Impact of COVID-19 Nonpharmaceutical Interventions on the Extent of Norovirus Contamination in Oyster Production Areas in Ireland during Winter 2020 to 2021

Abstract

A significant decrease in norovirus prevalence and concentration was observed in oyster production areas in Ireland during winter 2020/21. Oyster production areas impacted by human wastewater discharges that were under-going norovirus surveillance since 2018 were investigated. Samples collected in the winter seasons of 2018/19 and 2019/20, prior to when the COVID-19 pandemic interventions were applied, showed a prevalence of 94.3% and 96.6% respectively and geometric mean concentrations of 533 and 323 genome copies per gram (gcg -1 ) respectively. These values decreased significantly during the winter of 2020/21 (prevalence of 63.2% and geometric concentration of <LOQ) coinciding with the control measures to mitigate the transmission of SARS-CoV-2. Divergence between norovirus GI and GII prevalence and concentrations was observed over the three year monitoring period. Norovirus GII was the dominant genogroup detected in winter 2020/21 with over half of samples positive although concentrations detected were significantly lower than pre-pandemic winters with a geometric mean concentration of <LOQ.

Piloting wastewater-based surveillance of norovirus in England

“…However, during the COVID-19 pandemic, there was evidence of decreased NoV prevalence due to the introduction of COVID-19-related nonpharmaceutical interventions (NPIs) in many countries. For example, a study from oyster production areas in Ireland showed that while NoV was detected in 94.3 and 96.6% of oyster samples in the two winters preceding the COVID-19 pandemic, this value decreased to 63.2% in the winter of 2020 to 2021 (Keaveney et al, 2022). Wang et al (2023), showed that the transmission of NoV GII was significantly reduced by the introduction of public restrictions on movement and good hygiene practice in Sweden.…”

Circulating trends of hand, foot, and mouth disease in Hubei Province, China: Impact from the COVID-19 pandemic

“…The most restrictive strategy of NPIs was implemented through the all of 2020 and lasted until 2022. NPIs implemented worldwide during the COVID-19 pandemic not only efficiently contained COVID-19 but also reduced the incidence of other respiratory and gastrointestinal infectious diseases [ [1] , [2] , [3] ].…”