Surgeon Lieutenant Harry Sullivan was a navy medical officer. In 1980 he was enlisted to a United Nations operation as their medical operation. Afterwards he worked with NATO, before working on various medical procedures.
Harry sat at the bar. He was still struggling to develop a vaccine. He'd hoped, expected even, that with his travels and some access to UNIT files the Brig had given him, he'd have succeeded by now in at least one of them. But nothing.
A man in a blue suit sat down next to him.
"You all right there?" the man asked.
"Fine...not something you can help with."
"Well whatever it is, keep at it. You can get there. Wherever 'there' is. Just don't like unleash a plague on us or something."
The man seemed to know more about Harry than he should. He was about to question who he was, but when he turned to ask the man was gone. He finished his pint and went straight back to the lab to continue his work.
Harry Sullivan developed numerous vaccines, saving countless lives. His name isn't as well known as others, but his contributions to medicine were without peer. Harry Sullivan died in the 1990s.