Cross-strain influenza A(H3N2) antibody responses measured by HI assay.^*

HI = hemagglutination inhibition; TIV = trivalent inactivated influenza vaccine. Note that undetectable titres <10 were assigned a value of 5. *Unit of analysis pooled sera from 5 mice, thus 10 pools from 50 mice were available for this experiment. aMeasured two weeks after specified TIV dose; bMeasured two months after specified TIV dose. †Compared to pre-immunization for priming antigens; compared to immediately preceding titre for boosting antigens. Brisbane-like = A/Uruguay/716/2007(NYMC 175C)(H3N2) considered antigenically equivalent to the WHO recommended A/Brisbane/10/2007(H3N2) component of the 2008–09 northern hemisphere TIV. Perth = A/Perth/16/2009(H3N2)-like, component of the northern hemisphere 2010–11 TIV.