On February 13, 2017, the Food and Drug Administration (FDA) reclassified rapid influenza virus antigen detection test systems (RIDTs) that were regulated as influenza virus serological reagents from class I into class II with special controls. For antigen based RIDTs that were legally marketed prior to February 13, 2017, FDA delayed enforcing these special controls in order to give manufacturers time to ensure their devices meet minimum performance criteria and to submit 510(k) applications for significantly changed or modified devices. The new special controls for previously marketed RIDTs will now go into effect on January 12, 2018. The special controls require that RIDTs meet minimum sensitivity and specificity criteria; that manufacturers compare device performance with FDA-accepted methods; and that RIDTs undergo analytical reactivity testing with contemporary influenza strains as well as flu strains for which Health and Human Services has declared an emergency or potential emergency.