Durban — The South African Medical Research Council (SAMRC) said constructing an effective HIV vaccine is necessary even though it has its scientific challenges.
This was revealed at the 2023 11th Aids conference.
The conference started on Tuesday afternoon and will end on Friday.
It is taking place at the Inkosi Albert Luthuli International Convention Centre in Durban under the theme “Act, Connect and End the Epidemic”.
SAMRC president and chief executive Professor Glenda Gray said they had a rich scientific portfolio in approaches but their scientific challenge was to put these different approaches into a coherent vaccine regimen.
She said one needs to prevent acquisition or cure early established disease, a much higher bar than traditional vaccines such as Covid-19. She said the genetic diversity of the virus is greater than any other pathogen.
“Many parts of the HIV trimer create diversionary antibodies and we don’t have a systematic approach to define these and cut them out. There are also many fewer trimers on the surface than most viruses and neutralising antibodies cannot cross-link,” said Gray.
She added that there were no human cures for HIV, hence no immunological models to mimic. However, she said the study of Antibody-Mediated Prevention (AMP) demonstrated that broadly neutralising antibodies are capable of preventing HIV acquisition and provide the future roadmap for vaccine development.
Gray said the study also demonstrated that they need to make Broadly neutralising antibodies (bNAbs) to more than one site. The bNAbs are a type of antibody that can recognise and block the entry of a broad range of different strains of HIV into healthy cells.
“Vaccine approaches need to shift to eliciting antibodies to known conformational structures that elicit such antibodies,” said Gray.
Talking about pre-exposure prophylaxis (PrEP), Professor Sinead Delany-Moretlwe, from the Wits Reproductive Health HIV Institute, said people who used PrEP discontinued after six months. She said when it was introduced 2.2 million people used it around the world.
“After six months, 41% of the people discontinued taking the pill. They were tired of taking it every day – 31% of those people are young females,” she said.
Delany-Moretlwe added that there was a need for a range of options for prevention that can provide a choice and increase HIV prevention coverage across the life course.
“Long-extended delivery products are being introduced to the health system. There is also a range of topical and multi-purpose products in early-stage development,” said Delany-Moretlwe.
She also raised concerns about the costs and accessibility of PrEP. She said prices may limit access despite effectiveness.
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