if an illness lays someone low, they are unable to do what they usually do for a period of time.
He was at home at the time, laid low with the flu.
(usually passive)
lay (one) low
To render one unable to move or leave their bed. The car accident laid her low for a couple of months.My husband won't be able to come in to work today—he's been laid low by the flu.
lay someone low
Overcome someone, as in He laid him low with one good punch, or The flu laid us low for two weeks. [1300s] Also see lie low.
lay someone low
1 (of an illness) reduce someone to inactivity. 2 bring to an end the high position or good fortune formerly enjoyed by someone.