The effect of immunosuppressive agents on immunogenicity of pneumococcal vaccination: A systematic review and meta-analysis.

INTRODUCTION: Patients with a weakened immune system due to immunosuppressive treatment are at increased risk of infection with Streptococcus pneumoniae. Although pneumococcal vaccination is highly recommended for those patients, the effectiveness of pneumococcal vaccination in this population remains largely unknown. Therefore, the objective of this PROSPERO-registered systematic review and meta-analysis was to evaluate the effect of the most commonly prescribed immunosuppressive agents such as azathioprine, methotrexate, anti-Tumor Necrosis Factor α (TNFα), or rituximab, on the initial serologic response to pneumococcal vaccination in patients with auto-immune disease. METHODS: We included 22 articles comprising 2077 patients, of whom 1623 were treated with immunosuppressive agents, and 454 were controls. RESULTS AND DISCUSSION: The findings of our systematic review indicate that, in patients treated with immunosuppressive medication and compared to controls, the initial serologic response to pneumococcal conjugate vaccine (PCV) and pneumococcal polysaccharide vaccine (PPSV) are impaired. Moreover, this impaired response was more profound after PCV than after PPSV. We hypothesize that the immunosuppressive medication mainly compromises the cellular immunity, explaining the more severely reduced response rate to PCV (which induces a T-cell dependent immune response), compared to PPSV. Treatment with TNFα blocking agents was associated with a more favorable response, compared to patients treated with other immunosuppressive medication. Targeted research applying uniform correlates of protection is needed to bridge the knowledge gap in vaccination immunology in this patient group. PROSPERO registration: CRD42017058364.

Risk factors for carriage of Streptococcus pneumoniae in children.

BACKGROUND: During the past decades Streptococcus pneumoniae has developed significant resistance to many classes of antimicrobial drugs. Potential risk factors for colonization of the nasopharynx by Streptococcus pneumoniae in children and for carriage of drug resistant strains were examined. METHODS: Between 2007 and 2008 nasopharyngeal swabs were collected from 402 children 6 months to 5 years old visiting the public sector immunization centers and outpatient departments as well as offices of paediatricians from private practice in Nicosia district in Cyprus. Information on demographic characteristics and potential risk factors of participating children were collected using a standardized questionnaire distributed to parents. RESULTS: In multivariable analyses we found that attendance at day care center, having siblings in the family and having both parents originating from Cyprus, statistically increased the risk of pneumococcal colonization. Full immunization with PCV7 appears to be a protective factor against colonization by pneumococcus. Previous administration of antimicrobials during the last month prior to specimen collection appeared to be the most consistent risk factor for carrying a non susceptible strain of Streptococcus pneumoniae to either penicillin or erythromycin. Factors such as age, nationality, previous or current breastfeeding, passive exposure to cigarette smoke and attendance in a day care center do not appear as independent risk factors for colonization by non susceptible strains. CONCLUSIONS: Prudent use of antibiotics especially for upper respiratory tract infections in children as well as increased vaccination coverage by the pneumococcal conjugate vaccines could prove effective in reducing levels of colonization by drug resistant pneumococcal strains.

Individual-level effects of antibiotics on colonizing otitis pathogens in the nasopharynx.

BACKGROUND: Although there is evidence of an association between antibiotic consumption and resistant bacteria on a population level, the relationship on an individual level has been less well studied, particularly in terms of nasopharyngeal colonization. We have therefore analysed this association, using data from a closely followed cohort of children taking part in a vaccination trial. METHODS: 109 children with early onset of acute otitis media (AOM) were randomised to heptavalent pneumococcal conjugate vaccine (PCV7) or no vaccination. They were followed for three years with scheduled appointments as well as sick visits. Nasopharyngeal cultures were obtained at all visits. Antibiotic treatments were recorded, as were risk factors for AOM, including siblings, short breast-feeding and parental smoking. Data were entered into a Cox regression model, and the findings of Streptococcus pneumoniae and Haemophilus influenzae with reduced susceptibility to the penicillin group were related to the number of previous courses of antibiotics. RESULTS: There was evidence of an association between the amount of previously consumed betalactams and colonization with beta-lactamasenegative ampicillin-resistant (BLNAR) H. influenzae (RR 1.21; 95% CI 1.03-1.43; p = 0.03), and also with the most commonly prescribed drug; amoxicillin (RR 1.39; 95% CI 1.09-1.76; p = 0.01). There was no evidence for an association between antibiotic consumption and betalactamase producing H. influenzae or S. pneumoniae with reduced susceptibility to penicillin. Furthermore, there was no evidence of an association between resistant bacteria and AOM risk factors or PCV7. CONCLUSION: In this subgroup of children, most of whom were given several courses of antibiotics in early childhood, there was evidence of an association between betalactam/amoxicillin consumption and nasopharyngeal colonization with BLNAR strains, bacteria that have increased in prevalence during the last 10-15 years, and that are notoriously difficult to treat with oral antibiotics.

Recurrent invasive pneumococcal disease in children--host factors and vaccination response.

Streptococcus pneumoniae is still a leading cause of septicaemia, pneumonia and meningitis in young children world-wide with over half a million children dying annually from pneumococcal disease.  Some children are prone to repeated episodes of invasive pneumococcal disease (IPD) because of an underlying predisposing disease. Recurrent IPD (rIPD) is a rarity and published reports on rIPD are limited by having few children included, selected groups of patients or short follow-up periods. Deficiencies in the innate or adaptive immune system have been described in children with rIPD, but the frequency of immunodeficiency among such patients is unknown. The aim of this PhD thesis was to examine paediatric cases of laboratory-confirmed rIPD, over a 33-year period in Denmark, to determine risk factors and study aspects of the immunological background for this problem in children. In October 2007, a seven-valent pneumococcal conjugate vaccine (PCV7) was implemented in the Danish infant immunization programme. An additional aim of the thesis was to examine the impact of vaccination on a population level, following the first three years of general PCV7 vaccination in Denmark. The thesis consists of three papers, which are all directly or indirectly based on data retrieved from the National Streptococcus Pneumoniae Registry. This registry is nationwide and dates back to 1938. The registry contains data from all laboratory-confirmed cases of IPD in Denmark and is continually updated for national surveillance. In Paper 1, we conducted a 33-year retrospective nationwide study of paediatric rIPD. By using data from the National Streptococcus Pneumoniae Registry combined with clinical data from hospital records, we could describe one of the largest known cohorts of children (n:59) with rIPD . We covered epidemiological, microbiological, and clinical features of this clinical entity. Of all children experiencing rIPD, 47% had a known predisposing underlying disease at the time of the rIPD. Most common was immune deficiency due to transplantation. In 19% the episode of rIPD was the clinical manifestation that subsequently led to a diagnosis of an underlying disease. Finally, in 31% of the children no underlying disease was detected. Paper 2 covers data from a follow-up of the cohort of children described in Paper 1. Of this unselected cohort of rIPD, all children without an obvious underlying disease predisposing to pneumococcal disease (such as malignancy, HIV or cerebrospinal-fluid leakage) were invited to participate in the study by undergoing a thorough immunological evaluation. Basic immunological parameters including activity of complement-pathways and T-, B-, NK-cell count were examined in the children and their families. Furthermore, B-cell function including antibody response to polysaccharide-based pneumococcal vaccination and somatic hypermutation was evaluated. Toll like receptor (TLR) signalling function was evaluated in a functional assay. When children with classical risk factors for IPD were excluded, 15 individuals were eligible. Of whom, sex (40%) children with complement C2 deficiency were identified. Moreover, impaired vaccination response was found in six children: three with concurrent C2 deficiency and three with no other immune abnormality. One patient with a severe TLR signalling dysfunction was diagnosed. In Paper 3, we aimed to assess the impact of PCV7 in Denmark following the first three years of infant immunization. By comparing age-specific disease incidences of IPD in the pre-PCV7 (years 2000-2007) and the PCV7 periods (years 2008-2010) we sought to assess direct and indirect effects on incidence of IPD. In addition, changes in pneumococcal serotype distribution and IPD-related mortality were assessed. We documented a marked decline in the incidence of IPD in both vaccinated and non-vaccinated age groups. The overall incidence of IPD among children aged 0-5 years declined from 26.7 to 16.3 cases per 100,000 (IRR 0.58; 95% confidence interval (CI) [0.48-0.69]). A minor but statistically significant increase in the incidence of IPD due to non-vaccine type IPD was observed in both vaccinated and non-vaccinated groups, but with predominance of serotypes covered by the higher valence pneumococcal conjugate vaccines. This thesis confirms the existing knowledge on underlying diseases predisposing children to IPD, such as cerebrospinal fluid leakage, congenital heart disease and malignant diseases. Our findings support the notion that rIPD in a child should prompt a thorough search for an underlying disease. Moreover, our results underline that rIPD in a child without a known predisposing disease is a major pointer towards primary immune deficiency, such as complement deficiency and B cell dysfunction. This is in line with the guidelines put forward by various specialist committees. Finally, we reported data from the first three years of PCV7 vaccination in the Danish immunization programme, suggesting that the vaccine is effective against all serotypes included in the vaccine when administered in a 2+1 schedule.

The association between antibody levels before and after 7-valent pneumococcal conjugate vaccine immunization and subsequent pneumococcal infection in chronic arthritis patients.

INTRODUCTION: The aim of present study is to inverstigate the association between antibody levels after vaccination with 7-valent pneumococcal conjugate vaccine (PCV7) and subsequent serious pneumococcal infections in rheumatoid arthritis (RA) and spondylarthropathy (SpA) patients. METHODS: A cohort of 497 patients (RA=248 and SpA=249) received a single dose of PCV7. At vaccination, patients were treated with methotrexate (MTX; n=85), anti-tumour necrosis factor (anti-TNF) + MTX (n=169), anti-TNF monotherapy (n=158) and non-steroidal anti-inflammatory drugs (NSAIDs)/analgesics (n=85). Antibody levels of serotypes 6B and 23B were analyzed before and 4 to 6 weeks after vaccination using standard enzyme-linked immunosorbent assay (ELISA). Serious pneumococcal infections (pneumonia/lower respiratory tract infection, meningitis, sepsis, septic arthritis) occurring within 4.5 years after vaccination were identified in the Skåne Healthcare Register using the International Classification of Diseases, tenth revision (ICD-10) codes. The association between post-vaccination antibody levels and protection against infections and determination of protective cutoff levels was explored using receiver operating characteristic (ROC) curves. Predictors of infection were studied using regression analyses. RESULTS: Eighteen infections were registered in 15 patients before vaccination and 27 infections in 23 patients after vaccination. Patients with serious infections after vaccination had significantly lower post-vaccination antibody titres for both 6B (P=0.04) and 23 F (P=0.04). Post-vaccination antibody levels of at least 1.29 mg/L and 1.01 mg/L for 6B and 23, respectively, were associated with better protection from serious infections. Higher age, concomitant prednisolone but not MTX or anti-TNF were associated with such infections. CONCLUSIONS: Patients with more robust antibody responses after vaccination with pneumococcal conjugate vaccine were less likely to suffer from serious infections. High age and prednisolone at vaccination were associated with putative serious pneumococcal infections in this cohort. TRIAL REGISTRATION NUMBER: EudraCT EU 2007-006539-29 and NCT00828997 . Registered 23 January 2009.

Immunogenicity of 13-Valent Pneumococcal Conjugate Vaccine in Pediatric Patients with Inflammatory Bowel Disease.

BACKGROUND: There are only a few studies on immune response to pneumococcal vaccines in patients with inflammatory bowel disease (IBD); all of them assessed polysaccharide vaccines only. The aim of the study was to evaluate the immunogenicity and safety of 13-valent pneumococcal conjugate vaccine (PCV13) in IBD pediatric patients compared with healthy controls. METHODS: This was a multicenter, prospective, and controlled study on children and adolescents aged 5 to 18 years with IBD with no history of pneumococcal immunization. The subjects for the study belonged to one of the following groups: patients with IBD on no immunosuppressive therapy (group A), those on tumor necrosis factor agents or immunomodulators (group B), and healthy controls (group C). The study population received 1 intramuscular injection of PCV13. The primary outcome measure was adequate vaccine response defined as postvaccination titer ≥0.35 µg/mL to all 13 serotypes. Geometric mean titers and geometric mean titer rises were measured for all serotypes. The evidence of local and systemic adverse effects for 5 days after the vaccine was registered. RESULTS: A total of 178 subjects (122 patients and 56 controls) completed the study course. There was no significant difference in the rate of adequate vaccine response between patients with IBD and controls measured 4 to 8 weeks after vaccination (90.4% versus 96.5%, P = 0.5281). Children in group A had higher geometric mean titer rises than children in group B (P = 0.0369). There were no serious adverse events related to PCV13 during the study. CONCLUSIONS: PCV13 is both immunogenic and safe in pediatric patients with IBD.