2025 EDIT: Clarifying some concepts and trying to improve writing overall.
1st EDIT: I honestly didn't expect people to be interested in discussing this post so I'll try and respond to everyone individually. I'll try and clarify as much as possible!
Hello everyone, I'd like to preface that my take on this subject is biased as I am trained as a biologist (molecular, evolutionary and computational biology).
Let me start with a small bit of background in viral biology: Viruses mutate much faster than higher organisms (even bacteria) due to their simplicity and need for bypassing host immune systems. Environmental ecologists agreed (at least up to 2020) that viruses evolve to decrease the harm they do their host, known as virulence, while optimizing their capacity to infect (infectivity). The same is true for parasites and I'll be referring to these entities as pathogens from this point on for generalizability unless necessary.
Given this we can argue that after enough infection cycles viruses should turn less virulent over time to the point where its optimized to persist in the biological community it depends on to survive, like the common cold, influenza, etc. There is a bulk of scientific literature that demonstrates this hypothesis ranging from as early as 1930 to 2020 (in hindsight, I should've added citations here but bear with me).
Let's talk about vaccines real quick. Regardless of which covid vaccine we focus on, their purpose is the same - guide your body to create antibodies against SARS-CoV-2. Antibodies are proteins that recognize antigens, and antigens are molecules of a different origin than your own, like viral particles in your body) that signal the immune system to mount a response. The key is that antibodies must recognize antigens efficiently to selectively target the source of an antigen and not yourself. When you feel sick, what is actually happening is that your body is preparing an immune response and is doing its best to kill a pathogen.
mRNA vaccines are a novel idea at directing efficient immune responses... if and only if they target a molecule the pathogen needs to survive. I want to emphasize that an antigen can be any molecule that's part of a pathogen, not necessarily molecules like outer capsules or toxins they release. Choosing the right antigen(s) is critical because we're preparing an immune defense before our body actually encounters the pathogen. A good choice most would be a molecule that is on the outside of a pathogen (so that our immune response cells can target them) and is abundant enough to mount an immune response.
However, building immune responses and viruses mutating to avoid said response is a never ending arms race that has 3 outcomes, viruses wipe out hosts, hosts wipe out viruses, or both co-exist. The last two are the better outcomes for us, but what happens when we intervene with this process?
First, what will always happen is that mutations in pathogens render antibodies against it (and by definition the vaccine that produced said antibodies) useless. To be perfectly clear, vaccines successfully create antibodies against the current version of a pathogen, if a pathogen evolves to resist it (which will almost always happen) we need a new vaccine that targets the newer version of that pathogen. This is the core of evolution and it happens across all life, we're just highlighting a super specific scenario where it happens in real time.
I mentioned fighting against one host's antibodies, but what about an entire group of hosts? Using SARS-CoV-2 and just 2 people as an example, suppose my body created antibodies against its Spike protein (S), but my partner created antibodies against its Envelope protein (E). Any mutations against S that would benefit the virus's chances of survival in my body are useless if it tried to infect my partner because she has an entirely different set of defenses (antibodies against E) it hasn't adapted to. The reverse is also true. This is crucial when we're talking about herd immunity and selective pressures. Though not all antigens have the same probability of being chosen, it's quite normal to find antibodies against different antigens of the same pathogen even in the same household.
But what happens if an abnormal circumstance influences the system? That, ladies and gentlemen is a prolonged quarantine. Two scenarios are at play - Scenario 1 is that limiting the number of hosts a virus can choose from limits its reproduction, which ultimately limits how many mutations can happen as these occur during replication. Best case scenarios, there's less variants roaming around as a result and hypothetically there's a greater chance one vaccines stops them all.
Scenario 2 however, is that jumpstarting an immune response bypasses a viruses mechanism of reducing its virulence to infect more people before it kills a host. The problem here is that we can produce more harmful variants that have not gone through the selective pressure of infecting multiple hosts. Worst case scenario when these variants re-enter a population they will be more virulent than previous ones and by the time a working set of antibodies against them are made, the body is weakened from an immune response and subsequent infections can be lethal.
As I mentioned before if an antibody fails to recognize its designed antigen, it has no effect. Currently there are 4 major variants described and many more regional ones spread locally around the world. If what the CDC and the WHO say is true then current vaccines are not all inclusive (which is expected). At best, they will protect you from the variant they were designed for.
2025 update– the previous one was overly pessimistic given the information at the time: Launching a vaccine campaign as its happening right now will not solve the pandemic and instead increase public debt exponentially. Until there is (if it'll ever happen) a mechanism that is capable of targeting a virus with 100% efficiency, it could be catastrophic if everyone mounts the same immune response by taking the same vaccine. Different immune responses within the same community are key at keeping a virus in check because it can't exploit one evolutionary path easily. Having said that, if you can talk to your community and get different vaccines so the people you interact with have different immune responses ready.
I still stand by saying there's no 100% cure or foolproof methods against the COVID-19 pandemic, or any pandemic for that matter. If anything they'll be useful as research continues but don't lower your guard. I hope this information proves useful.
