A recently published article gives some insights into the Covid vaxxed still are having numerous episodes of Covid. It seems that the vaccinated do not acquire the full spectrum of immunity of the unvaxxed through natural immunity. The simple explanation is that the vaccine in the mRNA vaccine only acquire immunity to the spike protein, which is toxic in itself. This immunity fades after a few months. However, natural immunity is more robust, and involves a more holistic immune response to the entire virus. Having more bits to go on, immunity lasts longer.
https://igorchudov.substack.com/p/moderna-knew-vaccinated-people-will?s=r