Interesting. For those are curious on why the antibodies might not be effective, can read this:

Having the antibodies against HIV doesn't equal having immunity against HIV due to the structures of the HIV.

HIV infected patient usually produces antibodies against the virus however the antibodies produced by the immune system aren’t effective against HIV. Protein spikes on HIV’s surface are too few and far between for antibodies to adequately latch on to.

Antibodies are tiny Y-shaped protein chains that are produced by the B cells and that latch on to protein receptors studding viruses and bacteria. Not only do these antibodies have the ability to neutralize the invader or flag it for elimination by cells of the immune system, but they also help prevent the virus or bacteria from latching on to healthy cells in the body.

Antibodies are Y-shaped for a reason, molecular biologists suggest: It allows each arm of the Y to bind with more than one protein spike on the surface of a disease-causing microorganism. By binding with two arms, rather than one, a single antibody is all the more powerful.

One of the hallmarks of HIV disease—and a major obstacle to vaccine research—is that HIV antibodies don’t work very well in controlling the virus. Past research suggested that HIV’s receptor spikes are coated with a thick sugary substance that antibodies cannot penetrate. The Y-shaped antibodies don’t have the reach necessary to cover receptors that are spread out across HIV’s surface. In turn, the virus escapes being neutralized and is able to go on and infect CD4 cells in the body.

HIV typically has only about 15 receptor spikes on its surface, and that these are spread too far apart to be targeted by a single Y-shaped antibody. They compared HIV to a similarly sized flu virus, which typically has 450 receptor spikes within much closer proximity to each other hence increasing the effectiveness of the antibodies against flu viruses.

https://www.sciencedaily.com/releases/2010/11/101118123847.htm#:~:text=Researchers%20have%20been%20stymied%20for,be%20ineffective%20in%20blocking%20infection.

The second reason is the the greatest challenge in developing an effective HIV vaccine has been the high rate of mutation and recombination during viral replication . The enormous genetic diversity of HIV is mainly driven by the high rate of variability of the viral envelope (Env) glycoprotein, which ironically happens to be the main target of neutralizing antibodies . The HIV genome contains nine genes which encode 16 proteins including the major structural proteins Gag, Pol, and Env; accessory proteins Nef, Vif, Vpu, and Vpr; and regulatory proteins Tat and Rev. HIV diversity, which is mainly generated by the error prone viral reverse transcriptase, has various implications for disease progression and responses to ART . The high mutation rates of approximately 1–10 mutations per genome per replication cycle, extensive conformational adaptability, and massive glycan shielding of the Env enable the virus to evade the effects of neutralizing antibodies and other immune responses

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7655734/#:~:text=The%20HIV%20vaccine%20can%20either,during%20viral%20replication%20(9).

Edit: links

I also think the vaccine is still in the early stages of testing and more research is needed to determine its effectiveness in a larger population.

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