Our office has been billing the 87804 as a quantity of 1 until recently when I discovered our test are for both strains A&B. I have been billing for this and only changing the quantity and adding notes that it is for both A&B and the payer's have been paying on this. However, a colleague recently suggested I use a modifier with this as well but was not certain what modifier should be used. Is this correct, should a modifier be added, and if so, which one? Thanks so much for the help!