Zavim 5:3

The food or drink at the end of the previous mishna remain ritually clean because the Sages have taught that whatever carries or is carried on a zav’s mishkav (something on which one lies) remains ritually clean except for a person. Whatever carries or is carried on a neveila (carrion) remains ritually clean except for a person who moves it; Rabbi Eliezer says also one who carries it. Whatever carries or is carried on a corpse remains ritually clean except for what overshadows it and a person when he moves it.

Zavim 5:4

If part of a ritually unclean person rests on a ritually clean person, or vice versa, or if things connected to a ritually unclean person rest on a ritually clean person, or if things connected to a ritually clean person rest on a ritually unclean person – in all of these cases, the ritually clean person is rendered unclean. Rabbi Shimon says that if part of an unclean person is on a clean person, he’s unclean but if part of a clean person is on an unclean person, he remains clean.