CREDIT: AP Photo/Penn Medicine, Peggy Peterson Photography
A series of new discoveries made public this week could have significant implications for the treatment of HIV and new strategies for how to prevent its spread. Indeed, they signify a growing shift in how society understands the virus itself.
1. People With Undetectable Viral Loads Do Not Transmit The Virus
There is still no cure for HIV, but treatment methods have improved to the point that many people living with the virus are able to use antiretroviral therapy (ART) medication to reduce their viral load to “undetectable” levels. This means that an individual’s viral load is being maintained at a level that a viral load test is not able to measure.
A new study (“The PARTNER study“) suggests that it’s nearly impossible for people with undetectable viral loads to infect others with HIV through either vaginal or anal sex. The study followed nearly 900 couples who were serodiscordant (one partner was HIV positive and one was HIV negative) and undetectable and who were regularly having sex without condoms. After an estimated 16,400 occasions in which the same-sex male couples had sex and 14,000 in which the different-sex couples had sex, there was not one incidence of transmission.
There were some people in the study who became HIV positive, but genetic testing proved in every case that the virus came from someone other than the partner in the study. Likewise, the fact that no transmission occurred does not mean that transmission is impossible. Researchers estimate that the chances of transmission are about 2 percent for vaginal sex with ejaculation, 2.5 percent for receptive anal sex (in which the negative partner is bottoming), and 4 percent for receptive anal sex with ejaculation.
This speaks to the importance of a “treatment as prevention” strategy that encourages testing and treatment. People who find out that they are HIV positive can use medication to manage their viral load and minimize — if not virtually eliminate — the risk of transmission to others.
2. Gene Modification Could Possibly Present A New HIV Treatment Option
The initial results of a study from the National Institute of Allergy and Infection Diseases find that gene modification could be safely used to help HIV positive individuals control their viral loads. In the study, individuals who were controlling their viral loads with medication volunteered to allow their T-cells to be collected and genetically mutated to be resistant to HIV infection. The cells were then replicated and infused back into the patients.
The patients then stopped their antiretroviral therapy for 8-12 weeks to assess whether the modified cells would maintain their resistance, and they did. In most of the patients, only about a fifth of their genes were mutated in the experiment, but one volunteer agreed to have half of his mutated, and after 12 weeks without ART, that individual’s viral load remained undetectable.
This is only a preliminary study, but one with promising results. Genetic modification could help individuals who are HIV positive use their own cells to resist the spread of the virus in their bodies — and thereby to others as well. This could reduce the demand for ART and help expand access to treatment options.
3. A Monthly Shot Could Held Protect People From HIV Infection
Though condoms are the only prevention method that has the potential to literally block exposure to HIV, they are not the only method of preventing infection and not necessarily the most statistically effective. Research has shown that if HIV-negative individuals take a regiment of medication that was originally designed for treating HIV, they can drastically reduce their risk of infection — by up to 99 percent according to one study. This is known as pre-exposure prophylaxis, or PrEP.
PrEP’s effectiveness is independent of condom usage, meaning that both are part of a toolkit to reduce HIV infection. Some insurance companies are already covering PrEP, because it’s cheaper for them to prevent HIV than to treat it. PrEP’s effectiveness, however, relies upon individuals taking it every day, even when they are not sexually active, and it is not without side effects, such as nausea. A new study from the Centers for Disease Control and Prevention (CDC) shows promise that the same preventative effect could soon be achieved through a shot that individuals only have to receive monthly — or maybe even only every three months.
The study was conducted on a small group of macaque monkeys, who were given the shot once every four weeks, but who were exposed to a human-monkey version of HIV twice a week during the 11 week run of the experiment. All of the monkeys who received the placebo contracted the virus, but none of the monkeys who received the drug did. A second study tested to see just how long a single shot of the drug might last, and found that the dosage could be increased to protect the monkeys from infection for about 10 weeks on average.
Should such a treatment ever become available for human usage, individuals might more reliably follow through on a shot every few months instead of a daily pill, increasing the likelihood that they will protect themselves from infection. Testing is already underway to see if the same drug can be used as a treatment method for people who are HIV positive.
The growing discoveries about HIV present new opportunities for individuals who are both positive and negative to take steps to reduce the risk of infection. Still, boundaries remain that stigmatize people with HIV and discourage testing, such as laws that criminalize transmission of the virus. Testing, itself, has been found to help reduce the risk of transmission, and the results of these studies will allow individuals to make better informed decisions about how to use their test results to continue reducing that risk.