RT Journal Article SR Electronic T1 Fourth generation point of care testing for HIV: validation in an HIV-positive population JF Sexually Transmitted Infections JO Sex Transm Infect FD BMJ Publishing Group Ltd SP 311 OP 311 DO 10.1136/sextrans-2011-050056 VO 87 IS 4 A1 E Naylor A1 D Axten A1 F Makia A1 C Tong A1 J White A1 J Fox YR 2011 UL http://sti.bmj.com/content/87/4/311.abstract AB