A mathematical modeling study for HPTN 083 demonstrated both forms of PrEP vs not taking anything remained efficacious in preventing infection.
Investigators wanted to estimate the impact of PrEP regimens among men who have sex with men (MSM) in Atlanta, Georgia. They performed a mathematical modelling study for HPTN 083, and looked at long-acting injectable cabotegravir (CAB) and daily oral tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) vs not taking PrEP.
The investigators developed a MSM HIV transmission model calibrated to Atlanta-specific data on HIV prevalence and PrEP usage. They looked at the percentage of uninfected MSM on PrEP, and assumed only PrEP-indicated MSM used PrEP.
“CAB effectiveness (efficacy × adherence) of 91% was estimated using data from HPTN 083 and previous TDF/FTC trials,” the authors wrote. “We estimated HIV infections averted over 5/10 years if TDF/FTC use were maintained, or if all TDF/FTC users switched to CAB in January 2022 (vs. no PrEP or continued TDF/FTC use). CAB scenarios with 10%/20% more users were also considered.”
“We predicted TDF/FTC at current usage (∼28%) would avert 36.3% of new HIV infections (95% credible interval 25.6–48.7%) among all Atlanta MSM over 2022–2026 vs. no PrEP,” the investigators wrote. “Switching to CAB with similar usage may prevent 44.6% (33.2–56.6%) infections vs. no PrEP and 11.9% (5.2–20.2%) infections vs. continued TDF/FTC.”
The results were published in The Lancet Regional Health Americas.
The investigators included estimates of the Ending the HIV Epidemic (EHE) goals. The federal EHE initiative is an ongoing effort to reduce the number of new HIV infections in the United States by at least 90% by 2030.
They predicted that if they could increase the long-acting injectable usage up 20% that they could increase the impact over daily oral PrEP to 30% over a four period. And this would have a positive effect on EHE goals with 47% fewer new infections by 2025 and 54% fewer infections by 2030.
The investigators said reaching the 2030 EHE goal would require 93% long-acting injectable usage.
The South and HIV Incidence
The south has been especially challenged with HIV incidence rates. When looking at different regions of the US, the CDC reports that the south accounted for 51% of the new HIV diagnoses in 2020. This is the highest of all regions in the country and within those statistics, Georgia has the highest rate of diagnoses at 22 people diagnosed per 100,000. And in terms of US cities, Atlanta has been in the top 10 of the highest rates of new HIV diagnoses for a number of years.
For those who are diagnosed with HIV, care for them has inherent inequities.
One of the distinctions of people with HIV (PWH) is the dichotomy between those with access to care and those who do not. In an interview with Contagion a couple of years ago, Melanie Thompson, MD, principal investigator of the AIDS Research Consortium of Atlanta (ARCA) talks about the continuum of care challenges between the 2 cohorts. In the one group, PWH have access to care, ART, and are the population who is getting older and dealing with age-related issues like comorbidities, frailty, and neurocognitive decline.
“The other world where I live in Georgia, people are still dying from AIDS,” Thompson said. “It is not as if we have conquered HIV…We have people hospitalized with the old AIDS infections and malignancies that have almost been eliminated by antiretroviral therapies. If you look at the populations who continue to be the most affected, they are driven by factors such as structural racism, stigma, discrimination, and lack of access to social services,” Thompson said.