HRH3 and influenza: The stalk domain of influenza HA is an attractiveimmune target for developing universal influenza vaccines due to itsconserved nature across HA subtypes, in contrast to the highly variableHA head., Antibodies targeting the HA stalk domainare highly effective in inducing Fc-mediated antibody effector functions,including antibody-dependent cell-mediated cytotoxicity (ADCC). We detected antibody levels against head-removedAic HA (hrH3).