Medical education after the first decade of democracy in South Africa.

No abstract available

Assessing progress with HIV incidence in national cohorts.

CAPRISA., 2017.Abstract available in pdf

HIV vaccines and immunity.

No abstract available

Combination HIV prevention options for young women in Africa.

CAPRISA, 2016.Abstract available in PDF file

Ritonavir/saquinavir safety concerns curtail antiretroviral therapy options for tuberculosis–HIV-co-infected patients in resource-constrained settings.

CorrespondenceNo abstract available

An adaptive design to bridge the gap between phase 2b/3 microbicide effectiveness trials and evidence required for licensure.

Background. Vaginally and rectally applied microbicides are being developed to help prevent sexual acquisition of HIV. Due to the lack of surrogate outcomes, the path toward licensure typically moves directly from expanded safety studies to expensive Phase 2b/3 trials with rare incident infection outcomes. The need to confirm an initial trial’s significant finding can lead to serious delays in implementing essential programs to reduce the spread of HIV. Purpose. To propose an adaptive design where a Phase 2b/3 study powered to detect a clinically meaningful effect with evidence of one trial (observing one-sided p < 0.025) is allowed to expand by a prespecified, feasible amount if interim data suggest the chance of further achieving a more robust evidence threshold ( p < 0.001, potentially sufficient for licensure from a single trial) is promising. Methods. As an example, prespecified conditional power criteria are used to determine whether a 90-event trial with 90% power to detect a 50% reduction in risk should be expanded to 130 events. Asymptotic results and simulations are used to assess false-positive error rates and other operating characteristics of the design. Results. False-positive error rates can be controlled at the desired 0.025 and 0.001 levels with appropriate choice of critical values or expansion criteria. The chance of achieving robust evidence can approach that of a 130-event trial with traditional stopping boundaries (controlling a = 0.001) but with substantially lower expected size for plausible effectiveness levels. Limitations. Conditional power calculations assume the interim estimate of effect is an unbiased estimate for the remainder of the trial, an assumption which may not hold if product adherence varies over time. Observing a measure of effect with p < 0.001 may not be sufficient for licensure. A decision to expand the trial would be informative to investigators regarding the interim effect size. Conclusions. A moderate increase in trial size can make the difference between a study with good power to detect a clinically meaningful effect and one which may reasonably obtain the robust evidence required for regulatory bodies and public health programs to consider making a new microbicide available to persons at risk of HIV infection. The proposed design allows for this possibility while not requiring investigators to make an up-front commitment to a prohibitively large trial

TB treatment outcomes following directly-observed treatment at an urban outpatient specialist TB facility in South Africa.

The treatment of 450 consecutive new patients with pulmonary TB was evaluated to determine outcome following directly-observed treatment. In all,176 (39.1%) patients were cured, 23 (5.1%) completed treatment, 80 (17.8%) defaulted treatment, 24 (5.3%) died, 54 (12.0%) were lost to follow-up and 93 (20.7%) were transferred out. Increasing age was significant for death. Males were more likely to default and those with negative pretreatment sputum smears and those who were unemployed were more likely to be lost to follow-up.The overall treatment success rate remains low. Our data suggests that greater emphasis is needed to improveTB treatment success

Increasing burden of pulmonary tuberculosis in young women.

Scientific letter.No abstract available

Changes in natural killer cell activation and function during primary HIV-1 infection.

Background. Recent reports suggest that Natural Killer (NK) cells may modulate pathogenesis of primary HIV-1 infection. However, HIV dysregulates NK-cell responses. We dissected this bi-directional relationship to understand how HIV impacts NK-cell responses during primary HIV-1 infection. Methodology/Principal Findings. Paired samples from 41 high-risk, initially HIV-uninfected CAPRISA004 participants were analysed prior to HIV acquisition, and during viraemic primary HIV-1 infection. At the time of sampling post-infection five women were seronegative, 11 women were serodiscordant, and 25 women were seropositive by HIV-1 rapid immunoassay. Flow cytometry was used to measure NK and T-cell activation, NK-cell receptor expression, cytotoxic and cytokine-secretory functions, and trafficking marker expression (CCR7, α4β7). Non-parametric statistical tests were used. Both NK cells and T-cells were significantly activated following HIV acquisition (p = 0.03 and p<0.0001, respectively), but correlation between NK-cell and T-cell activation was uncoupled following infection (pre-infection r = 0.68;p<0.0001; post-infection, during primary infection r = 0.074;p = 0.09). Nonetheless, during primary infection NK-cell and T-cell activation correlated with HIV viral load (r = 0.32'p = 0.04 and r = 0.35;p = 0.02, respectively). The frequency of Killer Immunoglobulin-like Receptor-expressing (KIRpos) NK cells increased following HIV acquisition (p = 0.006), and KIRpos NK cells were less activated than KIRneg NK cells amongst individuals sampled while seronegative or serodiscordant (p = 0.001;p<0.0001 respectively). During HIV-1 infection, cytotoxic NK cell responses evaluated after IL-2 stimulation alone, or after co-culture with 721 cells, were impaired (p = 0.006 and p = 0.002, respectively). However, NK-cell IFN-y secretory function was not significantly altered. The frequency of CCR7+ NK cells was elevated during primary infection, particularly at early time-points (p<0.0001). Conclusions/Significance. Analyses of immune cells before and after HIV infection revealed an increase in both NK-cell activation and KIR expression, but reduced cytotoxicity during acute infection. The increase in frequency of NK cells able to traffic to lymph nodes following HIV infection suggests that these cells may play a role in events in secondary lymphoid tissue

The future role of rectal and vaginal microbicides to prevent HIV infection in heterosexual populations: implications for product development and prevention.

Objectives. To compare the potential impact of rectal (RMB), vaginal (VMB) and bi-compartment (RVMB) (applied vaginally and protective during vaginal and anal intercourse) microbicides to prevent HIV in various heterosexual populations. To understand when a RMB is as useful than a VMB for women practicing anal intercourse (AI). Methods. Mathematical model was used to assess the population-level impact (cumulative fraction of new HIV infections prevented (CFP)) of the three different microbicides in various intervention scenarios and prevalence settings. We derived the break-even RMB efficacy required to reduce a female’s cumulative risk of HIV infection by the same amount than a VMB. Results. Under optimistic coverage (fast roll-out, 100% uptake), a 50% efficacious VMB used in 75% of sex acts in population without AI may prevent -33% (27, 42%) new total (men and women combined) HIV infections over 25 years. The 25-year CFP reduces to -25% (20, 32%) and 17% (13, 23%) if uptake decreases to 75% and 50%, respectively. Similar loss of impact (by 25% - 50%) is observed if the same VMB is introduced in populations with 5% - 10% AI and for RRRAI=4-20. A RMB is as useful as a VMB (ie, break-even) in populations with 5% AI if RRRAI=20 and in populations with 15% - 20% AI if RRRAI=4, independently of adherence as long as it is the same with both products. The 10-year CFP with a RVMB is twofold larger than for a VMB or RMB when AI=10% and RRRAI=10. Conclusions. Even low AI frequency can compromise the impact of VMB interventions. RMB and RVMB will be important prevention tools for heterosexual populations