Characterization of circulating influenza viruses in Andalusia during the 2018-2019 season.

Introduction:

Due to the high genetic and antigenic variability, influenza viruses cause annual epidemics and sporadic pandemics. Morbidity and mortality are also high. Annual vaccination is recommended to prevent infection in risk groups and also,

effective antivirals are available for treatment of patients with severe disease, Influenza is subjected to world surveillance, through networks comprised by epidemiologists,

sentinel physicians and laboratories, being the later responsible for the identification, isolation and characterisation of seasonal viruses, to know their similarity to vaccine strains, mutations associated with antiviral resistance and, if necessary, to early detect possible pandemic viruses.

Objetives:

To identify and characterise influenza viruses detected in Andalucía during the 2018-2019 season.

Material and methods:

Genetic characterisation by Sanger sequencing of selected

influenza virus strains isolated in cell culture in the Reference Laboratory for Influenza at Hospital Universitario Virgen de las Nieves. Samples proceeded from the Andalusian Sentinel and Severe Cases Surveillance Networks.

Results:

From the 73 strains analysed, 51 were H1pdm09 (30

A/Switzerland/3330/2017, 14 A/Michigan/45/2015, 6 A/Switzerland/2656/2017 and 1A/Paris/1447/2017), and 22 H3 (16 A/Alsace/1746/2018 and 6 A/England/538/2018).

None out of 21 strains have shown mutations associated to oseltamivir resistance.

Conclusions:

Circulating H3 viruses haven’t been antigenically similar to the H3 vaccine strain. All studied H1pdm09 were susceptible to oseltamivir.