Countif with activecell.row variable for range?

Hi... I'm trying to loop through some data, adding a formula for a COUNTIF function, but am having trouble with the syntax. Can one of you lend a hand?

The sheet name that the formula goes into is "NRSS-1"
The sheet name which has the values to be counted is "E3"
The column in "E3" which has the values to be counted is B
When entered manually, the formula I'm using looks like this:
=COUNTIF('E3'!B:B,A2)
However, I want to replace the "A2" with "activecell.row"

Any guidance would be appreciated!