Fig. 1

Gender dynamics. Gender was measured in the 2020-21 (A), 2021-22 (B), and 2022–2023 (C) influenza seasons using a modified version of the short-form Bem Sex Role Inventory. Based on responses to questions about six instrumental/masculine (I/M) traits (leadership abilities, strong personality, acts as leader, dominant, makes decisions easily, defends own beliefs) and six expressive/feminine (E/F) traits (warm, gentle, affectionate, sympathetic, sensitive to other’s needs, tender), mean femininity and masculinity scores were calculated and compared to the population median to assign participants into one of four gender categories. Dashed lines represent the median femininity and masculinity scores for each year (A-C). The distribution of the four gender categories by age group is shown in D