Poll: I have had not above two _____ sickness since my arrival in this country.

Toby

You'd say the -s in the singular, so it should be -s'.

Vidableek

I disagree. Don't we only add an apostraphe if it's possesive, or if it's a contraction for "week is", and not for the plural?

Stuee

It is possessive AND plural, hence the apostrophe after the 's'.

Brunilde

It is correct the plural only:... two weeks sickness...

ant

Saxon genitive of two weeks is two weeks'