At the end, Spanish flu victim lost blood and so made to feel bad (7)
I believe the answer is:
humbled
'made to feel bad' is the definition.
(humble can mean to make someone feel bad)
'at the end spanish flu victim lost blood' is the wordplay.
'at the end' indicates one should take the final letters.
'lost blood' becomes 'bled' ('bleed' can be a synonym of 'lose blood').
The last letters of 'spanish flu victim' are 'hum'.
'hum'+'bled'='HUMBLED'
'and so' is the link.
(Other definitions for humbled that I've seen before include "Crushed" , "Brought low" .)