ABSTRACT
This study examines different factors influencing the 13-valent pneumococcal conjugate vaccine (PCV13) specific antibody response in 8-13 months old Danish children starting in day care. We present secondary findings to the ProbiComp study, which included nose swabs, buccal swabs and blood samples from the children before entering day care (baseline) and again after 6 months. Pneumococci isolated from nose swabs were identified by latex agglutination kit and Quellung reaction. Luminex-based assay was used for antibody measurements against specific anti-pneumococcal capsular IgG. Buccal gene expression was analyzed by qPCR. Statistical analyses were performed in R and included Pearson's Chi-squared test, Welch two sample t-test and linear regression models. The PCV13 antibody response was unaffected by whether the children were carriers or non-carriers of any pneumococcal serotype. Having siblings increased the risk of carrying serotype 21 before day care (p = 0.020), and having siblings increased the PCV13 antibody response at the end of study (p = 0.0135). Hepatitis B-vaccination increased the PCV13 antibody response before day care attendance (p = 0.005). The expression of IL8 and IL1B was higher in children carrying any pneumococcal serotype at baseline compared to non-carriers (p = 0.0125 and p = 0.0268 respectively).
Subject(s)
Antibodies, Bacterial/blood , Carrier State/epidemiology , Pneumococcal Infections/epidemiology , Pneumococcal Vaccines/immunology , Streptococcus pneumoniae/immunology , Antibodies, Bacterial/immunology , Bifidobacterium animalis , Carrier State/blood , Carrier State/microbiology , Carrier State/prevention & control , Child Day Care Centers/statistics & numerical data , Denmark/epidemiology , Female , Hepatitis B Vaccines/administration & dosage , Hepatitis B Vaccines/immunology , Humans , Immunogenicity, Vaccine , Infant , Lacticaseibacillus rhamnosus , Male , Pneumococcal Infections/blood , Pneumococcal Infections/microbiology , Pneumococcal Infections/prevention & control , Pneumococcal Vaccines/administration & dosage , Probiotics/administration & dosage , Risk Factors , Siblings , Streptococcus pneumoniae/isolation & purification , Treatment OutcomeABSTRACT
This study examined the carriage of Streptococcus pneumoniae in healthy Danish children aged 8-19 months and assessed the effect of the probiotics Lactobacillus rhamnosus GG and Bifidobacterium animalis subsp lactis on the pneumococcal carriage during daycare enrolment. Potential risk factors of pneumococcal carriage were analysed and the carriage study was compared with registered invasive pneumococcal disease (IPD) data. This study is a part of the ProbiComp study, which was a double-blind, randomized controlled trial, including 290 children allocated to probiotics or placebo for 6 months and recruited during two autumn seasons (2014/2015). Pneumococci were identified by optochin sensitivity, bile solubility, α-hemolysis and/or capsular reaction. Serotyping was performed by latex agglutination kit and Quellung reaction. The carriage rate of S. pneumoniae was 26.0% at baseline and 67.4% at the end of intervention. No significant difference was observed between the placebo group and the probiotics group (p = 0.508). Children aged 8-19 months were carriers of non-pneumococcal vaccine serotypes causing IPD in children aged 0-4 years. However, serotypes causing most IPD cases in Danish elderly were either not found or found with low prevalence suggesting that children are not the main reservoir of those serotypes and other age groups need to be considered as carriers.
