Effects of 10-valent pneumococcal conjugate (PCV10) vaccination on the nasopharyngeal microbiome

Pathogenic bacteria, such as Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae and Moraxella catarrhalis, are important vaccine targets. The 10-valent pneumococcal conjugate vaccine (PCV10) acts on 10 differents S. pneumoniae serovars. However, this vaccine could also act on other bacteria genera, leading to dysbiosis. Moreover, the vaccination has also been associated with imbalances in the ratio between commensal and potentially pathogenic bacteria. Despite the wealth of studies assessing the influence of the microbiome on vaccine effects, how vaccination can influence the microbiome remains poorly understood. Herein, we assessed the effects of PCV10 on infant nasopharyngeal microbiome composition. Nasopharyngeal aspirates were collected from children with acute respiratory infection (ARI) aged 6-23 months. Two groups were composed of 48 vaccinated and 36 unvaccinated subjects. 16S ribosomal RNA sequencing was performed to assess bacterial composition and results were analyzed with QIIME. Similar bacterial compositions were observed in the unvaccinated and vaccinated samples. Principal component analysis also indicated a similar bacterial composition between the groups. In addition, bacterial diversity was not different between the vaccinated and unvaccinated samples. Accordingly, our results suggest that PCV10 vaccination promotes a specific response against its targets, thereby preserving the nosocomial microbiome. Although not statistically significant, Streptococcus and Haemophilus genera were increased in the vaccinated group, while Moraxella was decreased. Increases in Streptococcus may be associated with vaccine-target taxa replacement by non-pathogenic species. In sum, we observed that PCV10 vaccination acts by promoting a target-specific action against pathogenic bacteria and also induces commensal bacteria colonization without substantially changing the nasopharyngeal microbiome.