Beside the main characters of the show and those who have been introduced during the seasons, there is an actress who has been there from the very beginning and has never left the scene: the nurse!
From episode 1, every single time a nurse appears, she is interpreted by the same actress: Vernee Watson.
From the Sperm Bank, to the hospital where Howard is brought because of the arm robot stuck on his private parts, to the room where Sheldon's sick barber is held, Althea (as revealed in her name tag) is always the portrait of The Big Bang Theory nurse!
In multiple occasions Sheldon has expressed his discomfort with activities that involve "touching" a human being.
Even he doesn't have a "touch phobia", as stated in the episode "The Benefactor Factor" to the president of the university dr. Siebert:
"It's not a touch phobia, it's a germ phobia. If you'd like to go put on a pair of latex gloves, I'll let you check me for a hernia."
he thinks that massaging his back with his own hand:
"Still seems like a lot of unnecessary touching"
This is the Sheldon Cooper we get to know during the seasons. Truth is, in the very first episode of the show, that Leonard defines him as a "Semi Pro" in masturbation activities (they were at the sperm bank to donate their sperm and use the money to get a faster internet connection!).
