P52.01
Background: Most new adult HIV infections in Africa are acquired from steady partners and WHO recommends that couples be tested and counseled together as an HIV prevention strategy. ART reduces transmission from the HIV+ partner in discordant couples.
Methods: CVCT programs established in 70 Zambian government clinics include follow-up testing for discordant and concordant negative (M-F-) couples. We assess seroincidence in discordant couples, confirm linkage through sequencing, and compare rates before (antigen positive at CVCT or seroconverting within 6 weeks of CVCT) and after CVCT and on or off ART. We also compare the overall number of seroconversions in discordant and M-F- couples, and compare the cost of averting one HIV infection through CVCT vs. TasP.
Results: 148,839 couples were tested, of whom 17,619 were discordant (3,229 or 18.3% on ART at the time of CVCT) and 109,677 were concordant negative (M-F-). Of 112 seroconversions, 62 occurred in discordant (5.4/100PY, 95% CI 4.1-6.9) and 50 in M-F- (0.98/100PY, 95% CI 0.73-1.30) couples. Among discordant couples, excluding infections acquired from outside partners, the rate before CVCT was 8.9/100PY (6.5-11.8) compared with 2.3/100PY after CVCT (95% CI 1.2-3.8. The overall transmission rate in discordant couples not on ART was 8.6/100PY (95% CI 5.6-12.4), compared with 3.7 (95% CI 2.2-5.9) when the infected partner was on ART. Among M-F- couples, incidence was 1.4/100PY (95%CI 1.0-1.9) before and 0.12/100PY (95% CI 0.01-0.44) after CVCT. Using program costs and rates, the cost of averting one infection with CVCT was<$500, compared with an annual cost of>$10,000 for TasP in discordant couples.
Conclusions: CVCT prompted a 74% reduction in new infections among discordant couples and a 91% reduction in M-F- couples. Among discordant couples TasP was associated with a 58% reduction. The combination of CVCT+TasP in discordant couples is ideal, but CVCT has significant impact even when TasP is not available, and at 5% of the cost of TasP.
