Originally published at: HIV vaccine trial begins | Boing Boing
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Fantastic news! A question for those who know more than I do: Is waning effectiveness built in to mRNA vaccines as a class, or is it particular to COVID, I wonder? Can we expect the HIV vaccine response to have about a 6-month effectiveness as well?
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We are living in an age of medical miracles.
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And morons. Conspiracy theory about vaccinated people shedding HIV spikes incoming!
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Well, I’ve barely seen substantial coverage of this on any major news outlet, so it may just follow the course of the last 40 years of US HIV policy and just be completely ignored.
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i would anticipate that the waning effectiveness of the covid vaccines relate to the speed with which the virus mutates, especially because of the enormous numbers of infected individuals. i would expect that retroviruses as a class and hiv specifically would be less prone to such problems.
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I hope that they can pull it off; it’ll be a huge boost for areas of the world where the virus is endemic, like Eswatini and Lesotho.
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If that were the case, though, wouldn’t it be true that the effectiveness against any particular variant would remain constant, and reduced effectiveness would only be against new variants? I was under the impression that there is an overall reduction in effectiveness against COVID over time, having to do with the body’s response, not that of the virus. I could be totally wrong.
How soon before there’s a group that tries intentionally to get HIV as to achieve herd immunity so they don’t need to take no wacky vaccine.
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Yes, this. Covid has mutated quickly and there have been a little under 5 BILLION recorded infections. It is probably higher than that.
We have known about HIV for 40ish years and I don’t recall any major mutation.
Polio and smallpox both are from a virus, with the later being eradicated.
So clearly we can expect different results from different types of viruses.
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I will happily go back to the early 80’s and give them the vaccine.
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What a time to be alive - one of those rare occasions I can say it sincerely and without weary cynicism.
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Its a bit more complex than that. Part of the waning efficacy is the loss of neutralizing antibodies. This is actually a normal function of immunity.
To avoid having to keep neutralizing antibodies around in high concentrations at all times for every infection you have ever seen your body produces what are called memory cells. These then sit around ready to mount a fast response when you are re-exposed to an infection. However this is slower than the response from active neutralizing antibodies that are already present.
Then there are the changes to the virus which your immune system will attempt to adapt to through a process called somatic hypermutation but again this isn’t the same as having ready to go antibodies in circulation at high concentration so variants reduce the efficacy.
The there is the question of how we defined efficacy? We typically define this by picking an endpoint (or goal we are measuring) this can be reduced transmission (needs a fast response) or reductions to symptoms, hospitalization or death. This is really poorly communicated in a lot of the reporting on efficacy. Depending on the infectiousness of the virus, speed of symptom onset the balance of these can be complex. Each infection is a bit different and there are even more factors (tissue specific immunity etc etc.). So for Sar-CoV2 we have a vaccine that is currently very effective at preventing severe illness, but is less effective at preventing transmission and minor symptoms (particularly after 6 months). Boosters are improving the efficacy in mounting a fast immune response, and proving to be very important in people with weaker immune responses (for example seniors) for whom the higher neutralizing antibodies are critical to survival.
So yeah complicated. The vaccines are losing efficacy to some endpoints but holding strong in others.
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Thanks!
Waning immunity seems to be a characteristic of coronaviridae. Since tis was the first mRNA vaccine, I think there is no way with current data to answer the question meaningfully, though. We need an n > 1 to do so, but I can think of no reason that it should be a general characteristic of the tech.
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HIV-1 and HIV-2 are significantly different, enough so that there was discussion at one time (decades ago) of a “second genesis” situation. I think that has receded, but I honestly have not kept up with HIV literature in decades.
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I’m still amazed we have coronovirus vaccines that have evidence of any long term immunity. It’s really remarkable.
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You gave a great answer that touched on a lot of the same things I was going to say. I’ll just add one additional factor that I learned on a medical podcast (and which sounds right to me but feel free to correct if not)
Respiratory viruses like Covid do a lot of their initial viral replication in the nasopharynx, which blood-borne antibodies can have a difficult time reaching as effectively as some other parts of the body, so the virus can sometimes gain some footing ahead of a strong immune response. Viruses that do their replication primarily in the bloodstream (such as HIV) encounter the antibodies (as well as the other parts of the immune system) more quickly and in greater numbers, which gives some hope that a vaccine would potentially maintain effectivity longer. But it’s obviously too early to say for sure.
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There are companies working on a nasal mist vaccine for SARS-CoV2 to attempt to induce a mucosal immune response for this reason. Ideally faster and more accessible to the actual site of infection. It will be interesting to see how they work out.
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The experience with FluMist, the influenza equivalent of what you are discussing, was pretty discouraging. Anywhere from 0-10% protection before it was withdrawn. If they ever figured out where the problem lay, I never heard. Still, it would be great if that could be done.
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