Angela M. Karani, Kenya

KEMRI-Wellcome Trust Research Programme,Kilifi Epidemiology and Demography

Poster Author Of 1 e-Poster

Online Abstracts Vaccines - Impact of Vaccine programs and Serotype Replacement C2 Impact of Vaccine programs and Serotype Replacement

Presenter Of 1 Presentation

ANTIMICROBIAL RESISTANCE PATTERNS IN PNEUMOCOCCAL CARRIAGE PRE AND POST PCV10 INTRODUCTION IN NIGERIA (ID 521)

Abstract

Background

Pneumococcal conjugate vaccines (PCVs) reduce antimicrobial resistance (AMR). In Africa, where disease surveillance is limited, nasopharyngeal carriage studies may reveal PCV impact on AMR . We investigated AMR in pneumococcal carriage in Nigeria.

Methods

Nigeria introduced PCV10 between 2014-2016. Random carriage surveys targeting 1000 participants were conducted pre-(2016) and post-PCV10 (2017-2018) in two locations (rural and urban). PCV10 coverage in 2017 and 2018 was 47% and 55%, respectively. Isolates randomly selected from each survey were tested for antimicrobial resistance using broth micro-dilution.

Results

In 571 pneumococcal isolates, prevalence of resistance was -Tetracycline (69%), Cotrimoxazole (68%), Penicillin (43%) and Chloramphenicol (14%). Serotypes 19F, 6A, 11A, 23F, 3, 16F, 19A, 34 and 6B had a high prevalence of resistance. Prevalence of resistance to any antibiotic differed little by pre- vs post-PCV10 era both overall (86% and 85%) and in rural (73% and 71%) and urban (99% and 98%) samples. No difference was seen in prevalence of resistance among vaccine and non-vaccine serotypes by PCV10 era.

Conclusions

Among healthy Nigerians, prevalence of resistance to commonly used antibiotics is high in carried pneumococci. Although the data do not show any impact of PCV10 on resistance prevalence, the lack of effect may be explained by incomplete coverage levels.

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Author Of 4 Presentations

ANTIMICROBIAL RESISTANCE PATTERNS IN PNEUMOCOCCAL CARRIAGE PRE AND POST PCV10 INTRODUCTION IN NIGERIA (ID 521)

Abstract

Background

Pneumococcal conjugate vaccines (PCVs) reduce antimicrobial resistance (AMR). In Africa, where disease surveillance is limited, nasopharyngeal carriage studies may reveal PCV impact on AMR . We investigated AMR in pneumococcal carriage in Nigeria.

Methods

Nigeria introduced PCV10 between 2014-2016. Random carriage surveys targeting 1000 participants were conducted pre-(2016) and post-PCV10 (2017-2018) in two locations (rural and urban). PCV10 coverage in 2017 and 2018 was 47% and 55%, respectively. Isolates randomly selected from each survey were tested for antimicrobial resistance using broth micro-dilution.

Results

In 571 pneumococcal isolates, prevalence of resistance was -Tetracycline (69%), Cotrimoxazole (68%), Penicillin (43%) and Chloramphenicol (14%). Serotypes 19F, 6A, 11A, 23F, 3, 16F, 19A, 34 and 6B had a high prevalence of resistance. Prevalence of resistance to any antibiotic differed little by pre- vs post-PCV10 era both overall (86% and 85%) and in rural (73% and 71%) and urban (99% and 98%) samples. No difference was seen in prevalence of resistance among vaccine and non-vaccine serotypes by PCV10 era.

Conclusions

Among healthy Nigerians, prevalence of resistance to commonly used antibiotics is high in carried pneumococci. Although the data do not show any impact of PCV10 on resistance prevalence, the lack of effect may be explained by incomplete coverage levels.

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EARLY IMPACT OF INTRODUCING A TEN-VALENT PNEUMOCOCCAL CONJUGATE VACCINE (PCV10) ON PNEUMOCOCCAL CARRIAGE IN NIGERIA (ID 652)

Abstract

Background

As Nigeria transitions from Gavi-support to self-financing of the pneumococcal conjugate vaccine (PCV), decisions on vaccine cost effectiveness should be based on local vaccine impact data. Herd immunity against carriage is a major contributor to PCV impact. So, carriage surveys are a useful option for impact assessments in the absence of disease surveillance systems.

Methods

We conducted nasopharyngeal carriage surveys (2017-2019) according to WHO guidelines among randomly selected residents of two locations (urban and rural) in Nigeria. PCV10 was introduced in 2016 in these locations and reached a modest coverage of 37% and 61% by 2019. Carriage prevalence ratios (PR) before and after PCV10 introduction were estimated using log-binomial regression.

Results

There was a 38% (PR-0.62 [95%CI:0.53-0.72]) and 21% (PR-0.79 [95%CI:0.66-0.94]) reduction in carriage of vaccine serotypes respectively among vaccine-target (<5years) and non-target) (5+ years) groups, mostly due to serotypes 19F, 23F and 6B. Carriage of non-vaccine serotypes increased by 28% (PR-1.28 [95%CI:1.15-1.42]) and 31% (PR-1.31 [95%CI:1.20-1.43]) respectively in these groups; serotypes 6A, 19A, 34, 16F and 11A were prominent.

Conclusions

Within three years of PCV10 introduction, we found early evidence of direct and indirect PCV effects on vaccine serotype carriage as well as serotype replacement in carriage.

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LONG-TERM TRENDS IN NASOPHARYNGEAL CARRIAGE OF VACCINE-TYPE PNEUMOCOCCI: FINDINGS FROM A MATURE 10-VALENT PNEUMOCOCCAL CONJUGATE VACCINE (PCV10) PROGRAM IN KENYA (ID 966)

Abstract

Background

PCV10 was introduced into Kenya’s immunization program in 2011, with catchup in children aged 1-4 years. We evaluated the long-term effect of PCV10 on nasopharyngeal carriage of Streptococcus pneumoniae serotypes included in PCV10.

Methods

Population-based annual cross-sectional nasopharyngeal carriage surveys were conducted in randomly selected individuals between 2009 and 2019 (N= ~1000 in 2019; N= ~500 in all others) in Kilifi, Kenya. Pneumococcal identification was performed per WHO standards. Annual vaccine-type carriage prevalence was modelled using log-binomial regression with a curved function for year and adjustment for age-specific sampling probability.

Results

Compared to 2010, carriage of PCV10-type pneumococci declined significantly through 2019 in children aged <5 years to 6.1% (adjusted prevalence ratio 0.18, 95%CI 0.11-0.30) but not in children aged 5-14 years (prevalence= 7.1%; 0.71, 0.38-1.34) nor adults ≥15 years (prevalence= 1.0%; 0.49, 0.17-1.35). PCV10-type carriage was significantly lower in 2017 compared to 2010 for all age groups and did not differ from carriage prevalence in 2019 (figure).

vt all age categories labelled_20jan2020rev2.png

Conclusions

PCV10-type carriage prevalence appears to be approaching equilibrium, yet residual carriage persists. Virtual elimination of PCV10-type carriage (≤1% in children <5 years; ≤3% in children 5-9 years) – a prerequisite for introduction of reduced dose schedules – is unlikely without implementation of additional strategies.

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GENOMIC ANALYSES OF BACTERIOCINS IN ICELANDIC AND KENYAN PNEUMOCOCCI COLLECTED BEFORE AND AFTER PCV10 INTRODUCTION (ID 503)

Abstract

Background

Widespread use of pneumococcal conjugate vaccines (PCVs) perturb the bacterial population structure, the consequences of which include changes in nasopharyngeal competition among pneumococci. Bacteriocins are antimicrobial peptides produced by bacteria, and are believed to inhibit competing bacterial strains. Twenty putative pneumococcal bacteriocins have been identified: this study aims to compare the bacteriocin distribution among pneumococci recovered pre- and post-PCV10 introduction in two countries.

Methods

Carriage and disease pneumococci collected in Iceland (n=1,916) and Kenya (n=3,257) before and after PCV10 introduction were sequenced and genomes were screened for twenty different bacteriocin sequences. Significant changes in the prevalence of genetic lineages, serotypes, and bacteriocins post-PCV10 introduction were assessed.

Results

PCV10 use led to a significant reduction in the prevalence of vaccine serotypes and associated genetic lineages in both countries. Overall, 18 of 20 bacteriocins were detected in 1% to 100% of genomes. The prevalence of six bacteriocins was significantly altered in the Kenyan dataset post-PCV10, and three of these also changed in the Icelandic dataset. These bacteriocins were associated with genetic lineages that also significantly changed in prevalence.

Conclusions

The bacteriocin distribution changed significantly following PCV10 introduction in Iceland and Kenya. The biological relevance of these changes to competition dynamics is currently under investigation.

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