China
Africa
Explore chapters and articles related to this topic
Recent Advances In HIV/AIDS
Published in Anne George, K. S. Joshy, Mathew Sebastian, Oluwatobi Samuel Oluwafemi, Sabu Thomas, Holistic Approaches to Infectious Diseases, 2017
Another recent focus that has been on a series of small Phase Ib studies that aim to address basic science questions and generate new hypotheses regarding vaccination strategies and their associated immune responses. Vaccine candidates that progress into efficacy trials have the greatest potential to advance the field and generate immune correlates of protection. The largest ongoing HIV vaccine trial, known as HVTN 505, is a Phase IIb trial testing a vaccine regimen developed by the Vaccine Research Center at NIAID. The regimen, a DNA prime followed by a recombinant adenovirus type 5 (Ad5) boost, was found to be the most immunogenic in any HVTN study to date. The results of this trial, together with the large amount of immunogenicity data being collected, are expected to provide valuable information for future vaccine developments.
Regression analysis of case-cohort studies in the presence of dependent interval censoring
Published in Journal of Applied Statistics, 2021
Mingyue Du, Qingning Zhou, Shishun Zhao, Jianguo Sun
One real study that motivated this investigation is the HVTN 505 Trial to assess the efficacy of a DNA prime-recombinant adenovirus type 5 boost (DNA/rAd5) vaccine to prevent human immunodeficiency virus type 1 (HIV-1) infection (Fong et al. [8]; Hammer et al. [10]; Janes et al. [14]). It is well-known that HIV-1 infection is deadly as it causes AIDS for which there is no cure and thus it is important and essential to develop a safe and effective vaccine for the prevention of the infection. The original study consists of 2504 men or transgender women who had sex with men were examined periodically, thus yielding only interval-censored data on the time to HIV-1 infection. For each subject, the information on four demographic covariates, age, race, BMI and behavioural risk, was collected, and in addition, for a subgroup of HIV infection cases and non-cases, a number of T cell response biomarkers and anti-body response biomarkers were also measured. One goal of the study is to determine or identify the important or relevant covariates or biomarkers for HIV-1 infection.
Prophylactic HIV vaccine: vaccine regimens in clinical trials and potential challenges
Published in Expert Review of Vaccines, 2020
Punnee Pitisuttithum, Mary Anne Marovich
For example, the size of HVTN 505 was expanded from an originally planned target of 1,350 participants to 2,200 for two reasons: to evaluate vaccine efficacy in preventing HIV acquisition following the results of the RV144 trial in Thailand [8] (the original design focused on the endpoint of post-infection viral load setpoint), and to accommodate PrEP usage up to 20% of the period participants were at risk (reflecting 20% of participants using PrEP consistently or a greater proportion of participants using PrEP, but not for the entire study period). Current vaccine and bNAb efficacy studies allow PrEP usage and are powered to detect acquisition effects up to certain levels of PrEP uptake. Very high uptake of PrEP by choice or by required PrEP usage in prevention studies will necessitate very large sample sizes and may have incidence levels similar to those of low/no risk volunteers. Important questions regarding use of active controls, study populations, standard of prevention, primary or surrogate endpoints, biomarkers, and use of adaptive type trial designs will need to be addressed moving forward [32]. This area needs to be explored and social science research should be encouraged to address outstanding questions.
Accelerating HIV vaccine development using non-human primate models
Published in Expert Review of Vaccines, 2019
Mohammad Arif Rahman, Marjorie Robert-Guroff
Early results of the HVTN 505 trial showed that vaccine-specific CD4+ and CD8+ T cells were elicited in 61.5% and 64.1% of vaccinees, respectively, and all the vaccinees developed IgG antibodies to HIV Env. However, due to lack of vaccine efficacy (p = 0.28), the trial was stopped [74]. Here, as with the STEP study, the SIVmac251 model better predicted the trial outcome. Protection of vaccinated macaques from SIVsmE660 infection has been associated with low levels of neutralizing antibody [73]. SIVsmE660 isolates are highly sensitive to neutralization, whereas SIVmac251 and SIVmac239 are much more resistant [75]. An NHP model that can accurately predict results of clinical trials will have to consider many properties of potential challenge viruses.