I applied for an ETA in Thailand, and am still waiting to hear back. Trying to be patient... kind of failing a little, though
According to the 2010-2011 magic spreadsheet (https://spreadsheets...Ow6bHdhYA#gid=0), it seems like last years' Vietnam applicants heard around the end of March, which is... nowish. So hopefully you will hear soon about your award status? If he doesn't respond to your second email, I'd give him a call... the medical stuff seems like the sort of thing you want to stay on top of!