Professor Sharon Lewin, Professor Kenneth Mayer and Professor Brendan Crabb

Of the estimated 34 million* people living with HIV worldwide, only eight million are currently receiving treatment or full access to antiretroviral drugs.

Whilst antiretroviral chemoprophylaxis drugs have been at the forefront of treating people living with HIV, providing these drugs to HIV negative people in key risk populations to prevent them getting HIV (chemoprophylaxis) are is now being considered as a potential intervention in the transmission of the HIV virus.

Leading international HIV researcher, Professor Kenneth Mayer was invited to Burnet to outline the results of recent studies conducted in the US and South Africa that support proof-of-concept.

Professor Mayer is the Infectious Disease Attending and Director of HIV Prevention Research at the Beth Israel Deaconess Medical Center in Boston; Professor of Medicine at the Harvard Medical School; and Medical Research Director at The Fenway Institute, Boston.

“New antiretrovirals for preventions are being tested in the US and in trials in Africa but these are early studies in what will be a long road,” he said.

Professor Mayer discussed the varying rates of adherence success rates of to antiretroviral chemoprophylaxis between cultures (US/Africa) and the delivery systems (oral, topical, parenteral, and device administered) as key factors.

“In a study in Africa we found that the oral and topical PrEP was ineffective for some women,” he said.

“There is a range of factors that could have contributed – adherence, STIs, pharmacology, viral challenge from partners, genital tract inflammation.”

Timing of medication dosing has also affected efficacy. Studies outlined by Professor Mayer indicate varying compliance by the subjects to participants’ ability to predict sexual encounters affects their ability to and to take the pill with them as a preventative intervention comply with recommended dosing regimens.

However, the use of social media technology - SMS texting - to help those with HIV to adhere to therapies in a US study has revealed increased effectiveness in prompting medication adherence. The randomised trial of SMS v Standard of Care was undertaken at three clinics involving 538 patients who had initiated ART treatment. Such interventions may also assist with HIV chemoprophylaxis.

“Each week a patient would received an SMS message reminding them about drug usage and requiring a response within 48 hours. If there was no response a nurse would follow-up with the patient. Adherence was above 95 per cent.”

Professor Mayer reaffirmed the need to continue to use condoms as the best method of preventing HIV and also STI transmission.

“These antiretroviral medications don’t protect you from STI’s or hepatitis C so that’s an important consideration,” he said.

* figure estimated by UNAIDS 2011.