HIV Vaccines — Fact or Fiction?

Dorothy Crawford’s excellent book Viruses, A Very Short Introduction has an intriguing section about why, 30 years after HIV was first identified, there is still no effective HIV vaccine.

It has not been for lack of effort. Huge amounts of money and scientific effort have been expended.  Crawford outlines three main problems.  First, because HIV mutates at a high rate, there are no, after 30 years, many different varieties of of HIV circulating in the human “herd.”   Second, because the human immune system cannot clear an HIV infection, this tells us that it’s very hard to clear HIV… it’s a high hurdle any vaccine has to exceed.   Third, because HIV transmission is usually via the genital tract, that is where the antibodies and immune T cells that are stimulated by a vaccine must reach.  Lastly, because HIV can transmit inside of cells as well as as a free virus, it greatly complicates the job a vaccine must do.

In sum, it’s a tall order across these four difficulties, and Crawford is not optimistic that a vaccine can be developed.  However, there are effective measures that can be taken to help someone from getting infected.   If an HIV-infected person has a sexual partner who is un-infected, then that partner can be largely protected by giving them antiretroviral drugs.

We don’t want to end on a completely negative note, even though HIV mutates rapidly and has unique ways of evading the immune system, some vaccine trials have shown partial sucess. The RV144 clinical trial in Thailand, reported in 2009, demonstrated a 31% reduction in HIV infection. It’s not ready or enough to deploy beyond testing, but it’s a start.

~~ Robert Carr

Sources:

Crawford, Dorothy H.   VIRUSES, A Very Short Introduction.  Oxford. 2018.

https://www.niaid.nih.gov/sites/default/files/hivvaccineinfographic.pdf