Zimbabwean scientists, in collaboration with a global consortium of researchers, are preparing to conduct the country's first ever HIV vaccine trial as part of the global effort to find a lasting solution to the spread of HIV. "The vaccine to be tested in Zimbabwe is a preventive vaccine that will be administered to HIV-negative people," according to clinical trials coordinator Dr Portia Hunidzarira.
"Those already taking antiretroviral treatment (ART) are not eligible," she explained, referring to the drug used to suppress the virus among people who are already living with HIV.
Focus on HIV-negative people
Hunidzarira said the trial aimed to determine whether the vaccine could prevent HIV-negative people from contracting the virus. It will also gauge the safety of new vaccine products and regimens while measuring the immune response among trial subjects. Dr Lynda Stranix-Chibanda, a paediatrician at the University of Zimbabwe, is leading the initiative on behalf of the HIV Vaccine Trials Network (HVTN) in conjunction with the University of Zimbabwe and University of California San Francisco (UZ-UCSF) Collaborative Research Programme.
The HVTN is a publicly funded multi-disciplinary global consortium of scientists tasked with facilitating the development of HIV vaccines. Stranix-Chibanda said the trials would likely be conducted in June 2015 at the Seke South Clinic in the town of Chitungwiza, located about 30km south of Zimbabwe's capital Harare.
The vaccine to be tested is based on one used in Thailand's RV144 trial which was moderately successful at preventing new HIV infections among vaccinated adults.
Stranix-Chibanda added that RV144 had been modified for a sub-strain of the virus called Clade CHIV which is found in southern Africa. She went on to note that the HVTN107 vaccine, which will be tested in Zimbabwe and other southern African countries, had seen the addition of another booster, including an adjuvant (a pharmacological and/or immunological agent that modifies the effect of other agents) to test the response as compared to RV144.
RV144 had a six-month vaccination schedule while HVTN107 will have a 12-month schedule.
The trials in Thailand, which were reportedly administered to 16,000 adults, were 60 per cent effective at one year and 31 per cent effective at three years.
"The next phase of the programme will involve the selection of the best candidates, further research to assess the effectiveness of the drug, and - if successful - licensure for use," Stranix-Chibanda said.
According to Emilder Chihota, a community educator participating in the UZ-UCSF Collaborative Research Program, 26 people will take part in the first phase of the vaccine trials. Stranix-Chibanda said that Zimbabwe had been selected to join the initiative because the country's research environment was conducive to intense clinical trials.
Lasting solution to new infections
Stranix-Chibanda was moved to take part in the project because of the problems HIV has caused in Zimbabwe and the region. "As a paediatrician, I have long worked in Zimbabwe with mothers and babies trying to stop the spread of HIV," she said.
According to Dr Nyaradzo Mgodi, co-principal investigator at the UZ-UCSF, the rate of new HIV infections in Zimbabwe remains alarming. "A vaccine will benefit the population," she said. "We do not have a vaccine for HIV like we do for polio or measles. Due to human nature and behavioural changes, other preventive measures cannot be fully relied on. But a vaccine would be a stop-gap measure against new HIV infections."
Hunidzarira, the clinical trials coordinator, agreed. She noted that, due to poor logistical support in sub-Saharan Africa, only eight male condoms were available each year for each sexually active person.
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