[R] Parenthesis recognition with grep

[Sébastien]

Dear R-users,

I need to dynamically recognize the index of a given string myStr in a 
vector of string. The problem is that myStr might contain parenthesis, 
causing grep not to recognize it the way I want (see below). The help 
mentions that the pattern used by grep should be in the POSIX format... 
I guess the problem is here; unfortunately, I am not familiar with the 
subtleties of the POSIX format

ex:
myStr <- "YD(001)"
headers <-c("TD", "YD(001)", "YD(002)", "T", "Y(001)", "Y(002)")
grep(myStr, headers)

How should I modify my grep call to get the match right?

Thank you for your help,

Sebastien