Molecular epidemiology and evolution of norovirus in Australia and New Zealand, 2018 to 2020

This is the authors' abstract. We don't add key points for this paper.

BACKGROUND: Norovirus causes an estimated 699 million cases of gastroenteritis and 219,000 deaths each year. Historically, novel strains with a genogroup II genotype 4 (GII.4) capsid have emerged every 3-5 years to cause gastroenteritis pandemics. Contrary to historical trends, viruses with aGII.4 Sydney 2012 capsid have extended the timeframe of capsid circulation, well beyond the usual 3-5 years, through genetic recombination to obtain new non-structural regions, for example, a GII.P16 ORF1. OBJECTIVES AND METHODS: The molecular evolution in the GII.4 capsid of strains in New South Wales (NSW), Australia and New Zealand (NZ) before and into the COVID-19 pandemic (2018-20) was investigated by sequencing noroviruses from clinical specimens and wastewater. RESULTS: gc/L). The relaxation of lockdown measures in late-2020 coincided with a strong resurgence of GII.2[P16] prevalence both clinically and in wastewater in NSW and Melbourne, accompanied by a decline in the diversity of circulating noroviruses. Conclusion: In summary, COVID-19 disrupted the strain diversity and levels of norovirus in Australia and New Zealand.