First thing Harry and Severus saw after setting a foot in new world was pile of dead people, and not-all-dead people crawling on the street. Harry almost face-palmed.

'Oh please, not again.'

'I told you we have to go for the second coordinate.'

'Last time you did, we went to the bloody frozen world. And what did we get? Pack of five-feet ice-wolves attacking us! At least those things don't attack us.'

Severus quickly went to the nearest horde of undeads to analyze the bodies.

'There is no magical residue.'

'Are you saying they are due to muggle disease or something? Like zombies but not Inferi?'

'Precisely, and there is no single magical residue in this world aside from us.'

'Bloody hell, this is a nightmare. How do we survive ten years here? We would be bored to death.'

'We decided we would see for curing a disease like this. Knowing our luck, if we leave it like this we would be coming here again.'

Yes, this was not the first time they encountered something like this. Once or twice they had ignored all the problems, just holed up somewhere they could quietly live, and exited that universe as fast as possible. That ten years were just with research, wandering around, and getting peculiar ingredients for Severus's work. But for all their bad luck, they had returned to that particular universe. And boy, it was horrible. After all, ten years with groaning and roaming dead people was tad boring. Then they decided they would find the cure and save some population to come back to. Dystopian world with few people was better than a world with no people at all.

'Where would be the nearest research center? Or just university with any laboratory would be good.'

'If we can capture a living person then he or she can point us. You know, I am not from here.' Harry deadpanned.

Finding living people was not that difficult. Since they were in the big city area, all they had to do was to scan the area for any human signal. They spotted a tired looking man in an abandoned building, and after quick rummaging through his memory, they found the exact place. The Centers for Disease Control and Prevention.