The need for the mosaic framework
As we progress through the coronavirus disease 2019 (COVID-19) pandemic towards an inter-pandemic period, countries are faced with the need to sustainably transition their surveillance strategies to monitor influenza, SARS-CoV-2, Respiratory Syncytial Virus (RSV) and other respiratory viruses of epidemic and pandemic potential. Population expansion, travel patterns, and global trade also present an ongoing risk of new pandemics, and a continuing need to strengthen early warning surveillance. To face these challenges countries must now increase the number of effective surveillance approaches to address multiple surveillance objectives, and extend partnerships for surveillance and collaborative analyses of data across sectors. Doing so will improve data for decision-making during interpandemic periods and to help ensure that respiratory virus surveillance is both timely and scalable in emergencies.
WHO Member States have requested a coordinated approach to the sustainable monitoring of respiratory viruses of epidemic and pandemic potential (1). For respiratory virus surveillance to function during interpandemic periods, and to be resilient to inform decision-making during times of emergency, surveillance systems must be well-suited to the objectives that they are being implemented to address. Fit-for-purpose surveillance will produce actionable and policy-relevant information that will engender trust and demonstrate their value for money, increasing commitment by public health authorities to invest in surveillance over time. Conversely, poorly targeted, or inefficient surveillance systems may generate sub-optimal or misleading data for decision-making, and not be perceived as cost-effective to sustain or scale in emergencies. Comprehensive surveillance for respiratory viruses involves detecting and assessing emerging or re-emerging pathogens; monitoring epidemiological and clinical characteristics of illness associated with infections and the virological characteristics of respiratory viruses currently in circulation; and informing the use of human health interventions (Figure 1). As it is impossible to address all these objectives with a single surveillance system, multiple systems and complementary investigations (2) must work together to address the many information needs of policy makers. In essence, each system or study serves as a tile in a “mosaic”, and only when viewed together will they provide the complete and understandable picture of the human health risk and impact associated with epidemic and pandemic respiratory viruses in circulation.