Epidemiology and Genetic Variability of Circulating Influenza B Viruses in Uruguay, 2012-2019.

María José Rivas,Viviana Ramas,Héctor Chiparelli,Miguel Alegretti,Natalia Goñi,Leticia Cóppola

doi:10.3390/microorganisms8040591

María José Rivas, Viviana Ramas + Show 4 more

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https://doi.org/10.3390/microorganisms8040591

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Journal: Microorganisms	Publication Date: Apr 19, 2020
Citations: 6	License type: CC BY 4.0

Affiliation: Ministerio de Salud Pública

Abstract

Influenza B viruses (IBV) are an important cause of morbidity and mortality during interpandemic periods in the human population. Two phylogenetically distinct IBV lineages, B/Yamagata and B/Victoria, co-circulate worldwide and they present challenges for vaccine strain selection. Until the present study, there was little information regarding the pattern of the circulating strains of IBV in Uruguay. A subset of positive influenza B samples from influenza-like illness (ILI) outpatients and severe acute respiratory illness (SARI) inpatients detected in sentinel hospitals in Uruguay during 2012–2019 were selected. The sequencing of the hemagglutinin (HA) and neuraminidase (NA) genes showed substitutions at the amino acid level. Phylogenetic analysis reveals the co-circulation of both lineages in almost all seasonal epidemics in Uruguay, and allows recognizing a lineage-level vaccine mismatch in approximately one-third of the seasons studied. The epidemiological results show that the proportion of IBV found in ILI was significantly higher than the observed in SARI cases across different groups of age (9.7% ILI, 3.2% SARI) and patients between 5–14 years constituted the majority (33%) of all influenza B infection (p < 0.05). Interestingly, we found that individuals >25 years were particularly vulnerable to Yamagata lineage infections.

Highlights

Influenza viruses are considered to be a major human health problem with a global distribution, with considerable impact on the quality of life and productivity of the society
Age distributions show that children aged 0–4 years old were the largest group of influenza-like illness (ILI) (166/455, 36%) and severe acute respiratory illness (SARI) (3044/5299, 57%) patients (Table 1)
Our findings revealed that types A and B influenza viruses almost always co-circulated throughout 2012–2019 and they confirm the important role of influenza B virus in the spread of infection in the population

Summary

Introduction

Influenza viruses are considered to be a major human health problem with a global distribution, with considerable impact on the quality of life and productivity of the society. Influenza A viruses (IAV) are responsible for pandemics and they have major rates of hospitalization and mortality attribution, influenza B viruses (IBV) cause epidemics worldwide annually, becoming responsible in some years for more than 25% of human seasonal influenza infections, and its prevention represents an important public health priority [3,4,5]. Recent reports have highlighted the potential differences in the epidemiology of Victoria and Yamagata lineage viruses, including younger average ages of persons with Victoria virus infection and greater transmissibility. Despite being only two lineages, the selection of the right influenza B virus strain in the vaccine has been proven very difficult, because the dominant lineage changes over time, as result, the vaccine efficacy decreased when the included vaccine strain did not match the circulating epidemic strain [13]

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