Impact on laboratory medicine of transitioning from COVID-19 pandemic to “tripledemic”

It has now become clear that SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) will remain among us for long time, becoming a “harmingly” endemic infectious disease. Although virulence and pathogenicity have gradually decreased over time, the infectivity has instead increased after the emergence of new sublineages belonging to Omicron family, so that the volume of tests that need to be performed for diagnosing and monitoring coronavirus disease 2019 (COVID-19) remains paramount. The situation has become even more complicated after resurgence of other infectious respiratory diseases, namely Influenza and Respiratory Syncytial Virus (RSV), which are now responsible for an unprecedented “tripledemic”. In this catastrophic scenario, laboratory medicine needs to be proactive and timely adapt to the new challenge. Further development and implementation of SARS-CoV-2 antigen rapid diagnostic testing (Ag-RDT) will play a crucial role in the future, especially encompassing devices that will enable to confirm (or rule out) more infectious diseases at the same time (i.e., COVID-19, Influenza and RSV). Considering that the clinical phenotypes of the three viruses is overlapping, new diagnostic tests designed for simultaneous assessment of multiple viruses within a single Ag-RDT device represent a valuable option for achieving a rapid differential diagnosis between different respiratory infections, or even for diagnosing multiple concomitant infections. A novel strategy could hence be profiled, entailing the screening by means of combined Ag-RDT of all subjects whose infective status may jeopardize their own health as well as the health of other people.