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

A systematic review of pneumococcal conjugate vaccine impact on pneumococcal nasopharyngeal colonisation density in children under 5 years of age

BACKGROUND

High pneumococcal carriage density has been associated with severe pneumonia in some settings. The impact of pneumococcal conjugate vaccines (PCVs) on pneumococcal carriage density has been variable. The aim of this systematic literature review is to describe the effect of PCV7, PCV10 and PCV13 on pneumococcal colonisation density in children under five years old.

METHODS

We included peer reviewed English literature published between 2000 and 2021 to identify relevant articles using Embase, Medline and PubMed. Original research articles of any study design in countries where PCV has been introduced/studied were included. Quality (risk) assessment was performed using tools developed by the National Heart Brain and Lung Institute for inclusion in this review. We used a narrative synthesis to present results.

RESULTS

Ten studies were included from 1941 articles reviewed. There were two randomised controlled trials, two cluster randomised trials, one case control study, one retrospective cohort study and four cross sectional studies. Three studies used semiquantitative culture methods to determine density while the remaining studies used quantitative molecular techniques. Three studies reported an increase in density and three studies found a decrease in density among vaccinated compared with unvaccinated children. Four studies found no effect. There was considerable heterogeneity in the study populations, study design and laboratory methods.

CONCLUSION

There was no consensus regarding the impact of PCV on pneumococcal nasopharyngeal density. We recommend the use of standardised methods to evaluate PCV impact on density.

Determinants of vaccine uptake in HIV-affected families from West Bengal

Children living with Human Immunodeficiency virus (HIV; CLH) have special vaccine needs. Determinants of household-level uptake of vaccines need to be examined in high-risk families with CLH. We previously conducted a study on the impact of Haemophilus influenzae type b conjugate vaccine and pneumococcal conjugate vaccine (PCV-13) in 125 HIV-affected families and 47 HIV-unaffected families in West Bengal. We then interviewed 99 of these 172 families who had participated in the study to understand the household-level factors that determine vaccine uptake. Sixty-four of the 99 families had one or more CLH. Within these 64 families, 30% of CLH had missed vaccines under the universal immunization program (UIP), compared to only 6% of HIV-uninfected children (HUC) (p = .001). Maternal HIV positivity in a family increased risk of missing UIP vaccines nearly five times (4.82, p = .001). Almost all families accessed UIP vaccines at local primary vaccination centers, but 14% of families experienced stigma due to HIV and avoided getting one or more vaccine doses. In contrast, in our study, 100% of HIV-affected families actively sought PCV-13 and HibCV, despite having to travel. Factors that influenced uptake included awareness generation and activation by an outreach worker and availability of vaccines on pick-up days for anti-retroviral therapy. Eighty-six percent of families strongly recommended PCV-13 to other families. To conclude, while we found that CLH have barriers to getting vaccinations, a program designed to take into consideration the obstacles that HIV-affected families face showed a high rate of vaccine uptake.

Nasopharyngeal carriage and antimicrobial susceptibility profile of Haemophilus influenzae among patients infected with HIV in Jakarta, Indonesia

In this study, the prevalence of nasopharyngeal carriage and the antimicrobial susceptibility profile of Haemophilus influenzae were investigated in children and adults with HIV infection in Jakarta, Indonesia. Thirty-four H. influenzae isolates were identified in the children (n=16/90; 18%) and adults (n=18/200; 9%) infected with HIV. All isolates were nontypeable H. influenzae and were less susceptible to ampicillin (62%) and trimethoprim/sulfamethoxazole (41%). In this study, the H. influenzae strains carried by patients infected with HIV were dominated by non-capsulated types.

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.

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.

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.

Barriers to HIV remission research in low- and middle-income countries

INTRODUCTION

HIV eradication and remission research has largely taken place in high-income countries. In low- and middle-income countries (LMIC), there may be factors that have a substantial impact on the size of the latent HIV reservoir and the immunological response to infection. If a curative strategy is to be available to all HIV-infected individuals, these factors must be understood.

METHODS

We use a scoping review to examine the literature on biological factors that may have an impact on HIV persistence in LMIC. Three databases were searched without date restrictions.

RESULTS

Uncontrolled viral replication and higher coinfection prevalence may alter the immunological milieu of individuals in LMIC and increase the size of the HIV reservoir. Differences in HIV subtype could also influence the measurement and size of the HIV reservoir. Immune activation may differ due to late presentation to care, presence of chronic infections, increased gut translocation of bacterial products and poor nutrition.

CONCLUSIONS

Research on HIV remission is urgently needed in LMIC. Research into chronic immune activation in resource poor environments, the immune response to infection, the mechanisms of HIV persistence and latency in different viral clades and the effect of the microbiological milieu must be performed. Geographic differences, which may be substantial and may delay access to curative strategies, should be identified.