analyst. doctor good evening. does this new guidance from the cdc make any sense to you? >> not really. when something fails the common sense test people are just not going to follow it. i think what the cdc should have said is it is too bad we don't have enough testing but if you happen to have tests then that is a good way to end your isolation. instead this guidance is saying if you test after five days but if it is positive after five days you have to add your isolation to five more days? that is going to disincentivize testing which is not what we should be doing at it point. >> don't people test positive for a while after you contract covid? >> with the pcr test, yes you could test positive even for weeks after. but the antigen test the rapid at home antigen test usually that is a pretty good test for infectivity. are you infectious at this point in time. a lot of people could clear the virus after five or six days.