This publication by the World Health Organization (WHO) addresses the adaptation of influenza sentinel surveillance systems to include COVID-19 virological surveillance. It provides interim guidance on maintaining influenza surveillance while monitoring SARS-CoV-2, reflecting lessons learned during the COVID-19 pandemic. The document emphasizes the importance of sentinel surveillance in providing timely information on viral trends and the co-circulation of influenza and COVID-19. The guidance aims to support national, regional, and global responses to these infectious diseases, enhancing preparedness and response strategies. It targets public health officials, epidemiologists, and policymakers involved in disease surveillance.