The influenza-associated excess respiratory deaths for all ages and individuals aged 60 years or older were estimated by subtracting the predicted number of respiratory deaths assuming that the influenza virus activity proxy was 0 (E[Y|X=0]) from the predicted number of respiratory deaths using the observed influenza virus activity proxy (E[Y|X=x_obs]).5 Y indicates the predicted respiratory death rate; X represents influenza virus activity proxy; and x_obs refers to the observed influenza virus activity proxy.