PP22 -Genomic surveillance and prevalence of RSV in children under three years of age : preliminary data of WHO RSV pilot project phase III

Abstract

Introduction

Respiratory syncytial virus(RSV) causes significant morbidity and mortality in children. WHO has extended global RSV surveillance in children under 2 years of age to elucidate the disease burden. Genetic clades circulating in Sri Lanka have not been reported, which is important for surveillance and vaccine introduction initiatives.

Objectives

To determine the observed prevalence of RSV, circulating subtypes, and genetic diversity and to assess the association between demographic details and clinical symptoms with laboratory results.

Design, setting, and methods

A retrospective study was conducted with selected samples sent between July 2024 and February 2025 from in-ward children under 3 years of age having acute respiratory infections.   The fusion (F) gene, attachment glycoprotein (G) gene, and whole genome of the positive samples were sequenced, and Nextclade software was used to determine the clades. 

Results

Forty samples were tested using the Altona RSV PCR assay 55.6% of whom were from males and 16 (40%) tested positive for RSV, with 07(43.8%) for RSV A and 09(56.2%) for RSV B. Age groups included: birth to 6 months (56%), 7 to 12 months (24%), 13 to 18 months (0%), 19 to 24 months (12.5%), and more than 24 months (6.5%). Two newborns from the ICU and a deceased 3-year-old tested positive for RSV A.

Only three (03) RSV A samples yielded successful sequences, and all of them were Clade A.D.3, and G clade was GA2.3.5. All RSV B samples did not yield productive sequencing data.

Conclusions

Respiratory syncytial virus showed a high prevalence; RSV A and RSV B were equally distributed in this cohort. Only a few samples yielded sequences that did not convey meaningful diversity. Further surveillance with a larger cohort is needed to elucidate disease burden and genetic diversity. This is the first report of RSV clades in Sri Lanka.