Reply to Niu and Drain.

Competing Interests: Potential conflicts of interest. D. V. G. has received consulting fees from Gilead and institutional grants or contracts from the National Institutes of Health. P. L. A. has received consulting fees from Merck, ViiV, and Gilead and research support from Gilead paid to his institution. M. A. M. reports royalties from Elsevier for co-editing a textbook; honoraria for speaking engagements from Bio-Rad; travel support from Mass Spectrometry & Advances in the Clinical Lab (MSACL) and American Association of Clinical Chemistry (AACC); and participation on the AACC Board of Directors; and has received research support from Merck, ViiV, Ridgeback, and Gilead paid to his institution. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.