shows that people who have recovered from covid have strong immunity and i mean b-cell data just this week actually and t-cell data, those are called memory cells. antibodies will actually be higher if you've had a severe infection. lower if you've had a mild infection. but they come down after vaccination anyway. it's about what is cellular memory. >> isn't it, dr., gandhi, a very individualized process? in other words, millions have gotten the vaccine and there's a ton of data as to what we can expect in those cases. but for those that have had it, how do we really know, inlay terms, that they're resistant to getting the virus again? is there a way to measure it? >> there's not because, like i said, the antibodies will come down, given your distance from when you've been infected and how severe it was. so, what they're doing in