The universal influenza vaccine developed by Sumitomo Pharma Co., Ltd. is based on the post fusion hemagglutinin (HA) antigen adjuvanted with DSP-0546LP, a toll-like receptor 7 (TLR7) agonist. The post fusion HA antigen exposes occluded epitopes common to a wide range of influenza viruses. Immunization of immunocompetent humanised mice with this post fusion HA antigen adjuvanted with DSP-0546LP has been shown to induce human cross-reactive antibodies that protect against multiple influenza viruses. A phase I clinical trial is starting in Europe in 2024.