Stephen Hughes, United Kingdom

Manchester University NHS Foundation Trust Department of Paediatric Allergy and Immunology- Royal Manchester Childrens Hospital

Author Of 2 Presentations

MICROARRAY RESULTS FROM NASOPHARYNGEAL LYTA-POSITIVE CHILDREN AND ADULTS: OBSERVATIONAL DATA FROM THE TRANSMISSION OF PNEUMOCOCCUS STUDY (ID 728)

Abstract

Background

Quantification of Streptococcus pneumoniae (Sp) carriage density and identification of serotypes in contacts contribute to understanding Sp transmission and thus evaluating pneumococcal conjugate vaccine impact.

Methods

266 lytA-positive nasopharyngeal samples (NPS) taken during season 1 (of 2, October-December 2017) of the Transmission of Pneumococcus (TOP) study (see abstract 715) were analysed by microarray. NPS were collected from 120 families, 2-weekly over 2 months.

Results

83/120 index children (2-year-olds) were lytA positive at baseline (visit 1): the three most common serotypes were 11A, 15B and 35F (n=83) (Graph 1).

In 17/28 families (28 index children, 45 contacts: 26 <16-year-olds and 19), index children shared ≥1 strain/serotype with ≥1 household contact.

40% (107/266) of lytA-positive NPS analysed had multiple serotypes/strains.

Sp was not detected in some lytA-positive samples but rather related streptococcal species, particularly from participants aged ≥5 years (Table 1).

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Conclusions

NP carriage of the same Sp serotypes by multiple household members suggests that household Sp transmission occurs.

Multiple serotype carriage was observed in a significant proportion of participants.

Among young children, the age group most likely to transmit Sp, lytA was more predictive of true Sp infection than it was among older persons.

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PNEUMOCOCCAL CARRIAGE: RATES AND DENSITY IN 2-YEAR-OLD CHILDREN AND THEIR FAMILIES: THE TRANSMISSION OF PNEUMOCOCCUS STUDY, EARLY RESULTS (ID 715)

Abstract

Background

Interruption of vaccine serotype transmission underlies effectiveness of pneumococcal conjugate vaccine (PCV) programmes at population level. Streptococcus pneumoniae (Sp) nasal carriage density is affected by upper respiratory tract viral infections and PCV. The impact of carriage density on transmission is unknown.

In a multi-centre prospective randomised stepped-wedge trial, we have used the Live Attenuated Influenza Vaccine (LAIV) to modulate Sp carriage density in 2-year-olds and assess impact on household transmission.

Methods

410 families were recruited across 10 UK sites. Families were randomised 1:1 to early or late (4 weeks later) index-child LAIV; saliva and nasopharyngeal samples (NPS) were collected 2-weekly over 2 months. Samples are being analysed for Sp by real-time quantitative PCR (lytA), culture amplification and microarray.

Results

SP nasal carriage rate, densities and density range are highest in our index children (Table 1 for baseline (visit 1) and Figure 1 for visits 1-5).

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Conclusions

The range of Sp carriage density is very wide with rates and densities in keeping with the literature. The impact of density on Sp transmission will be analysed when full results are available, June 2020.

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