adminMitchell Warren Correspondent
On May 18 1997, US President Bill Clinton committed to developing an AIDS vaccine within 10 years. Nearly 20 years later, we still don’t have one.
And every year in Zimbabwe, 69 000 people become newly infected.
But AIDS vaccine advocates do have a lot to celebrate in the field of AIDS vaccines and HIV prevention generally.
For much of the first 30 years of the epidemic, there have been essentially two strategies to prevent sexual transmission of HIV: Abstinence and condoms.
But in the past decade, we have had important advances. For example, we now know that anti-HIV drugs not only keep HIV-positive people healthy, they work so well that a person on successful HIV treatment has very little chance of passing the virus to a sexual partner. Treatment is also prevention. Voluntary medical circumcision also greatly reduces a man’s risk of acquiring HIV, an effect that actually seems to strengthen over time; fewer HIV-positive men means less HIV risk for women and the community at large.
In addition, multiple studies of pre-exposure prophylaxis (PrEP) have shown that people at risk of HIV can take a particular anti-HIV medication to prevent infection — when they take the pills consistently.
We need to make sure that all of the HIV prevention methods we have today reach the people who need them.
At the same time we need to continue the investments in research to ensure even more prevention options are developed and made available. An AIDS vaccine remains essential to ultimately ending the epidemic. Happily, today on HIV Vaccine Awareness Day 2015, we can report progress.
In 2009, a clinical trial in Thailand showed for the first time that an experimental vaccine modestly reduced the risk of HIV transmission. And early this year, a trial to test a modified version of that vaccine — redesigned with the goal of making it more protective —started in South Africa. If this trial finds positive results, in two years a large-scale efficacy trial would begin, which could eventually lead to a licensed vaccine. This year we will also see a significant step by industry: Janssen, part of Johnson & Johnson, is launching its own international clinical trial to test a vaccine developed with partners.
We haven’t seen a large vaccine developer invest in clinical trials for AIDS vaccine without public or charitable contributions in almost a decade.
This vaccine strategy incorporates a strategy that researchers hope will protect against the many different types of HIV that circulate around the world.
Further upstream research involves the discovery that some people living with HIV create particularly potent antibodies that are able to “neutralise” many different HIV strains. A handful of these “broadly neutralising antibodies” or bNAbs, have been isolated from blood samples donated by HIV infected individuals.
Scientists are now planning to test whether direct transfer of the most potent antibodies could prevent, treat, or even be part of a cure for HIV when infused directly into the blood stream.
Early clinical trials testing this process, known as “passive immunisation”, currently involve monthly intravenous blood transfusions lasting 30 minutes or more.
But the aim is to reduce the time and frequency of infusions to perhaps quarterly or twice a year. A recent small study using one of these potent antibodies found that virus levels dropped significantly among participants living with HIV, an effect that lasted one month after only one dose.
Scientific, research, and academic meetings and journals have been buzzing with talk about bNAbs for the past few years, especially in the vaccine research community. But the reality is, bNAb research is in very early stages, there are many questions and unknowns and the science is extremely difficult to understand and explain to non-scientists.
As this work moves forward, scientists and funders need to collaborate with advocates and community stakeholders to ensure that adequate resources are allocated to communications and community engagement. With all of the excitement around bNAbs and two different vaccine strategies now entering clinical trial phases in Africa, the robust community of African AIDS researchers must be at the table before decisions are made.
Online Reporter