Come down with= become sick/ बीमार
I think I am coming down with the flu.
Fight off= free from an illness/ एक बीमारी से मुक्त
The world is trying to fight off coronavirus.
Come to= become conscious/ होश में आना (जागना)
When he came to, he was lying on the floor with his hand tied behind his back.
Pass out= faint or lose consciousness/ बेहोश
People passed out because of heat.
Get over= recover from something/ किसी चीज से उबरना
It has taken me ages to get over the flu.