage driven by 6A, with no change in 19A [25] . It may be that the impact of PCV10 on serotypes 6A and 19A depends on the local pneumococcal epidemiology.…”

Exploring the evidence behind the comparable impact of the pneumococcal conjugate vaccines PHiD-CV and PCV13 on overall pneumococcal disease

“… 17 , 38 , 52 Consequently, PCV7 had no net impact on pneumococcal carriage but its net impact on pneumococcal disease was substantial in many settings. This seeming discrepancy can be explained by a lower virulence of the replacing non-VT compared to VT. 17 , 38 Similar observations have been made for PHiD-CV and PCV13, with both vaccines leading to serotype replacement in carriage 53–57 and disease. 38–40 …”

Impact of Pneumococcal Vaccination in the Nasopharyngeal Carriage of Streptococcus pneumoniae in Healthy Children of the Murcia Region in Spain

“…According to all published studies [ 2 , 22 , 28 ], the percentage of VSs was low at 14.4%, but higher than those observed in other countries [ 4 , 5 , 25 , 26 , 27 ]. It is possible that these variations are related to the level of vaccination in the population, which in our study is not excessively high.…”