The evidence for using conjugate vaccines to protect HIV-infected children against pneumococcal disease

Severe Recurrent Bacterial Pneumonia Among Children Living With HIV

BACKGROUND

Bacterial pneumonia imparts a major morbidity and mortality burden on children living with HIV, yet effective prevention and treatment options are underutilized. We explored clinical factors associated with severe recurrent bacterial pneumonia among children living with HIV.

METHODS

Children enrolled in the TREAT Asia Pediatric HIV Observational Database were included if they started antiretroviral therapy (ART) on or after January 1st, 2008. Factors associated with severe recurrent bacterial pneumonia were assessed using competing-risk regression.

RESULTS

A total of 3,944 children were included in the analysis; 136 cases of severe recurrent bacterial pneumonia were reported at a rate of 6.5 [95% confidence interval (CI): 5.5-7.7] events per 1,000 patient-years. Clinical factors associated with severe recurrent bacterial pneumonia were younger age [adjusted subdistribution hazard ratio (aHR): 4.4 for <5 years versus ≥10 years, 95% CI: 2.2-8.4, P < 0.001], lower weight-for-age z-score (aHR: 1.5 for <-3.0 versus >-2.0, 95% CI: 1.1-2.3, P = 0.024), pre-ART diagnosis of severe recurrent bacterial pneumonia (aHR: 4.0 versus no pre-ART diagnosis, 95% CI: 2.7-5.8, P < 0.001), past diagnosis of symptomatic lymphoid interstitial pneumonitis or chronic HIV-associated lung disease, including bronchiectasis (aHR: 4.8 versus no past diagnosis, 95% CI: 2.8-8.4, P < 0.001), low CD4% (aHR: 3.5 for <10% versus ≥25%, 95% CI: 1.9-6.4, P < 0.001) and detectable HIV viral load (aHR: 2.6 versus undetectable, 95% CI: 1.2-5.9, P = 0.018).

CONCLUSIONS

Children <10-years-old and those with low weight-for-age, a history of respiratory illness, low CD4% or poorly controlled HIV are likely to gain the greatest benefit from targeted prevention and treatment programs to reduce the burden of bacterial pneumonia in children living with HIV.

Evolution of pneumococcal serotype epidemiology in Botswana following introduction of 13-valent pneumococcal conjugate vaccine

Pneumococcal conjugate vaccines reduce the burden of invasive pneumococcal disease, but the sustained effect of these vaccines can be diminished by an increase in disease caused by non-vaccine serotypes. To describe pneumococcal serotype epidemiology in Botswana following introduction of 13-valent pneumococcal conjugate vaccine (PCV-13) in July 2012, we performed molecular serotyping of 268 pneumococcal strains isolated from 221 children between 2012 and 2017. The median (interquartile range) age of the children included in this analysis was 6 (3,12) months. Fifty-nine percent of the children had received at least one dose of PCV-13 and 35% were fully vaccinated with PCV-13. While colonization by vaccine serotypes steadily declined following PCV-13 introduction, 25% of strains isolated more than 3 years after vaccine introduction were PCV-13 serotypes. We also observed an increase in colonization by non-vaccine serotypes 21 and 23B, which have been associated with invasive pneumococcal disease and antibiotic resistance in other settings.

The Etiology of Pneumonia in HIV-infected Zambian Children: Findings From the Pneumonia Etiology Research for Child Health (PERCH) Study

BACKGROUND

Despite recent declines in new pediatric HIV infections and childhood HIV-related deaths, pneumonia remains the leading cause of death in HIV-infected children under 5. We describe the patient population, etiology and outcomes of childhood pneumonia in Zambian HIV-infected children.

METHODS

As one of the 9 sites for the Pneumonia Etiology Research for Child Health study, we enrolled children 1-59 months of age presenting to University Teaching Hospital in Lusaka, Zambia, with World Health Organization-defined severe and very severe pneumonia. Controls frequency-matched on age group and HIV infection status were enrolled from the Lusaka Pediatric HIV Clinics as well as from the surrounding communities. Clinical assessments, chest radiographs (CXR; cases) and microbiologic samples (nasopharyngeal/oropharyngeal swabs, blood, urine, induced sputum) were obtained under highly standardized procedures. Etiology was estimated using Bayesian methods and accounted for imperfect sensitivity and specificity of measurements.

RESULTS

Of the 617 cases and 686 controls enrolled in Zambia over a 24-month period, 103 cases (16.7%) and 85 controls (12.4%) were HIV infected and included in this analysis. Among the HIV-infected cases, 75% were <1 year of age, 35% received prophylactic trimethoprim-sulfamethoxazole, 13.6% received antiretroviral therapy and 36.9% of caregivers reported knowing their children's HIV status at time of enrollment. A total of 35% of cases had very severe pneumonia and 56.3% had infiltrates on CXR. Bacterial pathogens [50.6%, credible interval (CrI): 32.8-67.2], Pneumocystis jirovecii (24.9%, CrI: 15.5-36.2) and Mycobacterium tuberculosis (4.5%, CrI: 1.7-12.1) accounted for over 75% of the etiologic fraction among CXR-positive cases. Streptococcus pneumoniae (19.8%, CrI: 8.6-36.2) was the most common bacterial pathogen, followed by Staphylococcus aureus (12.7%, CrI: 0.0-25.9). Outcomes were poor, with 41 cases (39.8%) dying in hospital.

CONCLUSIONS

HIV-infected children in Zambia with severe and very severe pneumonia have poor outcomes, with continued limited access to care, and the predominant etiologies are bacterial pathogens, P. jirovecii and M. tuberculosis.

Association of nasopharyngeal viruses and pathogenic bacteria in children and their parents with and without HIV

BACKGROUND

Bacteria and respiratory viruses co-occur in the nasopharynx, and their interactions may impact pathogenesis of invasive disease. Associations of viruses and bacteria in the nasopharynx may be affected by HIV.

METHODS

We conducted a nested case-control study from a larger cohort study of banked nasopharyngeal swabs from families with and without HIV in West Bengal India, to look at the association of viruses and bacteria in the nasopharynx of parents and children when they are asymptomatic. Quantitative polymerase chain reaction for 4 bacteria and 21 respiratory viruses was run on 92 random nasopharyngeal swabs from children--49 from children living with HIV (CLH) and 43 from HIV uninfected children (HUC)-- and 77 swabs from their parents (44 parents of CLH and 33 parents of HUC).

RESULTS

Bacteria was found in 67% of children, viruses in 45%, and both in 27% of child samples. Staphylococcus aureus (53%) was the most common bacteria, followed by Streptococcus pneumoniae (pneumococcus) (37%) in children and parents (53, 20%). Regardless of HIV status, viruses were detected in higher numbers (44%) in children than their parents (30%) (p = 0.049), particularly rhinovirus (p = 0.02). Human rhinovirus was the most frequently found virus in both CLH and HUC. Children with adenovirus were at six times increased risk of also having pneumococcus (Odds ratio OR 6, 95% CI 1.12-31.9) regardless of HIV status. In addition, the presence of rhinovirus in children was associated with increased pneumococcal density (Regression coeff 4.5, 1.14-7.9). In CLH the presence of rhinovirus increased the risk of pneumococcal colonization by nearly sixteen times (OR 15.6, 1.66-146.4), and, pneumococcus and S. aureus dual colonization by nearly nine times (OR 8.7).

CONCLUSIONS

Children more frequently carried viruses regardless of HIV status. In CLH the presence of rhinovirus, the most frequently detected virus, significantly increased co-colonization with pneumococcus and S. aureus.

Serotypes and antibiotic susceptibility profile of Streptococcus pneumoniae isolated from nasopharynges of children infected with HIV in Jakarta, Indonesia, pre- and post-pneumococcal vaccination

The aim of this prospective study was to investigate the serotypes and antibiotic susceptibility of S. pneumoniae carried by children infected with HIV before and after vaccination with the seven-valent pneumococcal conjugate vaccine in Jakarta, Indonesia in 2013. We collected nasopharyngeal swab specimens from 52 children pre-vaccination and 6 months post-vaccination. Serotyping was performed by conventional multiplex polymerase chain reaction and Quellung reaction. The antibiotic susceptibility profile was obtained by disc diffusion. We determined that 27 (52%) and 24 (46%) of the 52 children carried S. pneumoniae during pre- and post-vaccination periods, respectively with the majority of the isolates being non-vaccine type strains (85% pre-vaccination and 75% post-vaccination). Serotypes 34, 6C, and 16F (two strains each) were the most commonly identified serotypes at pre-vaccination. Serotypes 23A (three strains) and 19F (two strains) were the most commonly identified serotypes post-vaccination. In general, isolates were most commonly susceptible to chloramphenicol (88%) and clindamycin (88%), followed by erythromycin (84%), trimethoprim-sulphamethoxazole (69%), tetracycline (61%), and penicillin (59%). In conclusion, serotypes of S. pneumoniae isolated from the nasopharynges of children infected with HIV varied and were more likely to be non-vaccine type strains both before and after vaccination.

Respiratory Complications in Children and Adolescents with Human Immunodeficiency Virus

Respiratory complications comprise a large proportion of the burden of mortality and morbidity in children with human immunodeficiency virus (HIV). HIV-associated lower respiratory tract infection (LRTI) has declined in incidence with early diagnosis and use of antiretroviral therapy (ART) but is widespread in areas with limited access to ART. HIV-exposed uninfected infants have a higher risk of LRTI early in life than unexposed infants. Pulmonary tuberculosis (PTB) presenting as acute or chronic disease is common in highly TB endemic areas. Chronic lung disease is common; preceding LRTI, PTB or late initiation of ART are risk factors.

Divergent serotype replacement trends and increasing diversity in pneumococcal disease in high income settings reduce the benefit of expanding vaccine valency

Streptococcus pneumoniae is a significant cause of otitis media, pneumonia, and meningitis. Only seven of the approximately 100 serotypes were initially included in the pneumococcal polysaccharide conjugate vaccine (PCV) in 2000 before it was expanded in subsequent years. Although the invasive pneumococcal disease (IPD) incidence due to vaccine serotypes (VT) has declined, partial replacement by non-vaccine serotypes (NVT) was observed following widespread vaccine uptake. We conducted a trend analysis assembling the available evidence for PCV impact on European, North American and Australian national IPD. Significant effectiveness against VT IPD in infants was observed, although the impact on national IPD incidence varied internationally due to serotype replacement. Currently, NVT serotypes 8, 9N, 15A and 23B are increasing in the countries assessed, although a variety of other NVTs are affecting each country and age group. Despite these common emerging serotypes, there has not been a dominant IPD serotype post-vaccination as there was pre-vaccination (serotype 14) or post-PCV7 (serotype 19A), suggesting that future vaccines with additional serotypes will be less effective at targeting and reducing IPD in global populations than previous PCVs. The rise of diverse NVTs in all settings’ top-ranked IPD-causing serotypes emphasizes the urgent need for surveillance data on serotype distribution and serotype-specific invasiveness post-vaccination to facilitate decision making concerning both expanding current vaccination programmes and increasing vaccine valency.

Impact of pneumococcal conjugate vaccine on the carriage density of Streptococcus pneumoniae and Staphylococcus aureus in children living with HIV: a nested case-control study

Nasopharyngeal colonization density of Streptococcus pneumoniae (pneumococcus) is associated with disease severity and transmission. Little is known about the density of pneumococcal carriage in children with HIV (CLH). Pneumococcal vaccines may impact the density of pneumococcus and competing microbes within the nasopharynx. We examined the impact of one dose of PCV13 on carriage density of pneumococcus and Staphylococcus aureus, in CLH, HIV-uninfected children (HUC), and their unvaccinated parents. We conducted a pilot-nested case-control study, within a larger prospective cohort study, on the impact of PCV13, in families in West Bengal India. Quantitative real-time PCR was run on 147 nasopharyngeal swabs from 27 CLH and 23 HUC, and their parents, before and after PCV13 immunization. CLH had higher median pneumococcal carriage density, compared to HUC: 6.28 × 108 copies/mL vs. 2.11 × 105 copies/mL (p = .005). Following one dose of PCV13, pneumococcal densities dropped in both groups, with an increase in S. aureus carriage to 80% from 48% in CLH, and to 60% in HUC from 25%. While limited in sample size, this pilot study shows that CLH carried higher densities of pneumococcus. PCV13 was associated with a decrease in pneumococcal density and a temporal increase in S. aureus carriage regardless of HIV status.

Immunogenicity and safety of the 13-valent pneumococcal conjugate vaccine in patients with immunocompromising conditions: a review of available evidence

Immunocompromising conditions increase the risk of invasive pneumococcal disease (IPD). Vaccine uptake in patients with these conditions may be low in part because of concerns about decreased immunogenicity and safety in these high-risk groups. We conducted a literature search to identify publications describing antibody responses to 13-valent pneumococcal conjugate vaccine (PCV13) in immunocompromised individuals recommended for PCV13 vaccination by the US Advisory Committee on Immunization Practices (ACIP). This review summarizes immunogenicity data from 30 publications regarding the use of PCV13 comprising 2406 individuals considered at high risk for IPD by the ACIP. Although antibody responses to PCV13 in individuals with immunocompromising and high-risk conditions were variable and generally lower compared with healthy controls, the vaccine was immunogenic and was largely well tolerated. Based on these findings, concerns regarding immunogenicity and safety of PCV13 are not supported and should not be barriers to vaccination in high-risk populations.

Streptococcus pneumoniae Nasopharyngeal Carriage among PCV-10-Vaccinated HIV-1-Infected Children with Maintained Serological Memory in Ethiopia

Streptococcus pneumoniae (S. pneumoniae) vaccines have substantially reduced the burden of invasive pneumococcal diseases (IPDs) worldwide. Despite high coverage with S. pneumoniae vaccination, upper-respiratory-tract colonization by S. pneumoniae is still common. We assessed maintenance of serological responses to S. pneumoniae serotypes included in PCV-10 by ELISA in HIV-1-infected children (n = 50) and age-matched controls (n = 50) in Ethiopia. We isolated S. pneumoniae in nasopharyngeal swabs and determined S. pneumoniae serotype by whole genome sequencing (WGS). Comparable levels of S. pneumoniae serotype-specific IgG concentrations were detected in plasma of HIV-1-infected children and matched controls, with geometric mean concentrations (GMCs) consistently higher than the protective threshold for PCV-10 serotypes of 0.35 μg/mL. We isolated S. pneumoniae from 38 (out of 97) nasopharyngeal swabs, 25 from HIV-1-infected children and 13 from controls. WGS based serotyping revealed 22 known S. pneumoniae serotypes and 2 nontypeable (NT) isolates. Non-PCV-10 serotypes represented >90% of isolates. We showed that HIV-1-infected children and matched controls in Ethiopia carry a level of maintained serological memory to PCV-10 considered protective for IPDs. We identified a higher proportion of nasopharyngeal carriage with highly pathogenic S. pneumoniae non-PCV strains among HIV-1-infected children compared to controls.

Streptococcus pneumoniae Acquisition and Carriage in Vaccine Naïve Indian Children with HIV and their Parents: A Longitudinal Household Study

OBJECTIVES

To investigate the difference in pneumococcal carriage, acquisition, antibiotic resistance profiles and serotype distribution, in human immunodeficiency virus (HIV) affected and unaffected families.

METHODS

A prospective cohort study was conducted in children with and without HIV in West Bengal from March 2012 through August 2014, prior to 13-valent pneumococcal conjugate vaccine (PCV-13) immunization. One thousand four hundred forty one nasopharyngeal swabs were collected and cultured at five-time points from children and their parents for pneumococcal culture, and serotyping by Quellung method.

RESULTS

One hundred twenty five HIV infected children and their parents, and 47 HIV uninfected children and their parents participated. Two hundred forty pneumococcal isolates were found. In children under 6 y, the point prevalence of colonization was 31% in children living with HIV (CLH) and 32% in HIV uninfected children (HUC), p = 0.6. The most common vaccine type (VT) serotypes were 6A, 6B and 19A. All isolates from parents and 71% from children in the HIV uninfected cohort were PCV-13 representative, compared to 33% of isolates from CLH and their parents. Acquisition rate in children was 1.77 times that of parents (OR = 1.77, 95%CI: 1.18-2.65). The HIV status of child or parent did not affect acquisition. Isolates from CLH were more frequently resistant to multiple antibiotics (p = 0.02).

CONCLUSIONS

While the rate of pneumococcal carriage and acquisition did not differ between CLH and HUC, HIV affected families had exposure to a wider range of serotypes including non-vaccine type serotypes and antibiotic resistant serotypes, than HIV unaffected families.

Long-Term Serological Response to 13-Valent Pneumococcal Conjugate Vaccine Versus 23-Valent Polysaccharide Vaccine in HIV-Infected Adults

INTRODUCTION

Long-term comparative immunologic response to 13-valent pneumococcal conjugate vaccine (PCV13) versus 23-valent polysaccharide vaccine (PPV23) among HIV-infected adults has not yet been investigated.

METHODS

In this prospective pilot study, we quantified in HIV-positive adults serotype-specific IgG concentrations of the 12 pneumococcal serotypes shared by both vaccines 5 years after vaccination with two doses of PCV13 8 weeks apart (group 1) or one dose of PPV23 (group 2) and compared them with those assessed prior to vaccination (BL) and after 1 year (T1). Comparison of immunogenicity was based on geometric mean concentration (GMC), proportion of individuals with ≥ twofold increase from BL in specific antibody concentration against ≥ 2 serotypes and percentage of individuals with serotype-specific IgG ≥ 0.35 μg/ml, ≥ 1 μg/ml and ≥ individual serotype-specific correlates of protection.

RESULTS

We included 91 subjects (median CD4+ 650 cells/µl, > 90% with HIV-RNA < 50 copies/ml); patients in groups 1 (n = 42) and 2 (n = 49) were homogeneous for the main characteristics. GMCs were significantly higher in the PCV13 group than in the PPV23 group for serotype 19F (p = 0.003). Both vaccines revealed higher significant GMCs to most serotypes compared with BL, i.e., eight in group 1 vs. seven in group 2. With respect to T1, GMCs decreased significantly in the PCV13 group for eight vs. ten serotypes in the PPV23 group. More participants in the PCV13 group had ≥ 2 increase from BL in antibody levels to ≥ 2 serotypes compared with the PPV23 group (78.6% vs. 59.2%, p = 0.042). Overall, the percentage of subjects with serotype-specific IgG ≥ 0.35 μg/ml, ≥ 1 μg/ml and ≥ individual serotype-specific correlates of protection was similar between groups.

CONCLUSION

In this study with HIV-positive adults with a favorable viro-immunologic profile, both vaccines were shown to achieve a long-term durable serologic response. We found minor differences in immunogenicity between the two vaccines, which favored PCV13 over PPV23 5 years after immunization.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT02123433.

Effectiveness of pneumococcal conjugate vaccination against invasive pneumococcal disease among children with and those without HIV infection: a systematic review and meta-analysis

Background

HIV-infected children are at a higher risk of Invasive Pneumococcal Disease (IPD) and its mortality, even in the era of antiretroviral therapy. Therefore, an effective vaccination strategy would be beneficial. To investigate the effectiveness of Pneumococcal Conjugate Vaccination (PCV) against IPD among HIV-Infected and HIV-Uninfected Children through a systematic review and meta-analysis.

Methods

Observational studies and randomized trials on 7 years old or older children were searched in the Cochrane Library, Web of Science core collection, Embase, Medline/PubMed, and Google Scholar. Critical appraisal was done using the Cochrane risk of bias tool and the Newcastle-Ottawa quality assessment form. Effectiveness and efficacy of at least one dose of PCV was investigated among children with and without HIV considering subgroups of pneumococcal serotypes. We meta-analyzed the effect sizes using random-effects modeling.

Results

Efficacy of PCV was estimated as 45.0% (31.2, 56.1) and 52.6% (25.7, 69.8) among HIV-infected and HIV-uninfected children, respectively. Effectiveness of PCV among HIV-infected children as − 6.2% (− 67.6, 32.7) was significantly lower than HIV-uninfected children 65.1% (47.3, 76.9). Effectiveness of PCV among HIV-infected children for IPDs caused by vaccine serotypes was estimated as 7.7(− 66.7, 48.9), and for IPDs caused by non-vaccine serotypes was estimated as − 402.8(− 1856, − 29.2).

Conclusion

Unlike the evidence on the efficacy of PCV against IPD among both of HIV-infected and HIV-uninfected children, its effectiveness against IPD among HIV-infected children is much less limited.

Review registration

The study protocol was registered at PROSPERO (registration ID: CRD42018108187).

Electronic supplementary material

The online version of this article (10.1186/s12879-019-4325-4) contains supplementary material, which is available to authorized users.

Current antimicrobial management of community-acquired pneumonia in HIV-infected children

INTRODUCTION

Community-acquired pneumonia is a leading cause of morbidity and mortality amongst HIV-infected infants and children. Polymicrobial infection is common and, due to the difficulties in confirming the etiology of pneumonia, empiric broad-spectrum antimicrobial therapy is frequently used.

AREAS COVERED

The author based this article on literature identified from PubMed. The author's search terms included: pneumonia, community-acquired pneumonia, HIV, children. The articles reviewed included original studies, recent review articles and current guidelines on the management of pneumonia in HIV-infected children. The microbiological etiology and the empiric and pathogen-specific antimicrobial therapy of community-acquired pneumonia in HIV-infected and HIV-exposed infants and children are also discussed.

EXPERT OPINION

There are many changing epidemiological factors impacting antimicrobial management of community-acquired pneumonia in the context of HIV infection in infants and children. These include vaccination strategies, antimicrobial prophylaxis, emerging drug-resistant pathogens, and recognition of the importance of viruses and tuberculosis in the etiology of community-acquired pneumonia. Further research is needed on optimal amtimicrobial management strategies in HIV-exposed uninfected children, and HIV-infected children receiving antiretroviral therapy.

The Pneumococcus and Its Critical Role in Public Health

Streptococcus pneumoniae is one of the commonest bacteria that cause morbidity and mortality in children and the elderly. The two extremes of age and individuals with underlying disease are particularly at risk of developing pneumococcal disease. The pneumococcus is responsible for a wide range of infectious diseases, ranging from mild, non-invasive infections such as otitis media and sinusitis, to more severe infections including pneumonia, septicemia, and meningitis. Despite the licensure of highly effective pneumococcal conjugate vaccines, the control of pneumococcal disease is still challenging. Here we describe the critical role of Streptococcus pneumoniae in public health.

Nasopharyngeal Pneumococcal Colonization and Impact of a Single Dose of 13-Valent Pneumococcal Conjugate Vaccine in Indian Children With HIV and Their Unvaccinated Parents

BACKGROUND

Human immunodeficiency virus (HIV) infection increases risk of invasive disease from Streptococcus pneumoniae. Pneumococcal conjugate vaccines (PCV) prevent invasive disease and acquisition of vaccine type (VT) pneumococcus in the nasopharynx.

OBJECTIVE

To look at the safety and impact of one dose of PCV13 on acquisition of VT pneumococcal carriage in Indian children with HIV.

METHOD

We conducted a cohort study in families of HIV-infected children (CLH) and families of HIV-uninfected children (HUC) in West Bengal. All children received one dose of PCV13. Nasopharyngeal swabs were collected from children and parents at baseline and 2 months after vaccination.

RESULT

One hundred and fifteen CLH and 47 HUC received one dose of PCV13. Fifty-eight percent of CLH were on antiretroviral therapy (ART), and the median nadir CD4 count was 287. There were no significant adverse events in either group. HUC had more VT colonization than CLH-55% versus 23% of all pneumococcal isolates. HIV infection doubled the risk of nonvaccine serotype colonization (P = 0.03). There was no difference in acquisition of VT isolates in CLH (4.4%) and HUC (4.5%) post-PCV13; however, older CLH (>5 years) had decreased clearance of VT strains. ART made no difference in pneumococcal colonization at baseline or after PCV13; however, CLH with higher nadir CD4 counts before starting ART were less likely to have VT colonization post-PCV13 (prevalence ratio, 0.2; 95% confidence interval: 0.1-0.5).

CONCLUSION

While there was no difference in acquisition of VT nasopharyngeal carriage of pneumococcus in CLH and HUC after one dose of PCV13, earlier access to ART may impact response to PCV13 in CLH.

Nasopharyngeal carriage of Streptococcus pneumoniae among HIV-infected and -uninfected children <5 years of age before introduction of pneumococcal conjugate vaccine in Mozambique

Nasopharyngeal carriage is a precursor for pneumococcal disease and can be useful for evaluating pneumococcal conjugate vaccine (PCV) impact. We studied pre-PCV pneumococcal carriage among HIV-infected and -uninfected children in Mozambique. Between October 2012 and March 2013, we enrolled HIV-infected children age <5 years presenting for routine care at seven HIV clinics in 3 sites, including Maputo (urban-south), Nampula (urban-north), and Manhiça (rural-south). We also enrolled a random sample of HIV-uninfected children <5 years old from a demographic surveillance site in Manhiça. A single nasopharyngeal swab was obtained and cultured following enrichment in Todd Hewitt broth with yeast extract and rabbit serum. Pneumococcal isolates were serotyped by Quellung reaction and multiplex polymerase chain reaction. Factors associated with pneumococcal carriage were examined using logistic regression. Overall pneumococcal carriage prevalence was 80.5% (585/727), with similar prevalences among HIV-infected (81.5%, 339/416) and HIV-uninfected (79.1%, 246/311) children, and across age strata. Among HIV-infected, after adjusting for recent antibiotic use and hospitalization, there was no significant association between study site and colonization: Maputo (74.8%, 92/123), Nampula (83.7%, 82/98), Manhiça (84.6%, 165/195). Among HIV-uninfected, report of having been born to an HIV-infected mother was not associated with colonization. Among 601 pneumococcal isolates from 585 children, serotypes 19F (13.5%), 23F (13.1%), 6A (9.2%), 6B (6.2%) and 19A (5.2%) were most common. The proportion of serotypes included in the 10- and 13-valent vaccines was 44.9% and 61.7%, respectively, with no significant differences by HIV status or age group. Overall 36.9% (n = 268) of children were colonized with a PCV10 serotype and 49.7% (n = 361) with a PCV13 serotype. Pneumococcal carriage was common, with little variation by geographic region, age, or HIV status. PCV10 was introduced in April 2013; ongoing carriage studies will examine the benefits of PCV10 among HIV-infected and–uninfected children.

Survival of HIV-1 vertically infected children

PURPOSE OF REVIEW

It is 20 years since the start of the combination antiretroviral therapy (cART) era and more than 10 years since cART scale-up began in resource-limited settings. We examined survival of vertically HIV-infected infants and children in the cART era.

RECENT FINDINGS

Good survival has been achieved on cART in all settings with up to 10-fold mortality reductions compared with before cART availability. Although mortality risk remains high in the first few months after cART initiation in young children with severe disease, it drops rapidly thereafter even for those who started with advanced disease, and longer term mortality risk is low. However, suboptimal retention on cART in routine programs threatens good survival outcomes and even on treatment children continue to experience high comorbidity risk; infections remain the major cause of death. Interventions to address infection risk include a cotrimoxazole prophylaxis, isoniazid preventive therapy, routine childhood and influenza immunization, and improving maternal survival.

SUMMARY

Pediatric survival has improved substantially with cART and HIV-infected children are aging into adulthood. It is important to ensure access to diagnosis and early cART, good program retention as well as optimal comorbidity prophylaxis and treatment to achieve the best possible long-term survival and health outcomes for vertically infected children.

Bloodstream infections in HIV-infected patients

In the combined antiretroviral therapy era, HIV-infected patients remain a vulnerable population for the onset of bloodstream infections (BSI). Worldwide, nontyphoid salmonellae, Streptococcus pneumoniae, Escherichia coli, Staphylococcus aureus and coagulase negative staphylococci are the most important pathogens. Intravenous catheter associated infection, skin-soft tissue infection and endocarditis are associated with Gram-positive bacteremia. Among the Gram-negative, nontyphoidal Salmonella have been previously correlated to sepsis. Other causes of BSI in HIV-infected patients are mycobacteria and fungi. Mycobacteria constitute a major cause of BSI in limited resource countries. Fungal BSI are not frequent and among them Cryptococcus neoformans is the most common life-threatening infection. The degree of immunosuppression remains the key prognostic factor leading to the development of BSI.

Tuberculosis and pneumonia in HIV-infected children: an overview

Pneumonia remains the most common cause of hospitalization and the most important cause of death in young children. In high human immunodeficiency virus (HIV)-burden settings, HIV-infected children carry a high burden of lower respiratory tract infection from common respiratory viruses, bacteria and Mycobacterium tuberculosis. In addition, Pneumocystis jirovecii and cytomegalovirus are important opportunistic pathogens. As the vertical transmission risk of HIV decreases and access to antiretroviral therapy increases, the epidemiology of these infections is changing, but HIV-infected infants and children still carry a disproportionate burden of these infections. There is also increasing recognition of the impact of in utero exposure to HIV on the general health of exposed but uninfected infants. The reasons for this increased risk are not limited to socioeconomic status or adverse environmental conditions—there is emerging evidence that these HIV-exposed but uninfected infants may have particular immune deficits that could increase their vulnerability to respiratory pathogens. We discuss the impact of tuberculosis and other lower respiratory tract infections on the health of HIV-infected infants and children.

Impact of Haemophilus influenzae Type B Conjugate Vaccines on Nasopharyngeal Carriage in HIV-infected Children and Their Parents From West Bengal, India

BACKGROUND

In addition to reducing Haemophilus influenzae type b (Hib) disease in vaccinated individuals, the Hib conjugate vaccine (HibCV) has indirect effects; it reduces Hib disease in unvaccinated individuals by decreasing carriage. Human immunodeficiency virus (HIV)-infected children are at increased risk for Hib disease and live in families where multiple members may have HIV. The aim of this study is to look at the impact of 2 doses of the HibCV on nasopharyngeal carriage of Hib in HIV-infected Indian children (2-15 years) and the indirect impact on carriage in their parents.

METHODS

This prospective cohort study was conducted in HIV-infected and HIV-uninfected families. Nasopharyngeal swabs were collected from children and parents before and after vaccination. HIV-infected children 2-15 years of age got two doses of HibCV and were followed up for 20 months. Uninfected children 2-5 years of age got 1 dose of HibCV as catch-up.

RESULTS

123 HIV-infected and 44 HIV-uninfected children participated. Baseline colonization in HIV-infected children was 13.8% and dropped to 1.8% (P = 0.002) at 20 months. Baseline carriage in HIV-uninfected children was 4.5% and dropped to 2.3% after vaccination (P = 0.3). HIV-infected parents had 12.3 times increased risk of Hib carriage if their child was colonized (P = 0.04) and had 9.3 times increased risk if their child had persistent colonization postvaccine (P = 0.05). No parent of HIV-uninfected children had Hib colonization at any point. Pneumococcal colonization was associated with increased Hib colonization.

CONCLUSION

Making the HibCV available to HIV-infected children could interrupt Hib carriage in high-risk families.

Immunogenicity and safety of the 13-valent pneumococcal conjugate vaccine in HIV-infected individuals naive to pneumococcal vaccination

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Objective:

Immunocompromised individuals are at an increased risk of pneumococcal disease. Vaccination is recommended as an important strategy to reduce risk of pneumococcal disease in HIV-infected individuals. This study evaluated the safety and immunogenicity of three 13-valent pneumococcal conjugate vaccine (PCV13) doses followed by one dose of 23-valent pneumococcal polysaccharide vaccine (PPSV23) at 1-month intervals in pneumococcal vaccine-naive, HIV-infected individuals.

Design:

This was a phase 3, open-label, single-arm study.

Methods:

Pneumococcal vaccine-naive, HIV-infected individuals at least 6 years of age with CD4⁺ T-cell count at least 200 cells/μl and viral load less than 50 000 copies/ml received three doses of PCV13 followed by one dose of PPSV23 at 1-month intervals. Serotype-specific antipneumococcal immune responses were assessed by IgG geometric mean concentrations (GMCs) and opsonophagocytic activity (OPA) assay geometric mean titres (GMTs) after each dose. Local reactions at the PCV13 injection site, systemic and other adverse events were collected.

Results:

Three hundred and one individuals were enrolled and vaccinated; 279 completed the study. Statistically significant increases in IgG GMCs and OPA GMTs were observed for all serotypes after dose 1 of PCV13 compared with prevaccine levels. GMCs and GMTs were comparable or only modestly increased for all serotypes after PCV13 doses 2 and 3 and after PPSV23. The majority of local reactions and systemic events were mild to moderate in severity.

Conclusion:

A three-dose regimen of PCV13 was well tolerated in pneumococcal vaccine-naive, HIV-infected individuals. Significant immune responses to all serotypes were observed following the first dose of PCV13, with only modest increases in antibody titres following subsequent PCV13 or PPSV23 administration.

Immunogenicity of the Bivalent Oral Cholera Vaccine Shanchol in Haitian Adults With HIV Infection

We evaluated immune responses following bivalent oral cholera vaccination (Shanchol [Shantha Biotechnics]; BivWC) in a cohort of 25 human immunodeficiency virus (HIV)-infected adults in Haiti. Compared with adults without HIV infection, vaccination in HIV-infected individuals resulted in lower vibriocidal responses against Vibrio cholerae O1, and there was a positive relationship between the CD4(+) T-cell count and vibriocidal responses following vaccination. Nevertheless, seroconversion occurred at a rate of 65% against the Ogawa serotype and 74% against the Inaba serotype in adults with HIV infection. These results suggest that the vaccine retains substantial immunogenicity in adults with HIV infection and may benefit this population by protecting against cholera.

Immunogenicity and Safety of 13-Valent Pneumococcal Conjugate Vaccine in HIV-Infected Adults Previously Vaccinated With Pneumococcal Polysaccharide Vaccine

BACKGROUND

Persons with human immunodeficiency virus (HIV) infection are at increased risk of pneumococcal disease. We evaluated the safety and immunogenicity of 13-valent pneumococcal conjugate vaccine (PCV13) in this population.

METHODS

HIV-infected persons ≥ 18 years of age who were previously vaccinated with ≥ 1 dose of 23-valent pneumococcal polysaccharide vaccine (PPSV23) and had CD4 cell counts ≥ 200 cells/mm(3) and HIV viral loads <50 000 copies/mL were enrolled in this 3-dose PCV13 open-label study.

RESULTS

A total of 329 subjects received ≥ 1 dose, and 279 received 3 doses administered at 6-month intervals. Increases in anticapsular polysaccharide immunoglobulin G concentrations and opsonophagocytic antibody titers were demonstrated 1 month after each of the 3 doses of PCV13. Antibody levels were generally similar after each dose. The responses were similar whether subjects had previously received 1 or ≥ 2 doses of PPSV23. Pain at the injection-site was the most common local reaction. Severe injection site or systemic events were uncommon.

CONCLUSIONS

Vaccination with PCV13 induces anticapsular immunoglobulin G and opsonophagocytic antibody responses in HIV-infected adults with prior PPSV23 vaccination and CD4 cell counts ≥ 200 cells/mm(3). The observations support the use of PCV13 in this population.

CLINICAL TRIALS REGISTRATION

NCT00963235.

Serotype distribution and antibiotic susceptibility of Streptococcus pneumoniae strains carried by children infected with human immunodeficiency virus

Background

We studied the serotype distribution and antibiotic susceptibility of Streptococcus pneumoniae isolates carried by children infected with HIV in Jakarta, Indonesia.

Methods

Nasopharyngeal swabs were collected from 90 HIV infected children aged 4 to 144 months. S. pneumoniae was identified by conventional and molecular methods. Serotyping was performed with sequential multiplex PCR and antibiotic susceptibility with the disk diffusion method.

Results

We identified S. pneumoniae carriage in 41 children (46%). Serotype 19F was most common among 42 cultured strains (19%) followed by 19A and 6A/B (10% each), and 23F (7%). Most isolates were susceptible to chloramphenicol (86%), followed by clindamycin (79%), erythromycin (76%), tetracycline (43%), and sulphamethoxazole/trimethoprim (41%). Resistance to penicillin was most common with only 33% of strains being susceptible. Strains of serotypes targeted by the 13-valent pneumococcal conjugate polysaccharide vaccine (PCV13) were more likely to be multidrug resistant (13 of 25 or 52%) compared to non-PCV13 serotype isolates (3 of 17 or 18%; Fisher exact test p = 0.05).

Conclusion

Our study provides insight into the epidemiology of pneumococcal carriage in young HIV patients in Indonesia. These findings may facilitate potential preventive strategies that target invasive pneumococcal disease in Indonesia.

Maternal pneumococcal capsular IgG antibodies and transplacental transfer are low in South Asian HIV-infected mother-infant pairs

BACKGROUND

Our understanding of the mother-to-child transfer of serotype-specific pneumococcal antibodies is limited in non-immunized, HIV-positive women.

METHODS

We compared geometric mean antibody concentrations (GMCs), geometric mean transplacental cord:maternal ratios (GMRs) and proportions of samples with protective antibody concentration (≥0.35μg/ml) to serotypes 1, 4, 5, 6B, 9V, 14, 18C, 19F, 23F between 74 HIV-infected and 98 HIV-uninfected mother-infant pairs who had not received pneumococcal immunization in South Asia. Multivariable analysis was performed to assess the influence of HIV on protective antibody concentrations.

RESULTS

HIV-infected mothers and their infants exhibited lower GMCs and GMRs than their uninfected counterparts. This was significant for all serotypes except maternal GMC to serotype 1 and GMR for serotype 6B. In multivariate analysis, HIV was significantly associated with reduced odds of having protective pneumococcal IgG levels; 56-73% reduction for 3 maternal serotypes (4, 5, 23F) and 62-90% reduction for all cord samples except serotype 6B.

CONCLUSIONS

Maternal HIV infection is associated with lower levels of maternal pneumococcal antibodies and disproportionately lower cord antibodies, relative to maternal antibodies, suggesting that HIV infection compromises transplacental transfer. Reassessment of maternal and/or infant pneumococcal immunization strategies is needed in HIV-infected women and their infants.

Pneumococcal immunization in immunocompromised hosts: where do we stand?

Immunocompromised patients are all at risk of invasive pneumococcal disease, of different degrees and timings. However, considerable progress in pneumococcal immunization over the last 30 years should benefit these patients. The 23-valent polysaccharide vaccine has been widely evaluated in these populations, but due to its low immunogenicity, its efficacy is sub-optimal, or even low. The principle of the conjugate vaccine is that, through the protein conjugation with the polysaccharide, the vaccine becomes more immunogenic, T-cell dependent, and thus providing a better early response and a boost effect. The 7-valent conjugate vaccine has been the first one to be evaluated in different immunocompromised populations. We review here the efficacy and safety of the different antipneumococcal vaccines in cancer, transplant and HIV-positive patients and propose a critical appraisal of the current guidelines.

Understanding the contribution of common childhood illnesses and opportunistic infections to morbidity and mortality in children living with HIV in resource-limited settings

OBJECTIVE

Although antiretroviral treatment (ART) has reduced the incidence of HIV-related opportunistic infections among children living with HIV, access to ART remains limited for children, especially in resource-limited settings. This paper reviews current knowledge on the contribution of opportunistic infections and common childhood illnesses to morbidity and mortality in children living with HIV, highlights interventions known to improve the health of children, and identifies research gaps for further exploration.

DESIGN AND METHODS

Literature review of peer-reviewed articles and abstracts combined with expert opinion and operational experience.

RESULTS

Morbidity and mortality due to opportunistic infections has decreased in both developed and resource-limited countries. However, the burden of HIV-related infections remains high, especially in sub-Saharan Africa, where the majority of HIV-infected children live. Limitations in diagnostic capacity in resource-limited settings have resulted in a relative paucity of data on opportunistic infections in children. Additionally, the reliance on clinical diagnosis means that opportunistic infections are often confused with common childhood illnesseswhich also contribute to excess morbidity and mortality in these children. Although several preventive interventions have been shown to decrease opportunistic infection-related mortality, implementation of many of these interventions remains inconsistent.

CONCLUSIONS

In order to reduce opportunistic infection-related mortality, early ART must be expanded, training for front-line clinicians must be improved, and additional research is needed to improve screening and diagnostic algorithms.

Antibody persistence and immunologic memory after sequential pneumococcal conjugate and polysaccharide vaccination in HIV-infected children on highly active antiretroviral therapy

BACKGROUND

The capacity of pneumococcal vaccination to confer memory in HIV-infected children is critical for durable protection.

METHODS

HIV-infected children 2-<19 years administered two doses of pneumococcal conjugate vaccine (PCV7) and one dose of polysaccharide vaccine (PPV) on HAART were randomized 4-5 years later to receive a PCV7 or PPV booster. Total and high avidity antibodies to serotypes 1 (PPV) and 6B and 14 (PCV7 and PPV) were determined by ELISA. Memory was defined as persistence of ≥ 0.5 mcg/mL of serotype-specific antibody on day 0 or change from <0.5 mcg/mL to ≥ 0.5 mcg/mL between day 0 and week 1, or, ≥ 4-fold antibody rise between day 0 and week 1.

RESULTS

Prior to boosting, 4-5 years after the previous PCV7-PCV7-PPV series, geometric mean concentrations (GMCs) were 0.46 mcg/mL (serotype 1), 1.31 mcg/mL (serotype 6B), and 1.47 mcg/mL (serotype 14), with concentrations ≥ 0.5 mcg/mL in 41% (serotype 1) to 82% (serotypes 6B and 14). Memory based on antibody concentration ≥ 0.5 mcg/mL before or 1 week after boosting with PCV7 or PPV was demonstrated in 42-61% for serotype 1 and 87-94% for serotypes 6B and 14, with lower rates based on day 0 to week 1 ≥ 4-fold antibody rise (serotype 1, 3-13%; serotype 6B, 13-31%; serotype 14, 29-53%). Antibody concentrations post-boosting were greater following PCV7 than PPV for serotypes 6B and 14. Ratios of highly avid to total antibody pre- and post-boosting were 0.5-0.8. Predictors of memory included higher CD4% (nadir before HAART and at P1024 and P1061s entry), CD19% (at P1024 and P1061s entry), and antibody response after the PCV7-PCV7-PPV primary series and lower viral load (at P1024 and P1061s entry) and age.

CONCLUSIONS

Protective antibody concentrations, high avidity, and booster responses to PCV7 or PPV indicative of memory were present 4-5 years after PCV7-PCV7-PPV in HIV-infected children on HAART.

HIV and influenza virus infections are associated with increased blood pneumococcal load: a prospective, hospital-based observational study in South Africa, 2009-2011

BACKGROUND

Increased pneumococcal loads are associated with severe outcomes. We determined the prevalence of pneumococcal DNA in blood specimens from patients hospitalized with acute lower respiratory tract infection and identified factors associated with invasive pneumococcal pneumonia, bacterial loads, and death.

METHODS

A total of 8523 patients were enrolled as part of prospective hospital-based surveillance. Blood was collected for quantitative pneumococcal (lytA) detection, and nasopharyngeal specimens were collected for detection of influenza virus and other respiratory viruses by real-time polymerase chain reaction.

RESULTS

Of 6396 cases (75%) with lytA results, 422 (7%) were positive for pneumococcal DNA. The prevalences of human immunodeficiency virus (HIV) and influenza virus were 51% (2965/5855) and 8% (485/6358), respectively. On multivariable analysis, HIV infection (adjusted odds ratio [aOR], 2.4; 95% confidence interval [CI], 1.6-3.6), influenza virus coinfection (aOR, 1.4; 95% CI, 1.2-2.1), oxygen therapy during admission (aOR, 1.6; 95% CI, 1.1-2.3) and in-hospital death (aOR, 2.1; 95% CI, 1.1-4.0) were significantly associated with increased pneumococcal load. Among lytA-positive patients, after adjustment for length of hospitalization, duration of symptoms, and oxygen therapy during admission, pneumococcal loads ≥10,000 DNA copies/mL (aOR, 3.6; 95% CI, 1.8-7.2) were associated with increased risk of death.

CONCLUSIONS

HIV and influenza virus infections were associated with elevated pneumococcal loads, which, in turn, were associated with increased risk of death.

Use of the 13-valent pneumococcal conjugate vaccine in children and adolescents aged 6 - 17 years

INTRODUCTION

The introduction of pneumococcal conjugate vaccines into infant immunization schedules has successfully reduced the incidence of pneumococcal disease caused by vaccine serotypes. Disease incidence is low in healthy 6 - 17-year-old children and young people; however, there are a number of clinical conditions that put individuals in this age group at increased risk. Expansion of the license of a 13-valent pneumococcal conjugate vaccine , PCV-13, to include the 6 - 17 age group has recently been approved by European and American regulatory bodies.

AREAS COVERED

Studies assessing the safety, immunogenicity, and efficacy of pneumococcal conjugate vaccines in both healthy and high-risk 6 - 17-year-old children and adolescents are covered and the potential impact of PCV-13 in these populations is discussed. The use of the 23-valent pneumococcal polysaccharide vaccine, PPV-23, in high-risk children and adolescents is also considered.

EXPERT OPINION

Expanding the use of PCV-13 to include high-risk children and adolescents aged 6 - 17 has the potential to prevent additional cases of disease; however, vaccination of this population may no longer be necessary when herd immunity to PCV-13 serotypes becomes fully established. Despite the broader serotype coverage of PPV-23, the benefits of this vaccine in high-risk populations are uncertain.

Epidemiology of invasive pneumococcal disease and vaccine provision in a tertiary referral center

Invasive pneumococcal disease (IPD) has an all-cause mortality of 5-35 % in the developed world. Pneumococcal vaccination is recommended for at-risk groups, including those infected with human immunodeficiency virus (HIV) and those over 65 years of age. However, adherence to vaccination guidelines is low. We reviewed all cases of IPD in our tertiary referral hospital from 2006 to 2010. IPD was defined as the isolation of Streptococcus pneumoniae from a normally sterile site with a compatible clinical syndrome. Demographics, risk factors, susceptibilities, pneumococcal serotype, mortality, and vaccination status for each patient were analyzed. There were 127 IPD episodes in 122 patients. The overall case fatality rate was 21.2 %. Seventy-two percent of the patients had two or more risk factors that should have prompted pneumococcal vaccination. However, the overall pneumococcal vaccination provision was only 9 %: 64.6 % of all typed isolates were contained in the pneumococcal polysaccharides vaccine 23 (PPV23), 48.8 % in the 7-valent pneumococcal conjugate vaccine (PCV7), and 60.1 % in PCV13. All isolates were fully sensitive to penicillin and cefotaxime. Recurrent IPD was seen in 11 % of the HIV-infected patients, highlighting a particular at-risk group. IPD has a high mortality rate. There is low vaccine provision in our study, although most IPD patients had risk factors that should have prompted vaccination. HIV-positive people are particularly at risk; vaccinating those with persisting CD4 counts less than 200 cells/mm(3) and the use of "prime-boost" strategies may decrease incidence in the future. Newer models of care such as a dedicated vaccine clinic as described in this study may help increase vaccine provision and uptake.

Risk factors for death and severe sequelae in Malawian children with bacterial meningitis, 1997-2010

BACKGROUND

Acute bacterial meningitis (ABM) causes significant death and disability in children worldwide, with HIV recognized as an established risk factor for infection and negative outcomes. However, additional major risk factors for death and disability in pediatric ABM remain unclear.

METHODS

We conducted a retrospective analysis of case data from 3 departmental studies of ABM involving 1784 children <15 years old who attended Queen Elizabeth Central Hospital in Blantyre, Malawi during 1997 to 2010. Univariate and multivariate logistic regression models were used to estimate the effects of HIV seropositivity, impaired consciousness and causative organism on death and severe sequelae.

RESULTS

Impaired consciousness or coma at the time of admission was strongly associated with death (coma: odds ratio [OR] = 14.4, 95% confidence interval [CI]: 9.42, 22.1) and severe sequelae (Coma: OR = 3.27, 95% CI: 2.02, 5.29) in multivariate logistic regression models. HIV seropositivity was significantly associated with increased odds of death (OR = 1.65, 95% CI: 1.20, 2.26) but not with developing severe sequelae (OR = 0.88, 95% CI: 0.56, 1.38). After adjustment, infection with Salmonella spp. was associated with increased odds of death (OR = 2.11, 95% CI: 1.06, 4.08) and pneumococcal meningitis was associated with increased odds of severe sequelae (OR = 1.84, 95% CI: 1.03, 3.29).

CONCLUSIONS

Impaired consciousness and HIV infection increased the odds of death from ABM in Malawian children. Use of pneumococcal conjugate vaccine could greatly reduce the burden of ABM in Malawi.

Dynamics of nasopharyngeal bacterial colonisation in HIV-exposed young infants in Tanzania

OBJECTIVES

To estimate the prevalence of nasopharyngeal bacterial colonisation (NPBC) patterns in young Tanzanian HIV-exposed infants and to analyse the influence of maternal NPBC and of the infant's HIV status on the NPBC pattern.

METHODS

Longitudinal cohort study of neonates born to HIV-infected mothers visiting Kilimanjaro Christian Medical Centre, Tanzania, between 2005 and 2009. Demographic and clinical data and nasopharyngeal bacterial cultures were obtained at the age of 6 weeks, 3 and 6 months, and at one time point, a paired mother-infant nasopharyngeal swab was taken.

RESULTS

Four hundred and twenty-two swabs were taken from 338 eligible infants. At 6 weeks of age, colonisation rates were 66% for Staphylococcus aureus, 56% for Streptococcus pneumoniae, 50% for Moraxella catarrhalis and 14% for Haemophilus influenzae. Colonisation with S. aureus diminished over time and was more common in HIV-infected infants. S. pneumoniae and H. influenzae colonisation rose over time and was more prevalent in HIV-uninfected children. Co-colonisation of S. pneumoniae with H. influenzae or M. catarrhalis was mostly noticed in HIV-infected infants. S. pneumoniae and M.catarrhalis colonisation of the mother was a risk factor for colonisation in HIV-uninfected infants, while maternal S. aureus colonisation was a risk factor for colonisation in HIV-infected infants. Among the 104 S. pneumoniae isolates, 19F was most prevalent, and 57 (55%) displayed capsular serotypes represented in the 13-valent pneumococcal conjugate vaccine.

CONCLUSIONS

NPBC was common in Tanzanian HIV-exposed infants. The significant prevalence of pneumococcal vaccine serotypes colonising this paediatric population justifies the use of the 13-valent pneumococcal vaccine to reduce the burden of pneumococcal invasive disease.

Serologic response to primary vaccination with 7-valent pneumococcal conjugate vaccine is better than with 23-valent pneumococcal polysaccharide vaccine in HIV-infected patients in the era of combination antiretroviral therapy

OBJECTIVES

The objectives of this study were to compare the serologic responses at week 48 to primary vaccination with 23-valent pneumococcal polysaccharide vaccine (PPV) vs. 7-valent pneumococcal conjugate vaccine (PCV); and to identify factors associated with serologic response in HIV-infected adult patients with access to combination antiretroviral therapy (cART).

METHODS

One hundred and four CD4-matched pairs of HIV-infected patients who underwent primary pneumococcal vaccination with 23-valent PPV or 7-valent PCV were enrolled for determinations of anti-capsular antibody responses against four serotypes (6B, 14, 19F and 23F) at baseline, 24 weeks and 48 weeks following vaccination. Significant antibody responses were defined as 2-fold or greater increase of antibody levels at week 48 compared with baseline. The logistic regression model was used to determine the factors associated with serologic response to at least one and two serotypes.

RESULTS

At week 48, patients who received PCV demonstrated a statistically significantly higher response rate to at least 2 serotypes than those who received PPV (37.5% vs. 20.2%, p = 0.006). In multivariate analysis, factors associated with significant antibody responses to at least one or two serotypes included receipt of PCV (adjusted odds ratio [AOR], 2.42 [95% CI, 1.23-4.78] and 3.58 [95% CI. 1.76-7.28], respectively), and undetectable plasma HIV RNA load (< 400 copies/ml) at vaccination (AOR, 1.47 [95% CI, 0.60-3.64] and 3.62 [95% CI, 1.11-11.81], respectively).

CONCLUSIONS

Primary vaccination with 7-valent PCV achieved a significantly better serologic responses to one or two out of the four serotypes studied at week 48 than with 23-valent PPV in HIV-infected patients in the cART era. Suppression of HIV replication when primary vaccination was administered was associated with better serologic responses.

Associations between potential bacterial pathogens in the nasopharynx of HIV infected children

OBJECTIVE

To investigate bacterial associations of S. pneumoniae, S. aureus, and H. influenzae in the nasopharynx of ambulatory children with HIV infection.

METHODS

A cross-sectional nasopharyngeal swab survey of 148 children with HIV infection from West Bengal presenting for routine outpatient care was conducted.

RESULTS

Forty-one (28 %) children carried S. pneumoniae, 35 (24 %) carried S. aureus and 39 (26 %) carried H. influenzae. Seventeen (11 %) had dual colonization with S. pneumoniae and H. influenzae, 13(8.8 %) had dual colonization with S. pneumoniae and S. aureus, and 6(4 %) had dual colonization with S. aureus and H. influenzae. Three (2 %) had triple carriage with H. influenzae, S. aureus, and S. pneumoniae. Neither Cotrimoxazole prophylaxis nor ART (antiretroviral therapy) affected colonization with any organism. There was no association between HIV immune status, recent antibiotic use, exposure to other children, household tuberculosis exposure and colonization with any organism. There was a strong negative association between malnutrition and colonization with H. influenzae.

CONCLUSIONS

The negative association between S. pneumoniae and S. aureus colonization in the nasopharynx described in healthy populations was not present. The authors found a strong positive association between carriage with H. influenzae and S. pneumoniae. These findings provide insight into the increased risk of invasive disease from these organisms in HIV infected children.

Acute exercise enhancement of pneumococcal vaccination response: a randomised controlled trial of weaker and stronger immune response

Acute exercise at the time of vaccination can enhance subsequent immune responses. However, the potential benefit of this effect will be its efficacy in boosting poor responses, and thus protection in at-risk populations. The current study tested the effect of exercise on the response to either a full- or half-dose Pneumococcal (Pn) vaccination to elicit stronger and weaker responses. Subjects were 133 young healthy adults, randomised to one of four groups: exercise or control task, receiving a full- or half-dose Pn vaccination. Prior to vaccination, exercise groups completed a 15 min arm and shoulder exercise task, control groups rested quietly. Antibody levels to 11 Pn strains were evaluated at baseline and 1-month. Across all participants, exercise groups showed significantly greater increase in antibody levels than control groups. When doses were compared, it emerged that those who exercised had significantly larger responses than those who rested in the half-dose group, but in the full-dose groups responses were similar. This data indicates the effectiveness of exercise as a vaccine adjuvant, particularly in weaker responses. Thus, given the potential public health benefits of no-cost behavioural intervention to enhance response to vaccination, testing in at-risk populations should be pursued.

Nasopharyngeal carriage of Streptococcus pneumoniae: prevalence and risk factors in HIV-positive children in Tanzania

BACKGROUND

Pneumococcal colonization of the nasopharynx is especially common in young children and is a pre-requisite for pneumococcal disease. Those with immunosuppression, such as HIV, are at higher risk of colonization and disease, especially at older ages. Currently, vaccination schedules are only offered to children under 6 months of age, despite the large impact of pneumococcal disease in older unvaccinated children with HIV. We conducted a study to assess the prevalence of, and risk factors for, pneumococcal carriage in HIV-positive children aged <15 years.

METHODS

We collected a single nasopharyngeal swab from 142 HIV-infected children aged 1-14 years over a 2-month period. To detect carriage of pneumococcus, these samples were cultured and serotyped; PCR was performed on negative samples. We also collected epidemiological data via survey and medical records.

RESULTS

The overall carriage rate was 81% and was at least 76% in those aged 5-14 years. The 7-, 10-, and 13-valent pneumococcal vaccines would cover 37%, 37%, and 49% of children with carriage, respectively. In the multivariate analysis, we identified increase in weight since last visit (p=0.028) and the existence of care-givers who had respiratory symptoms in the past week (p=0.022) as risk factors for carriage. Weight gain was also significantly associated with antiretroviral use (p=0.002).

CONCLUSIONS

These data illuminate the little known area of pneumococcal carriage in older HIV-infected children as well as finding novel risk factors for pneumococcal carriage, namely the association with household members who have respiratory symptoms and with an increase in the child's weight prior to swabbing. Weight gain may be due to an increase in health enabling more mobility and increasing the risk of acquiring carriage. The carriage rate observed (81%) is one of the highest recorded. Further research should address whether vaccination can prevent the acquisition of carriage and so protect against disease.

Epidemiology of acute osteoarticular sepsis in a setting with a high prevalence of pediatric HIV infection

BACKGROUND

There is limited information on osteoarticular infections in human immunodeficiency virus (HIV)-infected children. The purpose of this study was to determine the effect of HIV on the epidemiology of osteoarticular infections in a setting with a high prevalence of pediatric HIV infection.

METHODS

A retrospective evaluation of children presenting with acute septic arthritis or osteomyelitis from June 2005 to July 2009 was undertaken. Standard departmental protocols for the management of osteoarticular infections, including testing for HIV, were practised.

RESULTS

A total of 102 cases of acute septic arthritis or osteomyelitis were identified during the study period. These included 22 (21.6%) episodes in HIV-infected children, 66 (64.7%) in HIV-non-infected children, and 14 (13.7%) cases in whom the HIV status was unknown. The median age of children was 30.6 months (range, 9.2 to 82.9 mo) and did not differ by HIV status. Streptococcus pneumoniae was identified in 8 of 12 (66.7%) HIV-infected children compared with 3 (9.7%) of 31 HIV-non-infected children (P<0.001). Conversely, fewer episodes in HIV-infected children (4.8%) were associated with Staphylococcus aureus compared with HIV-non-infected children (24.6%; P=0.06). No patients died. Twelve cases required repeated surgical procedures.

CONCLUSIONS

Empirical management of osteoarticular infections in settings with a high prevalence of HIV-infected children or children known to be HIV infected needs to be tailored based on a higher proportion of episodes being due to S. pneumoniae in HIV-infected children.

CLINICAL RELEVANCE

Our results suggest that HIV-infected children with osteoarticular infections should be started on broader spectrum antibiotics before culture results are available.

LEVEL OF EVIDENCE

Level IV, diagnostic study.

Safety, immunogenicity and efficacy of pneumococcal conjugate vaccine in HIV-infected individuals

Streptococcus pneumoniae is the leading bacterial opportunistic infection in HIV-infected individuals. Anti-retroviral treatment (ART) of HIV-infected individuals reduces their risk of invasive pneumococcal disease (IPD), however, it remains 20- to 40-fold greater compared with age-matched general population. This review summarizes the available published data on the immunogenicity, safety and efficacy of pneumococcal polysaccharide-protein conjugate vaccines (PCV) in HIV-infected children and adults.   Several studies have demonstrated that PCV are safe in the HIV-infected persons. Although PCV are immunogenic in HIV-infected infants, the antibodies produced are functionally impaired, there is possibly a lack or loss of anamnestic responses and immunity declines in later life However, quantitative and qualitative antibody responses to PCV in HIV-infected infants are enhanced when vaccination occurs whilst on ART, as well as if vaccination occurs when the CD4+ cell percentage is ≥ 25% and if the nadir CD4+ is > 15%. Although the efficacy of PCV was lower, the vaccine preventable burden of hospitalization for IPD and clinical pneumonia were 18-fold and 9-fold greater, respectively, in HIV-infected children compared with -uninfected children. In HIV-infected adults, PCV vaccination induces more durable and functional antibody responses in individuals on ART at the time of vaccination than in ART-naive adults, independently of baseline CD4+ cell count, although there does not appear to be much benefit from a second-dose of PCV. PCV has also been shown to reduce the risk of recurrent IPD by 74% in HIV-infected adults not on ART, albeit, also with subsequent decline in immunity and protection.

Invasive pneumococcal disease among HIV-positive individuals, 2000-2009

OBJECTIVES

To examine invasive pneumococcal disease (IPD) incidence, the impact of the 7-valent pneumococcal conjugate vaccines (PCV7s) programme on the distribution of Streptococcus pneumoniae serotypes and risk factors for IPD among HIV-positive adults.

METHODS

We analysed adults (aged ≥15 years) reported to the HIV and IPD national datasets in England and Wales (2000-2009). Through data-linkage, changes in IPD incidence and serotype distribution were examined. Risk factors for IPD among HIV-positive adults were assessed using a case-control study.

RESULTS

Among 63,109 HIV-positive adults, 951 were co-infected with IPD. The average annual incidence of IPD was 245 episodes per 100,000 HIV-positive adults and 246 of 100,000 among those aged 15-44 years. Incidence was higher among those not on antiretroviral therapy (ART) (281 of 100,000) and those with severe immunosuppression (563 of 100,000). Among 9283 adults aged 15-44 at IPD diagnosis, 2.4% were living with undiagnosed HIV. The proportion of IPD episodes in HIV-positive adults with serotypes covered by PCV7 was 23% in 2009, a 54% proportional reduction compared with pre-PCV7 (2000-2006); the reduction in adults of unknown HIV status was 70%. The proportion of IPD episodes among HIV-positive adults caused by serotypes covered by PCV13 was 61%. Significant risk factors for IPD in multivariate analysis included older aged (≥65 years), a lower nadir CD4 cell count and no previous ART.

CONCLUSION

An HIV test should be offered and recommended to adults aged 15-44 years without other obvious IPD risk factors. Our study provides an evidence base to policy makers regarding the use of the new PCV13 in HIV-positive adults.

Role of IL-21 and IL-21 receptor on B cells in HIV infection

Interleukin (IL)-21 is a member of a family of cytokines that includes IL-2, IL-4, IL-7, IL-9, and IL-15, all of which utilize a common γ chain in their individual receptor complexes for delivering intracellular signals in their target cells. IL-21 is produced by CD4+ T-cells, in particular follicular T-helper cells, and is critically important in the regulation and maintenance of T cells and B cells in innate and adaptive immunity. The effects of IL-21 are pleiotropic because of the broad cellular distribution of the IL-21 receptor, and it plays a critical role in T cell-dependent and -independent human B cell differentiation for generating humoral immune responses. This article reviews the current knowledge about the importance of IL-21 and IL-21 receptor interaction in human B cell responses, immune defects of B cells and IL-21 in HIV infection, and the potential applicability of IL-21 in vaccines/immunotherapeutic approaches to augment relevant immune responses.

Vaccination in HIV-infected individuals

Vaccinations are key to limiting the increased risk of severe infectious diseases in HIV-infected patients for whom the risk–benefit ratio has been re-evaluated. Vaccine safety and immunogenicity depend on both vaccine type and immune deficiency, while vaccine-induced immune activation promotes a transient increase in viral load. Vaccine immunogenicity is reduced and wanes more rapidly, strengthening the need for revaccination. While inactivated vaccines are safe, attenuated vaccines are theoretically contraindicated, but the risk of infectious diseases outweighs the risks of severe adverse events in endemic areas, where the majority of HIV-infected individuals live, thus allowing their use when immune deficiency is moderate. Immune reconstitution with HAART has improved vaccine immune response, highlighting the importance of global access to and early initiation of therapy.

Persistent high burden of invasive pneumococcal disease in South African HIV-infected adults in the era of an antiretroviral treatment program

Background

Highly active antiretroviral treatment (HAART) programs have been associated with declines in the burden of invasive pneumococcal disease (IPD) in industrialized countries. The aim of this study was to evaluate trends in IPD hospitalizations in HIV-infected adults in Soweto, South Africa, associated with up-scaling of the HAART program from 2003 to 2008.

Methods

Laboratory-confirmed IPD cases were identified from 2003 through 2008 through an existing surveillance program. The period 2003-04 was designated as the early-HAART era, 2005–06 as the intermediate-HAART era and 2007–08 as the established-HAART era. The incidence of IPD was compared between the early-HAART and established-HAART eras in HIV-infected and–uninfected individuals.

Results

A total of 2,567 IPD cases among individuals older than 18 years were reported from 2003 through 2008. Overall incidence of IPD (per 100,000) did not change during the study period in HIV-infected adults (207.4 cases in the early-HAART and 214.0 cases in the established-HAART era; p = 0.55). IPD incidence, actually increased 1.16-fold (95% CI: 1.01; 1.62) in HIV-infected females between the early-and established-HAART eras (212.1 cases and 246.2 cases, respectively; p = 0.03). The incidence of IPD remained unchanged in HIV-uninfected adults across the three time periods.

Conclusion

Despite a stable prevalence of HIV and the increased roll-out of HAART for treatment of AIDS patients in our setting, the burden of IPD has not decreased among HIV-infected adults. The study indicates a need for ongoing monitoring of disease and HAART program effectiveness to reduce opportunistic infections in African adults with HIV/AIDS, as well as the need to consider alternate strategies including pneumococcal conjugate vaccine immunization for the prevention of IPD in HIV-infected adults.

Bacterial meningitis and Haemophilus influenzae type b conjugate vaccine, Malawi

A retrospective database review showed that Haemophilus influenzae type b conjugate vaccine decreased the annual number of cases of H. influenzae type b meningitis in children in Blantyre, Malawi. Among young bacterial meningitis patients, HIV prevalence was high (36.7% during 1997–2009), and pneumococcus was the most common etiologic agent (57% in 2009).