Epidemiology and Genotypes Circulating of Respiratory Syncytial Virus in Cote d’Ivoire, 2022-2023

The burden of human respiratory syncytial virus (RSV) continues to grow worldwide, particularly among the youngest segment of the population. This study aimed to describe the epidemiological and clinical characteristics of RSV circulating in Côte d'Ivoire between 2022 and 2023, and to characterize the genotypes in circulation. A total of 8,317 patients presenting with severe acute respiratory infections (SARI) or influenza-like illness (ILI) were enrolled in the study. Respiratory specimens were tested for RSV using real-time PCR. Whole-genome sequencing and phylogenetic analyses were conducted to identify circulating genotypes. Among the enrolled patients, 3,208 (38.6%) had SARI and 5,109 (61.4%) had ILI. The overall RSV positivity rate was 5.6%. The proportion of females testing positive was significantly higher than that of males (5.8% vs. 5.4%, p = 0.007). The median age of RSV-positive individuals was 1 year (interquartile range [IQR]: 0–2 years). No significant difference in RSV positivity was observed between SARI and ILI cases (p = 0.870). In terms of seasonality, RSV positivity peaked in August, reaching 12%. Among RSV-positive cases, 81.4% were RSV group B and 18.6% were RSV group A. Phylogenetic analysis revealed that most RSV-A strains belonged to clade A.D.5.1, while RSV-B strains were predominantly of clade B.D.E.1. RSV circulation in Côte d'Ivoire exhibited a clear seasonal pattern, with peak activity during the rainy season. The most affected population was children under two years of age. Molecular analysis indicated that clade B.D.E.1 has replaced B.D.4.1.1 as the dominant RSV-B lineage. Continued genomic surveillance is essential to monitor RSV evolution and inform future prevention strategies, including vaccine development and immunization policies.