This is the theory by which allergy immuno-therapy (i.e. "allergy shots") work. You take something that is generating an immune response (pollen, pet hair, foods, etc), you isolate what you think the immune system is reacting to (almost always a protein) and you give the patient periodic injections of it. Eventually the immune system starts to ignore it.
There are really three types of vaccines:
1.) Vaccines that confer long term immunity lasting anywhere from a decade or so to a lifetime. Examples: Mumps, Polio, Smallpox vaccines
2.) Vaccines that confer limited immunity lasting a year or less, but the virus at issue is seasonal and changes from year to year. Examples: Seasonal flu vaccines
3.) Vaccines that confer limited immunity lasting a year or less where the virus at issue is persistent and isn't going away. Example: Covid-19 vaccine
Yes, these are the 3 scenarios, but I don't think there are 3 types of vaccines as such; rather there are 3 types of pathogens that fit this 3-part schema.
(1) With most pathogens, vaccines will confer long term immunity lasting for decades, as you say.
(2) Then in the case of rapidly mutating pathogens like influenza, yearly vaccinations are required to cover the next strain of the flu. It's not that the previous year's flu vaccine has stopped working; it's because the flu virus has mutated, so that it is now effectively a different virus.
(3) As for your third category, what most people on this forum don't appreciate is that coronavirus is an unusual virus, which does not create long term immunity, even during natural infection. This is one of the reasons why you don't develop immunity to the common cold, as many cold viruses are coronaviruses. Most other viruses will produce long term immunity from a natural infection, but coronavirus does not.
This was known right at the beginning of the coronavirus pandemic, that this lasting immunity problem would be a major issue, and would have two very negative consequences:
- People would get reinfected with COVID even if they previously caught it, because natural immunity to coronavirus does not last.
- The COVID vaccines would also likely not be able to create long term immunity.
This is why the idea of getting herd immunity by just letting COVID rip through society was discounted — because you cannot get herd immunity to coronavirus.
If this pandemic had been caused by another virus, like poliovirus for example, then natural infection with that will lead to lifetime immunity. And a single vaccine shot would protect you for decades. But neither is the case with coronavirus.
People on this forum are blaming the COVID vaccines for their poor performance, because unlike other vaccines, they are not able to protect people for decades. But it would be better to learn a bit about the science of coronavirus immunity, so that you can appreciate what the vaccine makers are up against.
As I understand it, this shortcoming is nothing to do with the COVID vaccine technology itself, and is everything to do with the fact that coronavirus itself is a weird virus that does not generate lasting immunity.
If you would like to read more about why coronavirus does not result in lasting immunity, this article from 2017 covers some of it:
Why Don’t We Ever Develop Immunity Against the Common Cold?
This article explains that the spike protein of common cold coronaviruses is made up of three parts, which work to evade antibody attacks from the immune system. These spike protein dynamics relate to how coronavirus infection does not lead to long term immunity. I don't really understand the mechanism, but wish we could discuss fascinating scientific issues like this, rather than politics, conspiracy theory and always taking a negative cynical perspective on the efforts of science.
Edited by Hip, 21 January 2023 - 01:34 AM.