some lean toward the virus is coming from people whose infections are not being captured by sequencing. others suspect it may be coming from virus infected animals. possibly the enormous population of rats. even then the favored theory can change from day to day or hour to hour. what is your reaction to that? it seems kind of concerning, especially given the widely accepted origin theory. >> what we know now is there is so much of this virus that it has gotten into various animal species. one of the reasons we'll have a hard time eradicating this virus. mutations happen. we're picking them up in waste water. whether they represent random mutation that's don't mean much in humans or animals. we'll have to sort that out. >> you often use the analogy that covid spikes are like weather. when cases are high, it's a downpour. when cases are low, it is a drizzle and we can start