THE ever-changing genetic makeup and rapid mutation of the HIV virus has to a larger extent slowed down progress towards successfully developing an effective HIV vaccine, a top Zimbabwean expert has said.
By Michael Gwarisa
The revelations also follow the recent abandonment of the Imbokodo HIV vaccine or HVTN 705/HPX2008 efficacy studies after revelations that the vaccine was not granting enough protection against infection.
In an interview with HealthTimes, Dr Portia Hunidzarira, the Principal Researcher for the Imbokodo vaccine studies said the HIV virus mutates at a faster rate and because of that, it is always a step ahead and finding a vaccine that can match the speed at which the virus changes is challenging.
There are two different types of HIV. These are HIV-1 and HIV-2. Throughout the world, most people living with HIV have HIV-1. HIV-2 is most common in western Africa. HIV-2 progresses more slowly than HIV-1,” said Dr Hunidzarira.
She added that the HIV-1 viruses are very diverse and there are four groups of HIV-1. One group, Group M, causes most HIV-1 cases around the world.
“Viruses in Group M are further divided into nine subtypes, which can be made up of numerous variants, or strains. The dominant HIV subtype in the Americas, Western Europe and Australasia is subtype B. In Africa, the common subtype is C.
“Your genetics and my genetics differ by about 0.1%; the genetics of HIV most likely to be found in the United States and the HIV most likely to be found in Sub-Saharan Africa differ by at least 100x that much. That makes it very challenging to develop an HIV prevention strategy that will work in both places, much less in any number of other places with as much or more difference in circulating HIV strains.”
She added that unlike COVID-19 where people can recover at times without even the need for medication, HIV has multiple strains that are incomparable to what can be seen in HIV.
“When HIV infects an individual’s body, it destroys the body’s defence system. In this case, you have got a virus that is destroying the defence system that’s supposed to actually protect the body. That makes HIV quite a formidable enemy in terms of trying to find a vaccine that’s able to address HIV itself,” she said.
The Imbokodo or HPX2008 study was a Phase 2 study which was meant to try and find an HIV vaccine that could prevent HIV infections in women who are at high risk of getting infected within the Sub-Saharan Africa.
“The study commenced in 2017 and vaccinations were concluded June 30, 2020 and the major findings of the study showed that the vaccine itself had a favourable safety profile to mean that it was safe and it caused no harm to the participants. However, the vaccine that was tested in this study was unable to provide sufficient protection to prevent HIV infection so the study could not proceed.
“In terms of the challenges that we faced in terms of implementing the study include getting the community to understand about HIV vaccines in general. The communities are aware about vaccines because we know about childhood vaccines but people were not convincible about HIV vaccines and myths and misconceptions also played a part,” added Dr Hunidzarira.