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Study: Certain Vaccines Could Make Diseases More Deadly
sciencehabit writes: New research suggests that vaccines that don't make their hosts totally immune to a disease and incapable of spreading it to others might have a serious downside. According to a controversial study by Professor Andrew Read these so-called "imperfect" or "leaky" vaccines could sometimes teach pathogens to become more dangerous. Sciencemag reports: "The study is controversial. It was done in chickens, and some scientists say it has little relevance for human vaccination; they worry it will reinforce doubts about the merits or safety of vaccines. It shouldn't, says lead author Andrew Read, a biologist at Pennsylvania State University, University Park: The study provides no support whatsoever for the antivaccine movement. But it does suggest that some vaccines may have to be monitored more closely, he argues, or supported with extra measures to prevent unintended consequences."
The idea is that if you vaccinate people but they still get the disease and don't get it as badly, they might not die as quickly, or might not die.
So if they get sick but don't die, the disease has longer to spread.
So I suppose if you're an Anti-vaxxer it's a great argument for why only you should get vaccinated for highly virulent diseases, but you should just let everyone else die faster.
Pathogens don't "learn". They evolve, ok. They adapt, ok. But they aren't sentient. They are not thinking. And especially they aren't thinking "hey, if they vaccinate, they won't die anyway, at least not as fast, so let's get more deadly!" This isn't the fucking Pandemic flash game for crying out loud!
There is no interest of killing a host for a parasite. It's an side effect. Unintended, and actually harmful for the parasite in the long run. Just like poisoning the seas is harmful for us. We ain't some comic book villain who does it for ... well, for being evil. We do it 'cause it cuts costs. The oil spill is only the side effect, not the reason we do it.
So yes, they COULD get more deadly because we don't die as fast and a more deadly mutated strain would kill itself off with the host if there was no vaccination. But that is hardly an argument against vaccination. It only means that at worst we're with vaccination where we are now without. AT WORST. If, and only if, the pathogens mutate in such a way that they get more deadly. Which is neither in their interest nor anything they would (evolutionary) strive for.
What's the benefit for a pathogen to be more deadly? Killing the host is actually bad for it, since that ends spreading (with this host at least).
We used to have a Bill of Rights. Now, with the rights gone, all we have left is the bill.
...they worry it will reinforce doubts about the merits or safety of vaccines...
This attitude about let's not discuss any possible downside because it will give the anti-vax people ammunition is part of the problem. Often forgotten is that a certain percentage of people who get vaccines die. That's an extreme form of take one for the team. At least some of these deaths could probably be prevented but rather than examine that more seriously we get polarized into vaccines are always good with no room for an opposing view. Any opposing views must be the opposite end of the spectrum and must be 100% against vaccines. While vaccines have been outstanding public policy in general that doesn't mean that it couldn't be improved upon. As long as people die from vaccinations there is room for improvement. The fact that we don't seem to be looking into how to lower that number is a problem.
Only if you think Chickens and Humans share enough commonality in our immune systems and the viruses that infect us will act the same in a human host as in a chicken.
If humans and chickens didn't share the biological basis for virus and antibody action, then testing vaccines on chickens would be a waste of time. As animals that evolved on planet Earth, we both have the same mechanisms for mutations, virus replication, and antibody systems, even if the biology isn't identical and not every virus that will infect a chicken will have the same effect on a human. If humans and chickens do NOT share enough commonality, then why do they call it "chicken pox"?
It's ridiculous to claim that an issue observed in testing a virus on chickens cannot apply to human viruses and their immune systems because one is a chicken and one is not.
Yup to what you said.
I truncated my earlier post because I got a call from downstairs that salad, baked chicken, yellow rice was on the table, and strawberries had been cut up for the home made ice cream in the freezer. I believe my priorities are in order.
Reading the study makes it clear that what is happening with these chickens is important to the poultry industry, it's not just a what-if study, it's a "this has happened and we need to find out why" kind of thing.
Anyway, for the benefit of readers who may not have time to read the actual study, in the study, the author mentions what we said, that the increased virulence example that he had discovered for this virus, Marek's virus, had not been seen in human hosts for human diseases.
From the article:
"The imperfect-vaccine hypothesis attracted controversy [11–14], not least because human vaccines have apparently not caused an increase in the virulence of their target pathogens"
Furthermore, the author says:
"Our data do not demonstrate that vaccination was responsible for the evolution of hyperpathogenic strains of MDV, and we may never know for sure why they evolved in the first place. Clearly, many potentially relevant ecological pressures on virulence have changed with the intensification of the poultry industry."
The study also discusses similar phenomena that occurred naturally when exposed survivors in the wild harbored an increasedly virulent pathogen due to their acquired partial immunity after exposure.
What I think is interesting is that the increased virulence of Marbek's is only found relative to unvaccinated chickens. The vaccinated chickens do not experience the increased virulence.
If there is a lesson in this for human vaccines, it is that when we vaccinate, we need to vaccinate as much of the population as is possible, and that you really do not want to be the unvaccinated ones if an analogue does appear in the human population.
Anyway, this actual study is interesting, and I don't see any problems with the way it was executed or written. As is so often the case, the problem comes from people extrapolating from a study things that are not found in the study.
I'm impressed that slashdot can push out this clickbait Monday evening, and that less than 64 people dispute that vaccines suck (excepting those who responded: trolls.)
"The ability to delude yourself may be an important survival tool" - Jane Wagner -