Laboratory profile, 2012–13 sentinel season.

TIV: trivalent influenza vaccine; HI: haemagglutination inhibition assay.a. H3N2 prototype reference strain recommended as 2012–13 TIV component by the World Health Organization (WHO), as passaged in Madin Darby canine kidney cells; assessed using turkey erythrocytes, validated with guinea pig erythrocytes.b. 2012–13 H3N2 vaccine strain as passaged in eggs and with HA1 sequence identical to the A/Victoria/361/2011 IVR-165 egg-adapted high growth reassortant vaccine strain; assessed based on guinea pig erythrocytes.c. Nineteen of the 129 viruses (19%) manifesting ≥8-fold reduction had been collected from vaccinated participants, comparable to the proportion immunized among H3 detections overall (17%) and among whom 12/19 (63%) showed 16-fold and 4/19 (21%) showed 32-fold reduction.d. 2012–13 TIV component.e. 2011–12 TIV component.