Pneumococcal nasopharyngeal carriage among infants born to human immunodeficiency virus-infected mothers immunized with pneumococcal polysaccharide vaccine during gestation

Effect of Maternal Vaccination of PCV-10, PPV-23 or Placebo on the Immunogenicity of PCV-10 in HIV-exposed Uninfected Infants: A Randomized Clinical Trial

BACKGROUND

The effect of pneumococcal vaccination of mothers with HIV on infant responses to childhood vaccination has not been studied. We compared the immunogenicity of PCV-10 in HIV-exposed uninfected infants born to mothers who received PCV-10, PPV-23 or placebo during pregnancy.

METHODS

Antibody levels against seven serotypes were measured at birth, before the 1 st and 2 nd doses of PCV-10 and after the completion of the 2-dose regimen in 347 infants, including 112 born to mothers who received PPV-23, 112 PCV-10, and 119 placebo during pregnancy. Seroprotection was defined by antibody levels ≥0.35µg/ml.

RESULTS

At birth and 8 weeks of life, antibody levels were similar in infants born to PCV-10- or PPV-23-recipient mothers and higher than infants of placebo-recipient mothers. After the last dose of PCV-10, infants in the maternal PCV-10 group had significantly lower antibody levels against five serotypes compared to infants in the maternal PPV-23 group; against three serotypes compared to infants in the maternal placebo group; and did not have higher antibody levels against any serotype. The seroprotection rate against seven serotypes was 50% in infants in the maternal PCV-10 compared to 71% in each of the maternal PPV-23 and placebo groups (p<0.0001).

CONCLUSIONS

Administration of PCV-10 during pregnancy was associated with decreased antibody responses to PCV-10 and seroprotection rates in infants. Considering that PCV-10 and PPV-23 had similar immunogenicity in pregnant women with HIV and that administration of PPV-23 did not affect the immunogenicity of PCV-10 in infants, PPV-23 in pregnancy may be preferred over PCV-10.

Maternal immunisation to improve the health of HIV-exposed infants

HIV-exposed but uninfected (HEU) infants are at an increased risk of many infectious diseases that can contribute to the high mortality seen among HEU children. Maternal immunisation could be a promising strategy to reduce infections in HEU infants. However, very little research has explored the effect of HIV on the immunogenicity and effectiveness of vaccines given during pregnancy. We review the available evidence on maternal immunisation among women living with HIV (WLWH) for all vaccines recommended, considered, or being investigated for routine or risk-based use during pregnancy. Of the 11 vaccines included, only three have been investigated in WLWH. Available evidence suggests that maternal HIV infection limits the immunogenicity of several vaccines, leaving HEU infants more susceptible to infection during their first few months of life. Whether maternal immunisation reduces the infectious morbidity and mortality associated with infectious diseases in HEU children remains unknown. We conclude the Review by identifying future research priorities.

Effectiveness and practical uses of 23-valent pneumococcal polysaccharide vaccine in healthy and special populations

Streptococcus pneumonia (S. pneumoniae) is responsible for significant morbidity and mortality throughout the world. The 23-valent pneumococcal polysaccharide vaccines (PPV23) have been widely used for many years, but challenges are remaining in some respects, especially for its effectiveness among high-risk populations and older adults. This review aims to summarize recent clinical trials and studies of PPV23 vaccination among healthy people ≥ 2 years of age and those with high-risk conditions such as pregnant women, individuals with immunocompromising diseases and other chronic conditions, and provide health officials in China and other developing countries a comprehensive understanding of the current vaccination strategies for PPV23 and for the combined use of PPV23 and pneumococcal conjugate vaccines (PCVs) in adults.

Maternal Immunization with Pneumococcal Polysaccharide Vaccine: Persistence of Maternal Antibodies in Infants

OBJECTIVE

To evaluate the level and the persistence of maternal antibodies in infants after maternal immunization with pneumococcal polysaccharide vaccine (Pn23V).

METHODS

Pregnant women were assigned to two groups, during routine low-risk pre-natal visits. The first Group (VAC) received the Pn23V vaccine shortly after enrolment at 28 weeks or later, and the second Group (NO_VAC) received no vaccine. To investigate the antibody persistence, we collected blood samples from the mothers after 1 month of delivery and from the infants at 1 and 6 months of age.

RESULTS

Antibody titers were measured for serotypes 1, 6B and 14. Geometric mean antibody concentrations of specific immunoglobulin G were significantly higher in the vaccinated group compared with unvaccinated controls for all three serotypes tested.

CONCLUSION

Despite the antibody level's decline, at 6 months of age, proportions  >0.35 μg/ml remained higher in the infants of vaccinated mothers than controls for all three serotypes.

Maternal HIV and Paediatric Lung Health

With improved prevention of mother to child transmission of HIV, paediatric HIV disease is less common. However, the number of HIV exposed but uninfected infants is growing. Exposure to maternal HIV impacts infant respiratory health through an increase in known risk factors such as increased preterm birth and low birth weight, suboptimal breastfeeding, increased psychosocial stressors and increased exposure to infective pathogens. Exposure to the HIV virus and altered maternal immune environment result in immunologic changes in the infant that may contribute to respiratory disease risk. HIV exposed infants are at increased risk for severe pneumonia with poorer outcomes compared to unexposed infants. Maternal ART and optimal nutrition, including breastfeeding in high infective disease burden settings, reduce morbidity and mortality in HIV exposed infants and should be prioritized. The impact of exposure to maternal HIV on normal lung growth and risk for chronic respiratory disease is unknown and warrants further investigation.

Nasopharyngeal carriage of Streptococcus pneumoniae in adults infected with human immunodeficiency virus in Jakarta, Indonesia

This study investigated the distribution of serotype and antimicrobial susceptibility of Streptococcus pneumoniae carried by adults infected with human immunodeficiency virus (HIV) in Jakarta, Indonesia. Specimens of nasopharyngeal swab were collected from 200 HIV infected adults aged 21 to 63 years. Identification of S. pneumoniae was done by optochin susceptibility test and PCR for the presence of psaA and lytA genes. Serotyping was performed with sequential multiplex PCR and antibiotic susceptibility with the disk diffusion method. S. pneumoniae strains were carried by 10% adults with serotype 6A/B 20% was common serotype among cultured strains in 20 adults. Most of isolates were susceptible to chloramphenicol (80%) followed by clindamycin (75%), erythromycin (75%), penicillin (55%), and tetracycline (50%). This study found resistance to sulphamethoxazole/trimethoprim was most common with only 15% of strains being susceptible. High non-susceptibility to sulphamethoxazole/trimethoprim was observed in S. pneumoniae strains carried by HIV infected adults in Jakarta, Indonesia.

Humoral immune responses to Streptococcus pneumoniae in the setting of HIV-1 infection

Streptococcus pneumoniae (pneumococcus) remains one of the most commonly identified causes of bacterial infection in the general population, and the risk is 30-100 fold higher in HIV-infected individuals. Both innate and adaptive host immune responses to pneumococcal infection are important against pathogen invasion. Pneumococcal-specific IgA antibody (Ab) is key to control infection at the mucosal sites. Ab responses against pneumococcal infection by B cells can be generated through T cell-dependent or T cell-independent pathways. Depletion of CD4+ T cells is a hallmark of immunodeficiency in HIV infection and this defect also contributes to B cell dysfunction, which predisposes to infections such as the pneumococcus. Two pneumococcal vaccines have been demonstrated to have potential benefits for HIV-infected patients. One is a T cell dependent 13-valent pneumococcal conjugate vaccine (PCV13); the other is a T cell independent 23-valent pneumococcal polysaccharide vaccine (PPV23). However, many questions remain unknown regarding these two vaccines in the clinical setting in HIV disease. Here we review the latest research regarding B cell immune responses against pneumococcal antigens, whether derived from potentially invading pathogens or vaccinations, in the setting of HIV-1 infection.

Acquisition of Streptococcus pneumoniae in pneumococcal conjugate vaccine-naïve South African children and their mothers

BACKGROUND

Pneumococcal nasopharyngeal colonization is a prerequisite to developing pneumococcal disease. We investigated the dynamics of pneumococcal colonization in perinatal HIV-unexposed and HIV-exposed children and their mothers and risk factors associated with new serotypes acquisition.

METHODS

Two hundred forty-three mother-child pairs (120 HIV-infected, 123 HIV-uninfected mothers) were studied at 4.4, 7.2, 9.4, 12.3 and 16.0 months of the child's age. Demographic data, nasopharyngeal swabs, as well as oropharyngeal swabs, from mothers were collected for pneumococcal conventional culture and serotyping by the Quellung method.

RESULTS

The rate of new serotype acquisition during the 16 months did not differ between HIV-exposed (49.1%) and HIV-unexposed (52.0%) children, or between HIV-infected (18.9%) and HIV-uninfected (19.5%) mothers. Serotypes included in the 7-valent pneumococcal conjugate vaccine (PCV7) were acquired more often by HIV-infected (10.0%) compared with HIV-uninfected mothers (6.4%; P = 0.03). On multivariate analysis, day-care attendance (adjusted odds ratio [AOR], = 1.80, P = 0.02) and maternal pneumococcal colonization (AOR = 1.54, P = 0.01) were positively associated with pneumococcal acquisition in the child, whereas breast-feeding had a protective effect on PCV7-serotype acquisition in HIV-uninfected children. New acquisition of PCV7 and PCV13 serotypes in the mother was positively associated with colonization in the child (AOR = 2.01, P = 0.006 and AOR = 2.04, P = 0.002, respectively).

CONCLUSIONS

There is an association of acquisition of PCV7 and PCV13 serotypes between young children and their mothers. The higher prevalence of PCV7 serotype in HIV-infected mothers suggests that they may be a reservoir for transmission of these serotypes, which could delay indirect effects of PCV in settings with a high HIV burden.

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.

Pathogen diversity and hidden regimes of apparent competition

Competition through cross-reacting host immune responses, a form of apparent competition, is a major driver of pathogen evolution and diversity. Most models of pathogens have focused on intraspecific interactions to explain observed patterns. Two recent experiments suggested that Haemophilus influenzae, a common nasopharyngeal colonizer of humans, might alter the immune environment in a way that favors otherwise less fit serotypes of another common pathogen, pneumococcus. Using a computational model, we demonstrate that H. influenzae, if it consistently raises the fitness of the less fit serotypes, can strongly promote pneumococcal diversity. However, the effects of H. influenzae are so sensitive to the prevalence of H. influenzae that this species is unlikely to be the main driver of serotype coexistence. Interactions that significantly affect diversity could furthermore be extremely difficult to detect through co-occurrence analysis alone. These results suggest that small differences in strains' adaptations to different immunological regimes, which are shaped by coinfections with other pathogens, can have dramatic effects on strain dynamics and patterns of phenotypic variation. Studies of microbial communities might therefore benefit from the use of varied approaches to infer the presence of indirect interactions.

Pneumococcal nasopharyngeal carriage in infants of mothers immunized with 23V non-conjugate pneumococcal polysaccharide vaccine

To assess the effects of maternal immunization on pneumococcal colonization in infants, pregnant women were assigned into three groups. The group Pregn Vac received the Pn23V during pregnancy, the group Puerp Vac received vaccine during immediate puerperium and the group No Vac received no vaccine. Nasopharyngeal samples were collected at 3 and 6 months. A total of 150 pregnant women were selected during the prenatal period. The proportion of pneumococcal carriage in at least one evaluation was in group Pregn Vac 22.2% (10/45), group Puerp Vac 23.4% (11/47) and group No Vac 21.2% (10/47), respectively. The most frequently isolated serotype in group Puerp Va and group No Vac was 6B and 6A. In the Pregn Vac, the most important serotype was 19F. Although this study was unable to demonstrate any effect of maternal vaccination in reducing pneumococcal colonization, reduction of colonization for serotype 6B in infants may be an important effect.

Can infants be protected by means of maternal vaccination?

The administration of vaccines is not usually recommended in pregnant women because of a fear of severe adverse events for the fetus. However, contraindication to vaccination applies only to vaccines based on live attenuated viruses for the theoretical possibility that they might infect the fetus. In contrast, the use of several inactivated vaccines is useful and recommended. As a result of the transplacental passage of antibodies, maternal immunization can reduce the risk of vaccine-preventable diseases that may occur in the first months of life before the start or completion of the suggested vaccination schedule. One of the best examples is vaccination against influenza that can protect pregnant women from a disease that can lead to hospitalization and death in a significantly higher number of cases than in the general population and can induce protective specific antibody levels as well as being effective in infants in the first months of life. Other examples are vaccinations against tetanus, pertussis, pneumococcal infections and Haemophilus influenzae type b infection. This review analyses the advantages and limitations of maternal immunization as revealed by experience and the main publications.

Safety of hepatitis B, pneumococcal polysaccharide and meningococcal polysaccharide vaccines in pregnancy: a systematic review

Immunization during pregnancy has the potential to protect the mother and the newborn from preventable diseases. Current recommendations suggest that inactivated vaccines might be considered during pregnancy when the benefits outweigh the risks. In this review, we aimed to evaluate the safety of hepatitis B (HB) vaccine, pneumococcal polysaccharide vaccine (PPSV) and meningococcal polysaccharide vaccine (MPSV) administration during pregnancy by systematically reviewing the available evidence in PubMed and Scopus databases, as well as postmarketing surveillance data (including the Vaccine Adverse Event Reporting System [VAERS] database). A total of 18 studies were eligible for inclusion in the review. Six studies provided data on HB vaccine, six on PPSV and three on MPSV; three additional studies compared PPSV with MPSV. Additionally, 91 reports on vaccinations of pregnant women were identified from postmarketing surveillance data (88 on HB vaccine, 2 on PPSV, 1 on MPSV). The most common complaints were local reactions, including tenderness and swelling. Overall, immunization during pregnancy did not seem to be associated with a teratogenic effect on the fetus, preterm labour or spontaneous abortion. However, the lack of randomized, placebo-controlled trials, or even large cohort studies, in addition to the inherent limitations of the reviewed observational studies with small statistical power, precluded safe conclusions. Large, prospective, population-based cohort studies are needed to elucidate this issue.