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

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.