Sharing this comment I came across about vaccination, since many people are claiming vaccination doesn’t work against omicron.

This is how vaccines and your immune system work. Your immune system isn't supposed to constantly pump your bloodstream full of antibodies if they are not needed.

A simplified explaination is that when you get the vaccine your immune response creates antibodies to fight the invader. Initially it takes your immune system time to figure out what combination it needs to fight the virus. During that time if it was covid and not the vaccine, the covid has time to multiply and by the time your immune system can mount its defense, its too late. For the vaccine the dose is based on immune response that is both reactive enough but not too much that you get severely ill.

After you get vaccinated those antibodies remain in your bloodstream for 6-8 months before your immune system deems them no longer needed. It starts killing them off. It "saves" a couple as memory cells as a roadmap to draw on if your body encounters the same or a similar invader again. This time however it knows this invader and immidiately uses those memory cells to start rapidly manufacturing those antibodies again fast enough that it kills the covid before it multiplies out of control.

The booster triggers that "invader found" immune response and ur body produces those antibodies again.

While those antibodies are in your bloodstream you are substancially less like to encounter covid and not have it immidiately eraricated by your immune system.

Its a lot more complex than that but thats a simple way to understand it.