Towards the development of a SARS-CoV-2 variant risk assessment tool: expert consultation on the assessment of scientific evidence on emerging variants.

A systematic approach is required for the development of an evidence-based risk assessment tool to robustly estimate the risks and implications of SARS-CoV-2 variants. We conducted a survey among experts involved in technical advisory roles for WHO to capture their assessment of the robustness of different study types that provide evidence for potential changes in transmissibility, antigenicity, virulence, treatability, and detectability of SARS-CoV-2 variants. The views of 62 experts indicated that studies could be grouped on the basis of robustness and reliability for the different risk indicators mentioned. Several study types that experts scored as providing reliable evidence and that can be performed in a timely manner were identified. Although experts from different technical areas had varying responses, there was agreement on the highest and lowest scoring study types. These findings can help to prioritise, harmonise, and optimise study designs for the further development of a systematic, evidence-based, SARS-CoV-2 variant risk assessment tool.

Human norovirus transmission and evolution in a changing world.

Norovirus infections are a major cause of gastroenteritis, and outbreaks occur frequently. Several factors are currently increasing the challenge posed by norovirus infections to global health, notably the increasing number of infections in immunocompromised individuals, who are more susceptible to disease, and the globalization of the food industry, which enables large norovirus outbreaks to occur on an international scale. Furthermore, the rapid rate of the genetic and antigenic evolution of circulating noroviruses complicates the development of vaccines and therapies that are required to counter these challenges. In this Review, we describe recent advances in the study of the transmission, pathogenesis and evolution of human noroviruses, and consider the ongoing risk of norovirus outbreaks, together with the future prospects for therapeutics, in a rapidly changing world.