The Wensleydale School is the latest in the district to close due to the norovirus.
The school has written to parents today to tell them it will e shut on Thursday and Friday this week.
School business leader Nicki Geater said: “Due to an outbreak of norovirus amongst our staff, we regret that school will be closed tomorrow and Friday.
“We have staff dropping like flies this morning, but we think we can just about manage to get through today.
“We are relying on supply staff today, however agencies are unable to commit for the rest of the week, due to the number of staff they themselves have off work sick.
“We apologise for any inconvenience caused.”
Last week, Risedale College shut for several days.
Several Catterick Garrison secondary schools also closed temporarily.