Vaccines that mimic infections have proved over time to be one of the medical discoveries that have saved countless lives, second only to perhaps antibiotics and surgical anesthesia. But antibiotics can and often are misused, and their misuse leads to promotion of "super strains" of bacteria that can be extremely difficult -- and, on current trajectories, it is projected impossible in the future -- to control.
The common -- and safe -- vaccines given to people all work on the same basic principle: You take a virus, either attenuate it by modifying it so it cannot replicate well in a human cell (often by passing it through other animal cells) or kill it outright and then give it to the person or animal to be protected. The recipient's immune system believes it is being attacked by the original disease and mounts an immune response.
But -- there is no, or only a very weak disease.
What you're left with is the same outcome you'd have from natural infection if you were to survive it in terms of immunity. The immune "memory", in B and T cells, along with antibodies, looks identical -- or very close to identical -- as if you got the actual disease and suffered through it.
Qualifying these vaccines is primarily a process of making sure that they do not revert to their virulent form in the body, a risk that can happen with an attenuated vaccine product. These vaccines produce "sterilizing" immunity in the recipient -- that is, you cannot get the infection again as your immune system will interdict the bug before replication can take place to any material degree, and thus if exposed later you will never have a material viral titer. Without a viral titer you cannot shed anything and thus you also can't give the infection to someone else.
It is this key fact that makes most routine vaccines safe in terms of not potentiating mutations that all viruses undergo. A vaccinated person who has "sterilizing immunity" cannot become part of a chain of replication for a mutated strain that is more-virulent because they are incapable of transmitting the virus to someone else. The exception among the common vaccines used today in the US is polio; the injected form does not produce sterilizing immunity and this is only safe to do in the US because polio has not circulated in the US since the late 1970s. When it was circulating we used a combination of both the shot and the oral attenuated vaccine for this very reason; the oral vaccine occasionally can and does produce polio but it also produces sterilizing immunity. In parts of the world where polio still circulates the oral form is still used for this exact reason.
Coronaviruses, which infect not just humans but also domesticated and food-source animals, generally cannot be vaccinated against in this fashion; neither can HIV and a few other forms of viruses. The reasons are different for each family of viruses where it does not work but all boil down to the virus' characteristics and mutation patterns, along with how your B cells respond. With coronaviruses the problem is that attenuated viral vaccine attempts have repeatedly reverted to the virulent form in the body, usually after a couple of hundred passes through cells on average. In addition these attempts in animals have repeatedly produced ADE instead of protection; in other words, instead of protecting the recipient they make a future infection worse, usually killing the infected animal (in particular this occurred with a candidate for a vaccine against a coronavirus that primarily infects cats.)
That has led to the various "novel" attempts at vaccines developed this time around for Covid-19. This is not the first time we've tried this sort of thing, although it is the first time in humans.
Unfortunately the history of vaccines in the animal world with non-sterilizing immunity has taught us lessons that we apparently have set aside in our haste for a Covid-19 answer. To understand the problem you must understand the natural progression of viruses generally.
It is to the advantage of a virus to spread widely, of course. It's not that a virus has a mind, but rather that the more-widely it spreads without killing the host the more replicants of it there are. It therefore "wins" genetically. A virus that violently attacks a host and disables or kills the host before it is passed to another victim loses; a clearly-diseased human will be shunned by others, and one that is dead cannot interact with anyone else. Thus by pure mathematics viruses as they mutate tend to favor less-virulent but more easily-transmitted mutations; those are more-successful in getting passed on to others before their more-virulent cousin manages to infect the same person and, as the population gains antibodies so long as the immunity has cross-reaction capacity those particular mutations are the ones most-likely to get passed on and the more-virulent ones are selected against.
A vaccine that mimics natural infection does not tamper with this process because from the virus' point of view a person vaccinated is someone already infected. There is no difference in regard to how the virus behaves when it encounters someone who was either previously sick or vaccinated with such a formulation.
This is not true for vaccines that do not produce sterilizing immunity or worse, do not mimic natural infections at all.
Specifically it is very possible for such a vaccine to actually make it more-likely that a deadlier form of the virus will survive and in fact thrive! If the vaccine prevents you from getting seriously ill or dying but not from developing a viral titer and being able to pass the infection to others then it erases the natural disadvantage that mutations making a virus more deadly would otherwise have.
That raises the risk of stopping or even reversing the natural mutation processes by which easily-communicable viruses decrease in their capacity to kill people.
Take SARS. SARS died out quite quickly because you were not able to effectively transmit it until you were quite ill to the point that anyone who saw you would have good cause to think you were sick and it killed a large percentage of those infected. Thus it very frequently failed to find a new host; general human revulsion to people who are violently ill, once word got out that "it might be SARS" kept a person afflicted from effectively giving it to others, and as a result the virus killed itself off by failing to propagate in a very short period of time.
Now consider a vaccine that makes SARS a low-level cold nuisance or a "silent" infection but does not produce sterilizing immunity. A widely-vaccinated population would spread SARS like wildfire through the world and anyone unable to be vaccinated, who had their immunity wear off or who was not vaccinated would get it and DIE.
Such a vaccine would take the few thousand deaths from SARS and turn it into tens of millions or even hundreds of millions of deaths, selecting with vicious efficiency for extermination the elderly who poorly responded to a vaccine or were unable to take it due to serious illness where the vaccine might kill them outright, those with cancer, people with autoimmune diseases who could not be vaccinated, those who couldn't afford vaccination and those who either decided not to take the shot or who's immunity wore off.
Is this a realistic risk from the Covid-19 vaccines?
YES, and if it happens there will be exactly nothing we can do about it.
Remember that the CDC and other "authorities" are telling you point-blank that they do not believe these vaccines produce sterilizing immunity. That is, you cannot take off your mask, stop distancing and resume your normal life after being vaccinated. Why not? There is only one reasonable explanation: They do not believe the vaccines prevent you from being infected and producing a titer of virus sufficient to infect others -- the vaccines only decrease the rate of severe disease and death.
Such "vaccines" must NEVER be given on a widespread basis to the public when a particular virus is circulating in the population as doing so risks a catastrophic mutation cascade that will kill tens or even hundreds of millions of people. While numerically the risk of this occurring is likely quite small the consequence if it does happen is catastrophic and thus that course of action should never be undertaken. A vaccine that behaves this way is simply never safe in the general population; the only rational use is in very high-risk individuals who make up a too-small and non-concentrated portion of the population to form a disease chain vector for a more-virulent mutation.
Today Covid-19 is not a very virulent virus, despite all the screaming Karens. If infects easily but only kills, statistically, those who are seriously morbid in the first place. The primary factor is not age contrary to people's assertions -- the NYC Coroner data makes this crystal clear but the media and our so-called "experts" are knowingly lying even with nearly a year's worth of said data now under our belts. Simply put if you are not severely-morbid the odds of Covid-19 killing you are about 3/100,000 irrespective of age if you get infected -- that is, 0.003%. Or, if you prefer, 99.997% of the time you will survive.
The risk is not age-specific; you can literally count on your fingers the number of people over 75 who do not have one of the listed conditions that Covid-19 has killed in NYC.
This is a very mild disease in those who are not morbid -- in fact it is materially less dangerous than the flu which more-frequently kills young people with no particular morbidity. That doesn't mean it can't kill someone without one or more known risk factors -- it most-certainly can and occasionally does, just as Chicken Pox did occasionally kill a child who got it. But unless you have one of a particular list of morbid conditions you accept far more risk of death by using a passenger car, either as a driver or passenger, over a period of about six months.
Now if you do have one or more of those conditions you're at materially higher risk.
But even so -- perspective is important. We have learned how to treat this disease and in many cases how to prevent it from transmitting from one person to another using prophylaxis, not vaccines. If you are one of the people who is not going to get seriously hurt or killed from a public health perspective your infection is beneficial to the community as a whole.
The question of whether your vaccination is likewise beneficial is not known. We cannot say that it is identically beneficial as an infection because these vaccines are not mimicking natural infections; they intentionally target only part of the viral structure because attenuated vaccines are known to be unsafe with coronaviruses in that they revert and wind up causing disease -- so to avoid that they intentionally didn't use the entire virus. Instead they "engineered" an injection that causes your body to produce the spike (and only the spike) and then your immune system produces antibodies to that.
But -- this means we do not know if you can get infected and emit the virus toward others after being vaccinated. We did not study it in the lab because challenge studies are generally not ethically permissible in humans, we did not do the animal trials and there has been insufficient data from infections and monitoring the population yet here we are jabbing people willy-nilly without knowing this critical fact.
These vaccines should have never been put into widespread use until and unless we knew if they produced sterilizing immunity as that should always be a gating requirement for widespread use of any vaccine. By using them widely, if they do not produce sterilizing immunity, we take the very real risk of promulgating a much more-lethal strain of Covid-19 that would otherwise fail to find traction statistically and thus harm very few before it is outcompeted instead spreading it worldwide, and for those who have had their immunity wane, who cannot be vaccinated due to immune or medical compromise (e.g. anyone undergoing cancer treatment which damages the immune system) or otherwise that strain will result in a massive amount of mortality.
This is not conjecture folks -- it has happened in animal husbandry and has resulted in avian flu potentiation wildly beyond what used to be the case. Avian flu strains used to kill a fair number of birds who contracted it but now, as a result of vaccines that do not present sterilizing immunity it is now nearly universally fatal among poultry. If such is detected in a flock today the usual response is immediate culling of the entire population at that location because it is nearly-certain to be fatal to the infected birds anyway and if it gets out of that facility and into another one it will kill all the birds there too.
The nightmare scenario is one in which the virus mutates in this fashion and in the process evades the vaccines as well in which case you now have not a 3/100,000 risk of dying but a 1/100 or even 10/100 risk with no effective means to stop it at all.
The odds are relatively low that this will occur will but the path for it to happen has been deliberately opened up by distributing vaccines on a widespread basis, not just to those at the highest risk (e.g. nursing home patients) without first proving up that they do produce sterilizing immunity and refusing to approve those that do not.
This was and is stupid and if we lose the bet there will be literally nothing we can do about it other than suck it up and watch the worldwide population get nailed to whatever degree occurs.