Достаточно ли вакцин в борьбе против ВИЧ?
We know how to stop the HIV/AIDS pandemic.
Everybody just has to follow a few simple rules: don't have unprotected sex, don't share needles, get tested for HIV, arrange universal access to anti-HIV medications, and take them properly when they're prescribed.
There are probably a couple of others, but you get the point: If we all did all the things we know how to do, we could interrupt HIV transmission, prevent new cases of AIDS, and over time stop the pandemic.
So problem solved, yes?
No, according to Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases and his NIAID colleague Hilary Marston, MD.
In a Perspective article in the Feb. 6 issue of the New England Journal of Medicine, they argue that stopping the pandemic will also need at least one other intervention -- a vaccine.
Frankly, the piece came out of left field for me. I didn't think there was even a question about the need for a vaccine and, indeed, experts I asked said a vaccine will be a key piece of the puzzle.
Fauci, when I asked him, said the point needs emphasis.
"There is among some quarters," he told me, "the feeling that ultimately if we just pushed hard enough with implementation of existing interventions that we will in fact see the end of the HIV/AIDS pandemic."
It's true, he said, that in some places the tide is turning, with fewer new infections than people started on therapy. And one reason for that is the success of a range of advances over the past few decades -- male circumcision cuts the risk of HIV, antiretroviral treatment cuts the risk of HIV, consistent condom use cuts the risk of HIV, and so on.
But such success always holds the seeds of failure.
Let's face it, most of us can't keep to an exercise regimen for more than a month after New Year's. How can we expect that every human being on the planet -- or even just those at high risk of HIV -- will always follow those simple rules I mentioned off the top?
Even when HIV is a clear and present danger, people forget to take medications or fail to use condoms. How consistent and committed would we be if we were told we were living in an AIDS-free world?
Fauci and Marston cite Zanzibar, where in the '50s and '60s a program of indoor spraying dramatically cut the prevalence of malaria parasites. "People thought it was over," he told me, so the spraying program lost its funding and, predictably, the parasites roared back.
All of the very successful prevention methods we know of have the same drawback -- you have to keep doing them even when the risks seem small and if you stop, boom! You're back in trouble.
"That's my concern," Fauci said. "Human nature has a bad track record." So, he and Marston argue, a sustained end to the pandemic will need something that reduces the human factor -- a vaccine.
After all, human nature may have a bad track record, but science has a pretty good one.
Still, an HIV vaccine? It's a litany of failure. The most impressive result so far -- in more than 30 years of trying -- has been an experimental vaccine that is 31% effective. (If you look at the error bars, it might actually have almost no efficacy.)
Well, yeah. But in the other part of the New England Journal piece, Fauci said that there is reason to believe that all those failures might have paved the way to a success.
There remain "significant scientific challenges," Fauci told me, but the so-called B-cell lineage approach holds enormous promise.
Briefly, the goal is to find a way to generate broadly neutralizing antibodies to HIV. Such antibodies are the usual response to most other viruses, but HIV is an exception in most cases.
But it does happen over time in some infected people -- as B cells and HIV co-evolve, their immune systems generate antibodies that bind to HIV with greater and greater affinity.
The trouble is that the virus is firmly entrenched by the time the broadly neutralizing antibodies evolve.
Recent advances in the understanding of the process hold out hope that it might be something that could be kick-started artificially without HIV infection.
Indeed, work in the field has been "catalytic," according to Myron Cohen, MD, of the University of North Carolina Chapel Hill. He told me by email that work on various approaches is moving rapidly and is so fundamental it could "change the way we think about vaccine development" in general.
"The scientific tools and creativity employed toward development of an HIV vaccine designed to generate broad neutralizing antibodies has been breathtaking," Cohen said.
Will that creativity lead to a vaccine? I think the answer is Yes, sooner or later. Sooner would be better, of course, but in the meantime, we really do know how to slow down the pandemic.
We just have to do it.