A universal flu vaccine seems promising with at least 8 on-going phase II/III clinical trials on it (https://asm.org/Articles/2019/August/A-Universal-Influenza-Vaccine-How-Close-Are-We). Hopefully, it won't turn out like HIV where there are over 5 failed vaccine trials. Anyway, great article conveying the point that flu vaccines, despite not very effective in some seasons, is the best we have in fighting the flu.