Effects of PCV7 and PCV13 on invasive pneumococcal disease and carriage in Stockholm, Sweden

Abstract

The effects of pneumococcal conjugated vaccines (PCVs) need to be investigated. In Stockholm County, Sweden, PCV7 was introduced in the childhood immunisation programme in 2007 and changed to PCV13 in 2010.Over 90% of all invasive isolates during 2005–2014 (n=2336) and carriage isolates, 260 before and 647 after vaccine introduction, were characterised by serotyping, molecular typing and antibiotic susceptibility, and serotype diversity was calculated. Clinical information was collected for children and adults with invasive pneumococcal disease (IPD).The IPD incidence decreased post-PCV7, but not post-PCV13, in vaccinated children. Beneficial herd effects were seen in older children and adults, but not in the elderly. The herd protection was more pronounced post-PCV7 than post-PCV13. PCV7 serotypes decreased. IPD caused by PCV13 serotypes 3 and 19A increased post-PCV7. Post-PCV13, serotypes 6A and 19A, but not serotype 3, decreased. The serotype distribution changed in carriage and IPD to nonvaccine types, also in nonvaccinated populations. Expansion of non-PCV13 serotypes was largest following PCV13 introduction. Serotype diversity increased and nonvaccine clones emerged, such as CC433 (serotype 22F) in IPD and CC62 (serotype 11A) in carriage. In young children, meningitis, septicaemia and severe rhinosinusitis, but not bacteraemic pneumonia, decreased.Pneumococcal vaccination leads to expansion of new or minor serotypes/clones, also in nonvaccinated populations.

Ten-Year Trends and Clinical Relevance of the Antimicrobial Resistance Genotype in Respiratory Isolates of <b><i>Streptococcus pneumoniae</i></b>

“…In that study, specific serotypes of S. pneumoniae were found to induce respiratory failure more often. More data has been recently published on the trend of skewing of pneumococcal serotypes due to the introduction of new vaccines [15,16,17,18,19]. Unfortunately, our present study was not able to analyze the serotype and it is unclear whether serotype and resistance genotype correlate in inducing respiratory failure.…”

Antimicrobial resistance, penicillin-binding protein sequences, and pilus islet carriage in relation to clonal evolution of Streptococcus pneumoniae serotype 19A in Russia, 2002–2013

“…Being effective in the repulsion of vaccine serotypes from the circulation, vaccination with PCVs is having much broader impact on the microbial community than has been anticipated. In a recent paper by Galanis et al [40], the authors demonstrated that PCV vaccination promoted expansion of new or minor pneumococcal clones and increased clonal diversity not only in vaccinees, but also in nonvaccinated individuals. These findings suggest a possibility of the spread of some serotypes in a PCV-naïve population.…”

Public health impact of pneumococcal conjugate vaccine infant immunization programs: assessment of invasive pneumococcal disease burden and serotype distribution

“…In addition, in countries with high vaccination coverage, VT IPD in older vaccine-ineligible children and adults declined (herd effect), likely due to reduced transmission of VTs [22,24,25]. The effect of PCVs on the overall disease burden has been somewhat attenuated by an increased incidence of IPD caused by non-vaccine serotypes (NVT) after PCV introduction, owing in part to serotype replacement [22,[26][27][28]. Despite the increased incidence of NVT IPD, the impact of PCVs on overall IPD in young children was still substantial [22,29].…”