what i don't understand here is, how DNA vaccine can be one shot for flu virus. flu is so Cunning virus because it changes it's antigens so rapidly that memory of our immune system no longer recognizes, means that it leaves no immunity against flu virus. that's why vaccine does not work, because you cant just predict what next antigen structure can be, there are some vaccines i want to mention but scientists just are guessing, sometimes it's successful sometimes isn't. antibodies which block H and N antigens play's vital role in flu virus neutralization. that antibodies are coded by V(D)J recombination, which is hyper mutation in DNA to create multiple variety of antibodies. So means if we use DNA vaccine to teach DNA whats good combination and sequence of next antibody to block flu virus H and N antigens that population of Flu virus may be insufficient to invade. but it will cause selective pressure for flu virus to change antigen forms again. and still DNA vaccine will be inactive. Just my opinion pardon me if i am mistaken :)