From what I've picked up separate waves describe what is happening in typical Covid-19 patients: immune reactions that are good enough against the virus in the

From what I've picked up separate waves describe what is happening in typical Covid-19 patients: immune reactions that are good enough against the virus in the throat are insufficient to defeat it elsewhere so you get a first wave in the throat and if the virus spread into the lungs before that wave is over there's a second wave in the lungs. That wave then requires a different or stronger immune reaction.