Risk of HIV transmission during combined ART initiation for HIV-infected persons with severe immunosuppression

Individuals presenting for care with severe immunosuppression typically have high plasma HIV viral load (pVL) and may transmit HIV before and after initiation of combination antiretroviral therapies (cART).

Using risk equations and data collected in the IMEA 040 DATA trial on sexual behaviour and pVL level of 84 HIV-infected patients (23 women), we estimated monthly rates of HIV transmission for each virologically unsuppressed participant (pVL >50 copies/mL) who reported sex with HIV-negative or unknown serostatus (HNUS) partners at cART initiation, 24 weeks (W24) and W48 after; rates were considered negligible for other participants.

At cART initiation, median pVL was 5.4 log10 copies/mL. The percentage of virologically unsuppressed patients decreased, from 100% at cART initiation to 27% (95% CI 16%-43%) for heterosexuals and 8% (95% CI 2%-22%) for MSM at W48 (P < 0.001). The percentage of patients reporting sex with HNUS partners increased between cART initiation and W48, from 23% (95% CI 10%-42%) to 42% (95% CI 25%-61%) for heterosexuals (P = 0.042) and from 41% (95% CI 21%-64%) to 73% (95% CI 52%-88%) for MSM (P = 0.004). Median monthly HIV transmission rates were 0.0540 (IQR 0.0339-0.0742) for MSM and 0.0018 (IQR 0.0014-0.0191) for heterosexuals at cART initiation, and were reduced by 95% (95% CI 87%-100%) for heterosexuals and 98% (95% CI 95%-100%) for MSM as early as W24.

Risk of onward transmission for severely immunosuppressed individuals is high before and within the first weeks of cART, and persists, at a substantially reduced level, beyond 24 weeks of cART for some individuals. Earlier cART and protecting HIV-negative partners until full viral suppression is achieved could reduce HIV transmission.