Rapid replacement by non-vaccine pneumococcal serotypes may mitigate the impact of the pneumococcal conjugate vaccine on nasopharyngeal bacterial ecology

Abstract

There is growing concern that interventions that alter microbial ecology can adversely affect health. We characterised the impact of the seven-valent pneumococcal conjugate vaccine (PCV7) on pneumococcal carriage and the bacterial component of the nasopharyngeal microbiome during infancy. Newborns were recruited into three groups as follows: Group1 (n = 33) was the control group and comprised infants who received PCV7 after 6 months and came from unvaccinated communities. Group 2 (n = 30) came from unvaccinated communities and Group 3 (n = 39) came from vaccinated communities. Both group 2 and 3 received PCV7 at 2, 3 and 4 months. Culture and 16 S rRNA gene sequencing were performed on nasopharyngeal specimens collected at regular intervals from infants. Nasopharyngeal carriage of PCV7 serotypes in Group 1 was significantly higher than in Group 2 and 3 (p < 0.01). However, pneumococcal carriage remained comparable due to an expansion of non-vaccine serotypes in Groups 2 and 3. Determination of phylogenetic dis(similarities) showed that the bacterial community structures were comparable across groups. A mixed effects model showed no difference in community richness (p = 0.15) and Shannon α-diversity (p = 0.48) across the groups. Immediate replacement of pneumococcal vaccine serotypes with non-vaccine serotypes may mitigate the impact of PCV7 on nasopharyngeal bacterial community structure and ecology.

High residual prevalence of vaccine-serotypeStreptococcus pneumoniaecarriage after introduction of a pneumococcal conjugate vaccine in Malawi: a prospective serial cross-sectional study

“…Unlike low-transmission settings, 50 as well as The Gambia 25 and South Africa, 46 we observed a modest increase in NVT carriage among children in Malawi. Given evidence elsewhere of rapid serotype replacement after PCV introduction, it is possible that serotype replacement and redistribution had already occurred before the start of this study, and that as part of a stochastic secular trend, we are now observing an overall decrease in pneumococcal carriage prevalence.…”

“…[22][23][24] In addition, there is evidence of rapid onset of NVT replacement in the region. 25 Thus, it is uncertain whether PCV introduction in sub-Saharan Africa will achieve the sustained control of pneumococcal carriage necessary to effectively interrupt transmission and so disease. This is of particular concern in many sub-Saharan African countries where the 3+0 schedule has been implemented into infant expanded programmes on immunisation (EPI).…”

<p>Serotype Distribution and Antibiotic Susceptibility of <em>Streptococcus pneumoniae</em> Isolates in Tehran, Iran: A Surveillance Study</p>

“…However, serotype replacement was reported even before introducing the first pneumococcal vaccine. 25 The vaccines PCV7, PCV10, and PCV13 covered 52.6%, 52.6%, and 83.7% of the isolates, respectively. The serotypes 19A, 3, and 23F increased during the second period, compared to the first one.…”

Carriage of penicillin-non-susceptible pneumococci among children in northern Tanzania in the 13-valent pneumococcal vaccine era

“…Serotype/group 15B/C has been reported as one of the predominant serotypes/groups recovered after PCV13 introduction in both low-and high-income countries (Devine et al, 2017;Ho et al, 2015;Dube et al, 2018). Other studies in Africa have reported a high prevalence of serotypes/groups 15B/C, 10A, 11, and 19A (Birindwa et al, 2018;Kwambana-Adams et al, 2017;Dube et al, 2018). However, the relatively high prevalence of serotype 19B in this study was unexpected and appears not to have been reported in other recently published African studies.…”