Vim, How to substitute tab with comma

Q: How to substitute tab with comma with vim ?

We have a file like that
q test
2 sdd
3 netst
4 sdfd
5 nestde
6 mailqre
7 netsta
8 whatr
9 masterq
10 majsd
11 rest
12 mssdjswd
13 uwefsdc
14 jurtewq
…….

I will use substitute command to change every occurrence in the whole file.
:%s/\t/,/g

Rezult:

q,test
2,sdd
3,netst
4,sdfd
5,nestde
6,mailqre
7,netsta
8,whatr
9,masterq
10,majsd
11,rest
12,mssdjswd
13,uwefsdc
14,jurtewq