I'll gladly admit I laughed a little seeing this as I immediately said "support group for hep v. vampires" and thought about the silliness of that just 48 hours after killing those hep v vampires in Fangtasia. But then I had a little closer look and it might actually be a hospital and as we see hep v vampires sitting there, it must be a hospital for supes or vampires, so perhaps visiting Dr. Ludwig or will we see someone new? No matter what, it's 48 hours after the Fangtasia killing and suddenly all hep v vampires are nice and seeking help? Why even bother with that first group at all? And are they there during the day? The bleeds we see from the vampires' ears suggests that they are.
I guess Bill didn't like what he heard as someone blows up as he leaves, or is that just a lucky coincidence? If it is the doctor, it's not Dr. Ludwig as only vampires pop like that. So why is the hep v progressing as quickly as it is in Bill's body?
I think the reason the virus spreads so quickly in Bill is easy. It's not because of Sookie's tainted blood being the source of the virus, it just activated the virus in Bill that he got from feeding Nora in S6E7.
The virus didn't spread then as he had both Lilith's and Warlow's blood when that happened. The virus remained dormant even after Warlow died. But when the virus was reintroduced with Sookie's blood, it triggered the original virus into action and that's why we see this rapid progression with Bill, it is the original strand and not the mutated virus. Bill should have known about Sookie potentially being a carrier as she had a big band aid over the wound she got hep v blood into in S7E3. He still fed from her.
But this is my own interpretation, it's possible the writers will blame Sookie and no one else.