[Performance of the case definition of suspected influenza before and during the COVID-19 pandemic].

OBJECTIVE: This study aimed to evaluate the performance, before and during the COVID-19 pandemic, of the case definition of suspected influenza used in community surveillance in Mexico. METHODS: A cross-sectional analysis of a cohort study took place and cases fulfilling the suspected case criteria (n = 20,511), and with laboratory-conclusive evidence (quantitative real-time polymerase chain reaction) to confirm or discard influenza virus infection, were analyzed. RESULTS: A high sensitivity and modest specificity were documented, and this later decreased during the COVID-19 outbreak, as well as its diagnostic accuracy. However, no significant differences were observed in the Area Under the Receiver Operating Characteristics among the analyzed periods. CONCLUSIONS: The evaluated case definition remains to be a cost-effective alternative to identify patients who may benefit from influenza-specific antiviral drugs, even during the COVID-19 global outbreak.