I'm still stuck waiting for publication of the relevant journal paper, but I now have a copy of poster presented by PowderMed earlier this year.
The summary: with 1, 2, and 4 microgram injections of an H3 gene vaccine via gene gun, PowderMed has shown that even the single microgram dose was safe and generated an anti-influenza antibody response. Each dose was trialed on a group of 12 volunteers. "The titres achieved at day 21 of the 4 microgram dose group were sufficient to meet the requirements of the CHMP [Committee for Medical Products for Human Use of Europe] for licensing of annual influenza vaccines." Thus falls the "primate barrier" to DNA/gene vaccines.
As I understand it, human challenge trials for H3 Panama influenza will begin early next year. So the pieces are falling into place, but there seems to be so much unfounded resistance against DNA/gene vaccines that it may take a painfully long time just to get funders and regulators tuned in to the possibilities.
I'll post more here when additional trial data is no longer embargoed.