Effect of HIV-exposure and timing of antiretroviral treatment initiation in children living with HIV on antibody persistence and memory responses to Haemophilus influenzae type b and pneumococcal polysaccharide-protein conjugate vaccines

BackgroundWe investigated the effect of in utero HIV-exposure, timing of antiretroviral treatment (ART) initiation, and ART interruption on memory responses and persistence of immunity induced by pneumococcal (PCV) and Haemophilus influenzae type b (HibCV) polysaccharide-protein conjugate vaccines.MethodsChildren were enrolled (6–12 weeks of age), and vaccinated with a three-dose primary series of 7-valent PCV (PCV7) and HibCV at 6, 10 and 14 weeks of age. Study groups included infants infected with HIV perinatally with CD4+ ≥ 25% initiating ART following immunological or clinical deterioration (ART-Def), or immediately upon enrolment followed by interruption at 40 (ART-Immed/40w) or 96 weeks (ART-Immed/96w); and HIV-uninfected infants with (HEU), and without HIV (HIV-unexpsoed) exposure in utero. Within each group, children were randomized to receive either a booster dose of PCV7 or HibCV at 15 months of age. PCV serotype-specific and polyribosyl ribitol phosphate (PRP) IgG were measured pre-boost, two-weeks post-boost and at two-years of age. Opsonophagocytic activity (OPA) to serotypes 9V, 19F and 23F was measured post-booster dose.ResultsPersistence of IgG to PCV vaccine–serotypes and anti-PRP was similar in all groups of children living with HIV (CLWH) compared to HIV-unexposed children. Anamnestic responses to PCV and HibCV were also similar in all three groups of CLWH compared to HIV-unexposed children. CLWH, however, tended to have lower functional antibody (OPA) titers than HIV-unexposed children after the PCV booster dose for some serotypes. Immunity to PCV and HibCV was similar between the ART-Immed/40w and ART-Immed-96w groups. There were no differences in IgG kinetics between HEU and HIV-unexposed children.ConclusionsA three dose primary series, with or without PCV or HibCV booster doses in CLWH initiated on ART during infancy, would likely be similarly effective in preventing invasive bacterial disease as in HIV-unexposed children.     

Carriage of Haemophilus influenzae is associated with pneumococcal vaccination in Italian children

BackgroundThe pneumococcal population changes observed after the implementation of children immunization with pneumococcal conjugative vaccines (PCV) might have affected the composition of the microbial flora inhabiting the same ecological niche of Streptococcus pneumoniae. The aim of this study was to investigate the effect of PCV immunization, (PCV7 or PCV13), on S. pneumoniae and Haemophilus influenzae colonization in young children in Italy.MethodsNasopharyngeal swabs were obtained from 301 children under 6 years of age (vaccinated or unvaccinated with PCV) during the period January–April 2012. Presence of S. pneumoniae and H. influenzae was investigated using conventional cultural methods. S. pneumoniae isolates were serotyped by the Quellung reaction; capsular type of H. influenzae isolates was determined by PCR. The pattern of associations between the two species and potential risk factors were investigated by a Structural Equation Modelling (SEM) analysis.ResultsThe prevalence of carriage was 31.56% and 43.18% for S. pneumoniae and H. influenzae, respectively. The majority of S. pneumoniae isolates belonged to non vaccine serotypes (non PCV13-types 81.1%) while H. influenzae isolates were all non-typeable. SEM analysis revealed a synergistic association between S. pneumoniae and H. influenzae colonization (rho: 0.27; 95%CI: 0.09–0.46; p = 0.004). In addition, children vaccinated with PCV, either with PCV7 (coef 0.43; 95%CI: 0.07–0.79; p = 0.021) or with PCV13 (coef: 0.45; 95%CI: 0.08–0.82; p = 0.018), were more likely to be colonized by H. influenzae.ConclusionsPneumococcal vaccination increased H. influenzae nasopharyngeal carriage in children. This result highlights that an indirect effect of PCV vaccination can be perturbation of the nasopharyngeal flora. In the era of higher-valent pneumococcal vaccines, surveillance of carriage is crucial to monitor alterations in the bacterial ecosystem, thus preventing possible clinical problems.     

Impact of HIV status and vaccination schedule on bacterial nasopharyngeal carriage following infant immunisation with the pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine in South Africa

BackgroundNasopharyngeal carriage (NPC) of Streptococcus pneumoniae is a precondition for pneumococcal disease and a source of transmission. This trial evaluated NPC of S. pneumoniae and other pathogens post-vaccination with the pneumococcal non-typeable Haemophilus influenzae (NTHi) protein D conjugate vaccine (PHiD-CV) in human immunodeficiency virus (HIV)-infected (HIV+), HIV-exposed-uninfected (HEU), and HIV-unexposed-uninfected (HUU) South African children.MethodsIn this phase III, open, single‐centre, controlled study (ClinicalTrials.gov: NCT00829010), 484 children were stratified by HIV status: 83 HIV+, 101 HEU, and 300 HUU. HIV+ and HEU children received a 3 + 1 PHiD-CV vaccination schedule: primary vaccination, age 6/10/14 weeks, and booster dose, age 9–10 months. HUU infants were randomised (1:1:1) to 3-dose priming and booster (HUU/3+1); 3-dose priming without booster (HUU/3+0); or 2-dose priming and booster (HUU/2+1). Bacterial NPC was assessed 8 times up to 24–27 months of age.ResultsOverall pneumococcal carriage rates were similar across 3+1 groups irrespective of HIV status; trends towards higher carriage rates in the HIV+ than HEU and HUU/3+1 groups were observed at 24–27 months of age. In HUU children, carriage of any pneumococcal serotype was similar for the three different dosing schedules at all timepoints; carriage of vaccine-type pneumococci tended to be lower at 16–19 months and 24–27 months of age in children who had received a booster dose (HUU/2+1 and HUU/3+1 groups) than in the HUU/3+0 group. Carriage rates of NTHi, Staphylococcus aureus and Moraxella catarrhalis were comparable between all groups.ConclusionsHIV infection or exposure did not seem to alter the effect of PHiD-CV on pneumococcal NPC in children during their first 2 years of life. NPC prevalence of vaccine-type pneumococci following vaccination series tended to be lower in children who had received a booster dose in comparison to those who had not.     

Evaluation of the impact of HIV-1 infection and density of common nasopharyngeal bacterial colonizers in South African children immunized with 7-valent pneumococcal conjugate vaccine

BackgroundDue to limitations in standard culture methods, the impact of pneumococcal conjugate vaccine (PCV) immunization on nasopharyngeal bacterial carriage density is unclear, including among HIV-infected children.MethodsThe prevalence and density of serotype/serogroup-specific pneumococcal and other nasopharyngeal colonizing bacteria were investigated in archived swabs of HIV-infected and HIV-uninfected, PCV-7 immunized (at 6, 10 and 14 weeks of age) South African children collected at 9 and 16 months of age. During the course of the study, PCV-immunization of children in Soweto was limited to study-participants, as the vaccine had not been introduced into the public immunization program.ResultsAt 9 months of age, the prevalence of overall pneumococcal colonization was lower in HIV-infected (58.6%) than HIV-uninfected children (69.9%, p = 0.02), mainly due to lower prevalence of non-vaccine-serotype colonization (27.8% vs. 40%, respectively; p = 0.047). The mean-log₁₀ density of pneumococcal colonization was, however, higher in HIV-infected (4.81 CFU/ml) than HIV-uninfected pneumococcal colonized children (4.44 CFU/ml; p = 0.014); mainly due to higher mean-log₁₀ density of PCV7-serotype colonization (4.21 vs. 3.72 CFU/ml; p = 0.014). No difference in the prevalence or density of overall pneumococci was found at 16 months of age. The prevalence of non-vaccine serotype colonization remained 1.7 fold higher in HIV-uninfected (60.4%) than HIV-infected children (50.9%, p = 0.049). Other differences included a lower prevalence of H. influenzae colonization in HIV-infected (42.3% and 56%) than HIV-uninfected children (64.2% and 73.4%) at both 9 and 16 months of age respectively; however, the density of colonization was similar.ConclusionIncreased carriage density of residual PCV7-serotypes might cause HIV-infected children to have a higher risk of pneumococcal disease. The higher carriage density observed in HIV-infected children could be attributed to a combination of factors, including HIV treatment and impaired host immunity. Additional studies are needed.     

Nasopharyngeal carriage of Streptococcus pneumoniae and other bacteria in the 7th year after implementation of the pneumococcal conjugate vaccine in the Netherlands

After introduction of the 7-valent pneumococcal conjugate vaccine (PCV7) in the infant national immunization program (NIP) in the Netherlands in 2006, Streptococcus pneumoniae strains of the non-vaccine serotype 19A emerged and became the dominant serotype in carriage in children and their parents. Similar patterns were observed in other European countries and the United States. Increases in carriage rates of Staphylococcus aureus and non-typeable (NT) Haemophilus influenzae were also observed. After switching of PCV7 to 10-valent vaccine (PCV10) in 2011, a new carriage surveillance study was performed in the winter of 2012/2013. Nasopharyngeal carriage of S. pneumoniae, H. influenzae, S. aureus, and Moraxella catarrhalis was determined by conventional culture in 330 PCV10-vaccinated 11-month-old children, 330 PCV7-vaccinated 24-month-old children, and their parents. Carriage prevalence was compared with similar carriage studies conducted in 2005, 2009, and 2010/2011. Although serotype 19A remained the most frequently carried pneumococcal serotype in children, prevalence of 19A significantly declined in PCV7-vaccinated 24-month-old children (14% to 8%, p = 0.01), but less in PCV10-vaccinated 11-month-old children (12% to 9%, p = 0.31). Carriage of H. influenzae remained stable at an elevated level (65% in 11-month-olds and 69% in 24-month-olds), while the carriage of S. aureus returned to pre-PCV7 levels in 11-month-old children (14% in 2010/2011 to 7% in 2012/2013), but not in 24-month-olds (remained at 7%). Our results might indicate a new balance between replacing non-vaccine pneumococcal serotypes and other potential pathogenic bacteria in nasopharyngeal carriage. Carriage studies are valuable tools in assessing vaccine effects on pathogens circulating in the population, for evaluation of PCV impact, and in predicting changes in respiratory and invasive disease.     

Delayed BCG immunization does not alter antibody responses to EPI vaccines in HIV-exposed and -unexposed South African infants

BackgroundBacille Calmette-Guérin (BCG) is routinely given at birth in tuberculosis-endemic settings due to its protective effect against disseminated tuberculosis in infants. BCG is however contraindicated in HIV-infected infants. We investigated whether delaying BCG vaccination to 14 weeks of age affected vaccine-induced antibody responses to Haemophilus influenzae type b (Hib)-conjugate, pertussis, tetanus and Hepatitis B (HBV) vaccines, in HIV-exposed uninfected (HEU) and -unexposed uninfected (HUU) infants.MethodsInfants were randomized to receive BCG at birth or at 14 weeks of age. Blood was taken at 14, 24, and 52 weeks of age and analyzed for Hib, pertussis, tetanus and HBV specific antibodies.ResultsBCG was given either at birth (106 infants, 51 HEU) or at 14 weeks of age (74 infants, 50 HEU). The timing of BCG vaccination did not influence the antibody response to any antigen studied. However, in a non-randomized comparison, HEU infants had higher Hib antibody concentrations at weeks 14 and 24 (p = 0.001 and <0.001, respectively) and pertussis at week 24 (p = 0.003). Conversely, HEU infants had lower antibody concentrations to HBV at 14 and 52 weeks (p = 0.032 and p = 0.031) with no differences in tetanus titres.ConclusionsHIV exposure, but not the timing of BCG vaccination, was associated with antibody concentrations to Hib, pertussis, HBV and tetanus primary immunization.Clinical Trial Registration: DOH-27-1106-1520.     

Acquisition of Streptococcus pneumoniae in South African children vaccinated with 7-valent pneumococcal conjugate vaccine at 6, 14 and 40 weeks of age

BackgroundSeven-valent pneumococcal conjugate vaccine (PCV7) was introduced into the South African immunization program using 6, 14 and 40 weeks dosing schedule (2 + 1), with no catch-up in older children since April 2009. We investigated pneumococcal colonization acquisition in children who received this schedule and also compared it to historical cohorts of PCV-naïve children (n = 123 in 2007) and children who received a 3 + 1 PCV7 schedule (n = 124 in 2005/06).MethodsTwo hundred and fifty children aged 6–12 weeks were enrolled from December 2009 to April 2010. Participants had nasopharyngeal swabs collected on eight occasions between enrolment and 2-years of age. Standard methods were undertaken for bacterial culture and Streptococcus pneumoniae were serotyped using the Quellung method. Pneumococcal and Staphylococcus aureus colonization in the present study was compared to colonization in two historical longitudinal cohorts.ResultsS. pneumoniae was identified in 1081 (61.4%) of 1761 swabs collected in the current cohort. Pneumococcal colonization peaked at 41-weeks of age (76.8%) and decreased to 62.8% by 2-years of age (p = 0.002); PCV7-serotype colonization decreased during the same period from 28.6% to 15.6% (p = 0.001). Children from the current cohort compared to PCV-naïve children were less likely to be colonized by PCV7-serotypes from 40-weeks to 2-years of age and acquired PCV7-serotypes less frequently. No differences in overall pneumococcal, PCV7-serotype and non-PCV7-serotype colonization or new serotype acquisitions were detected comparing the current cohort to the historical cohort who received the 3 + 1 PCV7 schedule. Staphylococcus aureus colonization was similar in all three cohorts.ConclusionA 2 + 1 PCV7 schedule implemented in South Africa was temporally associated with reduced risk of vaccine-serotype colonization compared to historically unvaccinated children. Also, vaccine-serotype acquisition rate using the 2 + 1 schedule was similar to that in the 3 + 1 dosing cohort, suggesting that similar indirect protection against pneumococcal disease could be derived from either schedule in South Africa.     

Changes in pathogens and pneumococcal serotypes causing community-acquired pneumonia in The Netherlands

BackgroundIn 2006 a 7-valent pneumococcal conjugate vaccine (PCV7) was introduced in the immunisation programme for infants in The Netherlands and replaced by PCV10 in 2011. Limited data exist about the impact of PCV on the aetiology of CAP as a whole. The aim of the present study is to describe the overall changes in microbial aetiology, pneumococcal burden (including non-bacteraemic pneumococcal pneumonia) and its serotypes in adult community-acquired pneumonia (CAP) after the introduction of these PCVs.MethodsHospitalised adult CAP patients who participated in three consecutive trials were studied (2004–2006 (n = 201), 2007–2009 (n = 304) and 2012–2016 (n = 300) and considered as pre-PCV7, PCV7 and PCV10 period). Extensive conventional microbiological testing was applied for all patients. In addition, patients with a serotype-specific pneumococcal antibody response were diagnosed with pneumococcal CAP. Changes in proportions of causative pathogens and distributions of pneumococcal serotypes were calculated.ResultsThe proportion of pneumococcal CAP decreased from 37% (n = 74/201) to 26% (n = 77/300) comparing the pre-PCV7 period with the PCV10 period (p = 0.01). For other pathogens, including Legionella spp., Mycoplasma pneumoniae, S. aureus, H. influenzae, and respiratory viruses, no sustained shifts were observed in their relative contribution to the aetiology of CAP. Within the pneumococcal CAP patients, we observed a decrease in PCV7 and an increase in non-PCV10 serotype disease. PCV10-extra type disease did not decrease significantly comparing the PCV10 period with the pre-PCV7 and PCV7 period, respectively. Notably, PCV7 type disease decreased both in bacteraemic and non-bacteraemic patients.ConclusionsOur findings confirm that PCV introduction in infants impact the microbial aetiology of adult CAP and suggest herd effects in adults with CAP after introduction of PCVs in children.     

Immunogenicity of 13-valent pneumococcal conjugate vaccine among children with underlying medical conditions

BackgroundStreptococcus pneumoniae is a leading cause of vaccine-preventable disease in children under 5 years. Immunocompromised children and those with underlying diseases are at increased risk of severe complications from vaccine-preventable infections. We studied the humoral immune response to the 13-valent pneumococcal conjugate vaccine (PCV13) in children with HIV-infection, kidney or lung disease and compared this to the response in healthy control children.MethodsChildren aged 12–71 months with underlying conditions including HIV-infection and those with kidney and lung diseases (at-risk children), and a healthy control group were vaccinated with PCV13. The at-risk children received two doses of PCV13 and the controls received one dose. Serotype-specific antibodies for all PCV13 serotypes were measured by a luminex-based enzyme immunoassay at baseline and post-vaccination.ResultsAfter the first PCV13 dose, the fold-increase in serotype-specific antibody geometric mean concentrations (GMCs) from baseline and the percentage of participants with ≥4-fold-increase in antibody concentrations was similar between the control and at-risk children. GMCs were, however, lower for three of the 13 serotypes in HIV-infected children, higher for serotype 6B in children with kidney disease and higher for serotypes 6B and 14 in children with lung disease. After second vaccine dose HIV-infected children had an increase in GMCs from post-first dose for nine serotypes but the percentage of participants with ≥4-fold-increase from baseline was similar post-second dose compared to post-first dose except for serotypes 6A and 19F. In children with kidney or lung diseases the immune responses after second vaccine dose were similar to post-first dose. Attenuated responses were observed for serotypes 3 and 19A in all study-groups, which was especially pronounced in the at-risk groups.ConclusionAll study-groups mounted an immune response to PCV13, with the at-risk groups having responses that were mostly similar to the control children.     

Long-term impact of pneumococcal polysaccharide vaccination on nasopharyngeal carriage in children previously vaccinated with various pneumococcal conjugate vaccine regimes

Previously, the Fiji Pneumococcal Project (FiPP) evaluated reduced dose immunization schedules that incorporated pneumococcal protein conjugate and/or polysaccharide vaccine (PCV7 and 23vPPV, respectively). Immune hyporesponsiveness was observed in children vaccinated with 23vPPV at 12 months of age compared with children who did not receive 23vPPV.Here we assess the long-term impact of 23vPPV vaccination on nasopharyngeal carriage rates and densities of Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus and Moraxella catarrhalis. Nasopharyngeal swabs (n = 194) were obtained from healthy children who participated in FiPP (now aged 5–7 years). S. pneumoniae were isolated and identified by standard culture-based methods, and serotyped using latex agglutination and the Quellung reaction. Carriage rates and densities of S. pneumoniae, H. influenzae, S. aureus and M. catarrhalis were determined using real-time quantitative PCR.There were no differences in the rate or density of S. pneumoniae, H. influenzae or M. catarrhalis carriage by PCV7 dose or 23vPPV vaccination in the vaccinated participants overall. However, differences were observed between the two main ethnic groups: Fijian children of Indian descent (Indo-Fijian) were less likely to carry S. pneumoniae, H. influenzae and M. catarrhalis, and there was evidence of a higher carriage rate of S. aureus compared with indigenous Fijian (iTaukei) children. Polysaccharide vaccination appeared to have effects that varied between ethnic groups, with 23vPPV vaccination associated with a higher carriage rate of S. aureus in iTaukei children, while there was a lower carriage rate of S. pneumoniae associated with 23vPPV vaccination in Indo-Fijian children.Overall, polysaccharide vaccination had no long-term impact on pneumococcal carriage, but may have impacted on S. aureus carriage and have varying effects in ethnic groups, suggesting current WHO vaccine schedule recommendations against the use of 23vPPV in children under two years of age are appropriate.     

Use of administrative records to assess pneumococcal conjugate vaccine impact on pediatric meningitis and pneumonia hospitalizations in Rwanda

BackgroundOngoing surveillance is critical to assessing pneumococcal conjugate vaccine (PCV) impact over time. However, robust prospective studies are difficult to implement in resource-poor settings. We evaluated retrospective use of routinely collected data to estimate PCV impact in Rwanda.MethodsWe collected data from admission registers at five district hospitals on children age <5 years admitted for suspected meningitis and pneumonia during 2002–2012. We obtained clinical and laboratory data on meningitis from sentinel surveillance at the national reference hospital in Kigali. We developed multivariable logistic regression models to estimate PCV effectiveness (VE) against severe pneumonia and probable bacterial meningitis and Poisson models to estimate absolute rate reductions. Haemophilus influenzae type b vaccine was introduced in January 2002, PCV7 in April 2009 and PCV13 in August 2011.ResultsAt the district hospitals, the severe pneumonia and suspected meningitis hospitalization rates decreased by 70/100,000 and 11/100,000 children for 2012 compared to baseline, respectively. VE against severe pneumonia calculated from logistic regression was 54% (95% CI 42–63%).In Kigali, from 2002 to 2012, annual suspected meningitis cases decreased from 170 pre-PCV7 to 40 post-PCV13 and confirmed pneumococcal meningitis cases from 7 to 0. VE against probable bacterial meningitis was 42% (95% CI −4% to 68%).ConclusionIn a resource-poor African setting, analysis of district hospital admission logbooks and routine sentinel surveillance data produced results consistent with more sophisticated impact studies conducted elsewhere. Our findings support applying this methodology in other settings and confirm the benefits of PCV in Rwanda.     

Immunogenicity and safety of 7-valent pneumococcal conjugate vaccine (PCV7) in children aged 2–5 years in China

BackgroundThe widespread use of pneumococcal conjugate vaccines (PCVs) has significantly decreased pneumococcal disease worldwide. However, China has not adopted PCVs in their national immunization schedules and had only approved these vaccines for children aged 2–15 months by 2020.MethodsIn an open-label trial, enrolled healthy children aged 2–5 years old were randomized 1:1 and divided into a 7-valent pneumococcal conjugate vaccine (PCV7) group and a Haemophilus influenzae type b conjugate vaccine (Hib) group. Children in the PCV7 group received a single dose of PCV7, and the Hib group received a single dose of Hib vaccine. Blood samples were collected before and 6 months after vaccination. Immunogenicity and safety of PCV7 were assessed at prespecified time points.ResultsSix months after a single dose of PCV7, children in the PCV7 group for all 7 serotypes, IgG mean concentrations (GMCs) and opsonophagocytic geometric mean titres (GMTs) were significantly higher (P < .001) than at baseline, and the proportion of IgG ≥ 0.35 µg/mL ranged from 90.0% to 100%. Although the antibody level increased with age, preexisting antibodies did not induce hyporesponsiveness to PCV7. In the Hib group, the antibody levels were not significantly different or had changed slightly at 6 months. PCV7 was well tolerated in all age groups, and no serious adverse events (AEs) emerged during this study.ConclusionsA single dose of PCV7 was immunogenic and safe for Chinese children aged 2–5 years, and the preexisting antibodies against the PCV7 serotypes did not change the response to vaccination. The findings supported the effectiveness of PCV7 in this age group. PCVs with broader serotype coverage are expected to expand pneumococcal disease protection.     

Impact of PCV7/PCV13 introduction on invasive pneumococcal disease (IPD) in young children: Comparison between meningitis and non-meningitis IPD

BackgroundThe worldwide introduction of pneumococcal conjugate vaccines (PCV) into National Immunization Programs resulted in rapid and substantial reduction of invasive pneumococcal disease (IPD) rates in children. However, the reduction of meningitis vs. non-meningitis IPD (nm-IPD) was not yet fully elucidated. We compared 7-valent and 13-valent PCV (PCV7 and PCV13) impact on pneumococcal-meningitis vs. nm-IPD in Israeli children <5 years.MethodsWe conducted an ongoing nationwide, prospective, population-based, active surveillance. PCV7 and PCV13 were implemented in Israel in July 2009 and November 2010, respectively. All pneumococcal isolates (blood and/or CSF) from IPD episodes in children <5 years from July 2000 through June 2015 were included. Extrapolation for missing serotypes (34.7% of all isolates) was conducted.Results4163 IPD cases were identified; 3739 nm-IPD (89.8%) and 424 meningitis (10.2%). During the pre-PCV period (2000–2008), children <12 months constituted 52.1% and 33.7% of meningitis and nm-IPD, respectively (p < 0.001). The respective proportions of non-PCV13 serotypes (non-VT) were 18.2% vs. 10.1%, (p < 0.001).Comparing the last study year (2014–2015) to the mean of pre-PCV period, meningitis incidence in children <5 years decreased non-significantly by 27%, while nm-IPD decreased significantly by 69%. Dynamic rates of meningitis and nm-IPD caused by PCV13 serotypes were similar, with 93% and 95% overall reductions, respectively. However, non-VT increased in meningitis relatively to nm-IPD, mainly in children <24 months. Serotype 12F rose sharply and significantly since 2009–2010 through 2014–2015 (28.6% of all non-VT meningitis in children <24 m).ConclusionsThe overall impact of PCV7/PCV13 in children <5 years in Israel was less prominent in meningitis than in nm-IPD. This could be attributed to the younger age of children with meningitis and differences in causative serotypes between the two groups, as the decline of the incidence of meningitis and nm-IPD caused by vaccine-serotypes is similar. Continuous monitoring of meningitis and nm-IPD is warranted.     

Changes in empyema among U.S. children in the pneumococcal conjugate vaccine era

BackgroundParapneumonic empyema, a serious complication of pneumonia, started increasing among U.S. children before the introduction of the 7-valent pneumococcal conjugate vaccine (PCV7) in 2000, and continued afterwards. This increase was due in part to pneumococcal serotypes not included in PCV7 that were included in the new 13-valent (PCV13) vaccine introduced in 2010. We assessed changes in the incidence of empyema hospitalizations among U.S. children after PCV13 introduction.MethodsWe calculated annualized empyema hospitalization rates among U.S. children <18 years using Nationwide Inpatient Sample and Census data (1997–2013) for four periods based on PCV7 and PCV13 introductions. Relative rates (RR) and 95% confidence intervals (CI) were calculated by age group and sex, comparing PCV7 [early-PCV7 (2001–2005) and late-PCV7 (2006–2009)] and PCV13 (2011–2013) periods with the pre-PCV7 period (1997–1999). Secondary analyses examined changes in pneumococcal, streptococcal, staphylococcal and unspecified empyema.ResultsAmong children <18 years of age, annualized empyema hospitalization rates peaked at 3.6 per 100,000 in the late-PCV7 period compared with 2.1 per 100,000 in the pre-PCV7 period [RR: 1.70 (95% CI: 1.11–2.60)]. However, annualized rates in the post-PCV13 period declined to 2.0 per 100,000, similar to rates in the pre-PCV7 period. Empyema rates among children <2 years were lower in the post-PCV13 period compared to the pre-PCV7 period [RR: 0.77 (95% CI: 0.61–0.96)], but rates in the two periods among children 2–4 and 5–17 years were similar. Most empyema were of unspecified etiology. Pneumococcal and unspecified empyema declined after PCV13 introduction.ConclusionsAlthough empyema hospitalization rates among U.S. children peaked after PCV7 introduction, rates decreased substantially following the introduction of PCV13.     

Improving immunity to Haemophilus influenzae in children with chronic suppurative lung disease

BackgroundEndobronchial infections related to non-typeable Haemophilus influenzae (NTHi) are common in children and adults with suppurative airway disease such as bronchiectasis and COPD. Impaired cell mediated immune responses to NTHi have been described in these patients. Currently there are no interventions known to correct the deficiency in cell mediated immune responses to NTHi. The aim of this study was to determine if receipt of a conjugate vaccine containing protein D from H. influenzae is associated with improvement in NTHi-specific cytokine responses in children with chronic suppurative lung disease.MethodsBlood mononuclear cells from 107 young children with chronic suppurative lung disease and 32 healthy control children were stimulated in vitro with NTHi. We compared the cytokine production of stimulated mononuclear cells from children who had received the pneumococcal H. influenzae protein D conjugate vaccine with cells from children who received pneumococcal vaccines without protein D. Protein D-specific IgG1 was quantified in plasma.ResultsChildren with chronic suppurative lung disease who received ≥3 doses of the protein D conjugate vaccine produced significantly more IFNγ than children who received the alternative vaccines without protein D (median 939 versus 338 pg/ml; p = 0.007). Importantly, the amount of IFNγ produced by those vaccinated with the conjugate vaccine approached the levels observed in cells from healthy children. The conjugate vaccine was also associated with small but significant increases in IL-13 (p < 0.001) and IL-5 (p = 0.007). Protein D-specific IgG1 levels correlated with the number of PHiD-CV doses (p = 0.02).ConclusionVaccination with PHiD-CV is associated with improvements in NTHi-specific cell-mediated and humoral immune responses in children with chronic suppurative lung disease.     

Evaluation of the association of pneumococcal conjugate vaccine immunization and density of nasopharyngeal bacterial colonization using a multiplex quantitative polymerase chain reaction assay

BackgroundNasopharyngeal bacterial colonization is a pre-requisite for developing bacterial mucosal and invasive disease. Pneumococcal conjugate vaccine (PCV) immunization of children reduces their risk of colonization by vaccine-serotypes, which could affect the biome of the nasopharynx in relation to colonization by other bacteria. This study evaluated the association of PCV immunization on the prevalence density of nasopharyngeal colonization by common, potentially pathogenic bacteria.MethodsA multiplex qPCR assay was used to evaluate bacterial nasopharyngeal colonization by 7-valent PCV (PCV7) serotypes, non-vaccine serotypes (NVT), Haemophilus influenzae, Staphylococcus aureus, Moraxella catarrhalis, and Neisseria meningitidis in PCV7-vaccinated and PCV-unvaccinated African children at two time points.ResultsPCV7 vaccination was associated with a higher prevalence of NVT and H. influenzae at 9 and 16 months, respectively. While the prevalence of S. aureus was higher in PCV7-vaccinated children at 9 months, no difference was found at 16 months. The density of PCV7 serotypes (3.8 vs. 3.4 log₁₀; p = 0.048), NVT (3.6 vs. 3.1 log₁₀; p = 0.018), H. influenzae (4.34 vs. 3.86 log₁₀; p = 0.008), M. catarrhalis (3.52 vs. 2.98 log₁₀; p < 0.001) and S. aureus (4.02 vs. 3.06 log₁₀; p = 0.02) was higher among PCV-vaccinated compared to PCV-unvaccinated children at 9 months, although, this difference diminished at 16 months of age.ConclusionThe reduction in PCV7-serotype colonization impacted on colonization prevalence and density of other bacterial species of the nasopharynx. The clinical relevance of this needs further exploration in relation to mucosal and invasive disease outcomes, as well as for higher valency PCV vaccines.     

Effect on nasopharyngeal pneumococcal carriage of replacing PCV7 with PCV13 in the Expanded Programme of Immunization in The Gambia

IntroductionIn 2011, two years after the introduction of 7-valent Pneumococcal conjugate vaccine (PCV7), the Gambian immunization programme replaced PVC7 with PCV13 (13-valent). Our objective was to assess the additional impact of PCV13 on prevalence of pneumococcal nasopharyngeal carriage.MethodsWe recruited healthy Gambian infants who had received three PCV doses. Nasopharyngeal swabs were collected from infants and their mothers during two cross-sectional surveys (CSS) conducted in infants vaccinated with PCV7 (CSS1) and vaccinated with PCV13 (CSS2). Pneumococci were isolated and serotyped following standardized methods. Whole genome sequencing was performed on non-typable pneumococcus isolated in CSS1 and CSS2.Results339 and 350 infants and their mothers were recruited in CSS1 and CSS2, respectively. Overall prevalence of pneumococcal carriage was 85.4% in infants. Among infants, prevalence of vaccine type (VT) carriage was lower in CSS2 [9.4% versus 4.9% (p = 0.025) for PCV7-VT; 33.3% versus 18.3% (p < 0.001) for PCV13-VT and 23.9% versus 13.7% (p = 0.001) for the 6 additional serotypes included in PCV13]. At CSS2, there was a decrease of serotypes 6A (from 15.3% to 5.7%, p < 0.001) and 19F (from 5.6% to 1.7%, p = 0.007), and an increase of non-typable pneumococci (0.3–6.0%, p < 0.001), most of which (82.4%) were from typable serotype backgrounds that had lost the ability to express a capsule. Prevalence of overall and VT carriage in mothers was similar in CSS1 and CSS2.ConclusionsReplacing PCV7 for PCV13 rapidly decreased prevalence of VT carriage among vaccinated Gambian infants. An indirect effect in mothers was not observed yet. Vaccine-driven selection pressure may have been responsible for the increase of non-typable isolates.     

Vitamin D levels and influenza vaccine immunogenicity among HIV-infected and HIV-uninfected adults

BackgroundVaccination is the most important preventive strategy against influenza, however post-vaccination antibody responses are often inadequate especially among HIV-infected persons. Vitamin D deficiency has been suggested to adversely influence immune responses and is highly prevalent among HIV-infected adults. Therefore, we evaluated the association between 25-hydroxyvitamin D [25(OH)D] levels and post-influenza vaccination responses.MethodsWe conducted a prospective cohort study evaluating the immunogenicity of monovalent influenza A (H1N1) vaccination among both HIV-infected and HIV-uninfected adults (18–50 years of age) during the 2009–2010 influenza season. Antibody titers were evaluated at baseline, day 28, and 6 months post-vaccination using hemagluttination inhibition assays. Serum 25(OH)D levels were measured at day 28. Univariate and multivariate regression analyses examined the association between 25(OH)D levels [categorized as <20 ng/ml (deficiency) vs. ⩾20 ng/ml] with the primary outcome of seroconversion. Secondary outcomes included seroprotection; a ⩾4-fold increase in titers; and geometric mean titers post-vaccination. Analyses were repeated using 25(OH)D levels as a continuous variable.ResultsA total of 128 adults [64 HIV-infected (median CD4 count 580 cells/mm³) and 64 HIV-uninfected] were included. Seroconversion at day 28 post-vaccination was achieved in fewer HIV-infected participants compared with HIV-uninfected participants (56% vs. 74%, p = 0.03). Vitamin D deficiency was more prevalent among HIV-infected persons vs. HIV-uninfected persons (25% vs. 17%), although not significantly different (p = 0.39). There were no associations found between lower 25(OH)D levels and poorer antibody responses at day 28 or 6 months for any of the study outcomes among either HIV-infected or HIV-uninfected adults.ConclusionVitamin D deficiency was common among both HIV-infected and HIV-uninfected adults, but lower levels did not predict antibody responses after H1N1 (2009) influenza vaccination. Low 25(OH)D levels do not explain poorer post-vaccination responses among HIV-infected persons.     

A 13-year survey of pneumococcal nasopharyngeal carriage in children with acute otitis media following PCV7 and PCV13 implementation

BackgroundThis nasopharyngeal (NP) carriage surveillance study was requested by the European Agency for the Evaluation of Medicinal Products as a post-licensing commitment to determine whether the use of the pneumococcal conjugate vaccines (PCVs) including 7 then 13 valents (introduced in 2001 and 2010, respectively) caused a shift in the distribution of Streptococcus pneumoniae serotypes in children with acute otitis media and modified the resistance of this bacterial species to antibiotics.MethodsBetween 2001 and 2014, 121 pediatricians obtained nasopharyngeal swabs from children with acute otitis media aged 6–24 months. The swabs were analyzed by the French National Reference Centre for Pneumococci. Demographics, medical history and physical examination findings were recorded.ResultsOver the 13 years, among the 7991 enrolled patients, the proportion of PCV-vaccinated children (≥1 dose) increased (54.3–99.7%, p < 0.001). Overall, pneumococcal carriage was reduced from 71.2% to 56.2% from 2001 to 2014 (p < 0.001) and carriage of PCV7 serotypes (STs) from 44.5% to 1.2% (p < 0.001). The carriage of 6 additional STs plus 6C increased from 17.2% to 24.3% from 2001 to 2010 (p < 0.001) and decreased after PCV13 implementation (21.4–3.5%, p < 0.001). The proportion of ST 19A carriage increased from 8.6% to 15.8% from 2001 to 2010 (p < 0.001) and decreased to 1.2% in 2014. After PCV13 implementation, the most frequently carried non-PCV13 STs were ST 15B/C, 11A, 15A, and 35B. Penicillin non-susceptible pneumococcal strains decreased from 67.1% in 2001 to 33.1% in 2014 (p < 0.001).ConclusionsBy the number of patients enrolled and the duration, this study is the largest performed to date. It allows to demonstrate a strong impact of PCVs and to describe the complex dynamics of pneumococcal carriage during AOM. As pneumococcal carriage decreased during AOM, a reduction in the incidence of pneumococcal AOM could be expected.