Is there any reason to think the immunity would last? Like is there evidence in animals? Because the one mRNA vaccine we gave had in people did not provide much immunity past three months. That was in environment of virus mutating, but so will the flu.
Vaccines generally work enough differently from the disease that even if immunity from an infection would fade after 90 days, the vaccine can still work for years.
No, they never did. Influenza is a family of viruses that mutates extraordinarily fast. Last year's flu vaccine isn't useless because your immune system already forgot how to make the antibodies, but because there are new flu viruses every year.
The RNA vaccines at least specifically target the part of the Covid virus that makes it special compared to other coronaviruses. If that part mutates in a way that invalidates the protection caused by the vaccine, it almost certainly renders the virus harmless anyway.
Even if the protection does expire, there is no reason to believe it happens at flu-like timescales. Of course if by (is that the right preposition btw?) "constant refreshing" you mean every decade or so, that is possible.
What do you mean flu immunity only lasts 6mo? As I understand it, flu vaccines are done yearly due to mutations rendering the vaccine impotent for the next strain. However, it seems like you're implying that the vaccine "wears off" or something.
And to be useful they would have to be infected over the time the vaccine is effective to build longer-lasting immunity instead of losing the vaccine effectiveness over time completely, no? (Just a guess, I'm no expert.)
I think it is both. The mRNA vaccine immunity did not wane just because of changes in the virus. That was probably a factor but in this case I don't think it was even the biggest one. The immunity just wanes, even to the same strain. It is to do also with the immune system itself.
I was hearing some doctors saying on the radio that any flu immunity is short lived, this is why we need to have the anti-flu vaccinations every year, that cover the typical/usual strains. If immunization lasted forever there wouldn't be a need for annual vaccination.
Mutation is not the only factor determining how often a vaccine would be given. If antibodies only last a year from the vaccine dose, it should still be given yearly, even if the virus has not mutated.
If prior exposure to the virus itself won't give a person immunity, I would expect it would be much more difficult to create a vaccine to grant immunity. I wonder if the 18 month vaccine timeline I have heard mention would be affected.
Only for a few hours though, not 2 weeks+, and viruses don't mutate on a doorknob. Someone who got vaccine and falls in the ineffective category will likely not die but will be a spreader for a few weeks, with some nonzero probability of mutation, and that times 1/3 of the population that got the vaccine would give the virus a lot of opportunity to mutate.
Why would you expect a vaccine to confer significantly longer lasting immunity than an ordinary infection? What evidence do we have that natural immunity lasts any longer than a year?
They will work fine because this virus can't evolve for shit. It's only produced 2-3 strains and only has one external protein it can mutate. The current vaccines are still good enough against it, and it doesn't take long to edit an mRNA vaccine either.
> I will transmit a virus with a 99.95% survival rate for people under 70.
This math is wrong, you should think of it as getting a flu but ten times worse that also gives you a permanent heart condition. And remember that the flu is already ten times worse than you think it is, because the last thing you thought was a flu was just a cold.
My understanding is that this is more about generating a robust immune response in the first place than about losing protection over time.
There have been a lot of studies looking at third shots, at natural immunity combined with vaccines, and even at mixing vaccines. And the general idea is that there are ways to generate a more optimal immune response, and the vaccine courses given emergency authorization are probably not the best of all options.
Researchers have yet to determine how long natural immunity lasts, and it may last for a very long time. Immunity from vaccines is expected to be at least as durable as natural immunity, though some studies have shown a slight decline in protection over months. But there are definitely no clear signs yet that an annual shot will be necessary.
There are a lot of factors that determine the duration of efficacy of a vaccine. Broadly speaking, you can lump these effects into 1) decaying immune response and 2) mutating disease vectors.
For number 1), what you have to know is that the human immune system is a goofy non-linear Rube Goldberg machine. It's not something that an engineer would come up with. Some vaccines work by promoting an ongoing immune response to certain proteins. You can think of the antibodies as like "wanted" posters, and when a real virus with matching features is detected, it sets off your immune system. But if those proteins are passively introduced, they will decay in your bloodstream over time. Some proteins will hang around longer, others do not, perhaps because it just happens to be structurally similar to some protein that is metabolized by naturally present enzymes. There are also crazy feedback loops that can keep your immune system primed by synthesizing the antibodies from a sort of "memory". Look at the B-cells, they basically pick up any random proteins they think are junk, learn how to synthesize new proteins that stick to it, and then it wears all those proteins around like a hat. And when it's hat sticks to stuff, it tells some other cell to start making lots of party hats for all the other white blood cells to wear so they can sweep up the foreign substances. But these feedback loops are not always stable and can also fade with time. Some antibodies are more stable than others, and some just need a much lower blood concentration to be effective. It's really hard to predict, especially with new diseases.
The best vaccines work by having an actual live virus that lives and replicates inside your body, sometimes for decades. These are your "one-and-done" vaccines, and they're actually really hard to make! You basically have to engineer a virus that lives inside of you, forever, but doesn't hurt you. Instead, it just looks sufficiently similar to a different virus that could hurt you, and it keeps your immune system primed with antibodies to keep the virus in check if you are exposed to it.
Number 2) is the reason we have to get a new flu shot every year. The virus mutates very rapidly and different strains can mix-n-match easily. The Covid virus is already mutating into several variants of concern, and because people are not getting the vaccine which is effective for the strains that are out there now, this will likely become a reason why we have to get regular covid shots.
The upshot of all of this: we had an emergency and needed a vaccine fast. We've come up with two solutions so far: non-replicating adenovirus vaccines (such as AstraZenica, sputnik, etc), and the mRNA ones (Pfizer and Moderna). Both of these work by basically introducing a dead protein into your system, which teaches your immune system how to identify Covid and start attacking it before it can take hold and do damage. But as you can see, it's hard to say how long this can be effective before it needs to be renewed.
Anyone who doesn't like the idea of getting follow-up shots should get to work on making a one-and-done, live, replicating Adenovirus vaccine! But they had better hurry up because if situation 2) takes hold, you're going to need a new shot every year anyways.
Except it was widely reported that natural immunity lasted 3 to 6 months and that the vaccines would last 2 (at least Moderna), and the nuances there I think would be lost on a lay person. I even had an immunologist explain to me in detail why the immunity from the vaccine would be way stronger than acquired immunity. It doesn't really build confidence in science if, while we're finding new things, everyone pretends that the conclusion du jour was always obvious.
It certainly confers immunity for a short period of time. How long that immunity lasts for is unknown, but it’s not unreasonable to start with an assumption of “at least a few months”.
There’s also not strong evidence that there are two sufficiently different strains. Viruses experience small, mostly meaningless, mutations with great frequency. The research talking about S and L types are actually just an arbitrary categorization of many different mutations of the virus.
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