Pre-exposure prophylaxis (PrEP) implementation will lead to more frequent HIV testing. Rapid tests are likely to be used especially in resource limited countries, and our aim was to assess their usefulness in the setting of the ANRS IPERGAY PrEP trial.
In the ANRS IPERGAY trial, a 4th generation (4thG) antigen/antibody immunoassay (ARCHITECT HIV Ag/Ab Combo®, Abbott) and/or plasma Viral Load (pVL) (AmpliPrep/COBAS® TaqMan® HIV-1 Test, v2.0) were used for HIV diagnosis at screening and during follow-up. We used stored sera to perform the following tests at the date of diagnosis: pVL, rapid test (VIKIA® HIV1/2, Biomérieux) and HIV-1 western blot (WB, GS HIV-1 Western Blot®, Biorad). We defined 3 stages of HIV infection according to the number of WB antibodies (Ab): chronic (> 7 Ab), recent (1 < Ab < 7) and acute (0 Ab). HIV-1 subtype was determined after phylogenetic analysis of the RT sequence.
Overall, 31 HIV-1-infected patients were diagnosed during the ANRS IPERGAY trial. Stored sera were available for 27 cases of HIV infection. Overall, the 4thG was positive in 25 (93%) (median index 52), rapid tests in 15 (56%) and positive WB (> 1 Ab) in 16 (59%) patients. Median pVL was 5.16 log10 copies/ml. HIV-1 subtype B was identified in 16/25 (64%) cases.
Table.
Sensitivity of rapid tests was 100% (95%CI: 54-100) for chronic infection, 70% (95%CI: 35-93) for recent infection and only 18% (95%CI: 3-52) for acute infection (p < 0.002). Of note, among the 12 positive sera with the 4thG assay but with negative rapid tests, 8 were retested at the follow-up visit (median: 5 days) and 4/8 became positive with rapid tests.
Rapid tests were able to adequately detect chronic infection at screening but largely failed to diagnose acute HIV infection in people at high risk enrolled in a PrEP trial. 4th G assays should be used in settings where PrEP is implemented to avoid missing acute HIV infection, with the risk of selecting drug resistance and of ongoing HIV transmission.