Annual report on influenza viruses received and tested by the Melbourne WHO Collaborating Centre for Reference and Research on Influenza in 2016.

As part of its role in the World Health Organization’s (WHO) Global Influenza Surveillance and Response System (GISRS), the WHO Collaborating Centre for Reference and Research on Influenza in Melbourne received a total of 4,247 human influenza positive samples during 2016. Viruses were analysed for their antigenic, genetic and antiviral susceptibility properties and also propagated in qualified cells and hens eggs for potential seasonal influenza vaccine virus candidates. In 2016, influenza A(H3) viruses predominated over influenza A(H1)pdm09 and B viruses, accounting for a total of 51% of all viruses analysed. The vast majority of A(H1)pdm09, A(H3) and influenza B viruses analysed at the Centre were found to be antigenically similar to the respective WHO recommended vaccine strains for the Southern Hemisphere in 2016. However, phylogenetic analysis of a selection of viruses indicated that the majority of circulating A(H3) viruses had undergone some genetic drift relative to the WHO recommended strain for 2016. Of more than 3,000 samples tested for resistance to the neuraminidase inhibitors oseltamivir and zanamivir, six A(H1)pdm09 viruses and two B/Victoria lineage viruses showed highly reduced inhibition to oseltamivir.