Science Question- T Cell Immunity and PCR Test

[Mummabeary]

Just wondering if anyone can answer this question for me. There have been some good news articles today about T-Cell immunity seeming to protect against Covid even when antibodies aren't present or have worn off from a previous infection.

www.bbc.co.uk/news/health-54781496

The question that I'm wondering is, if you become infected a 2nd/3rd/4th time and your TCell (or antibody) immunity kicks in such that you have no/very mild symptoms and you're presumably not infectious would you still show up as testing positive on a PCR test if you were to be tested in that window? If you were tested in that time where you've been exposed to the virus but your immune system is mounting the response?

I suppose I'm thinking that if that were the case then case numbers would continue to be high long after some population immunity has kicked in (not saying that's the situation now but if we were to continue PCR testing in the future in the numbers we are now).

I think you're right OP, though I'm no expert either.

The threat of lockdowns ends when lots of people aren't going to hospital with Covid any more. Not when we find zero cases, but when we see (close enough to) zero hospital inpatients.

Thanks @ragged. I do agree with you that hospital admissions is the important measure. It's just I wonder whether the mass testing they are doing now (in Slovakia I think & maybe Liverpool) is going to give a distorted picture of the pandemic and increasingly so over time. That's not to mention the downsides of people having to self isolate because they've tested positive even though they've already had the virus and aren't infectious. If this is indeed a limitation in testing it should be made much more clear. Or am I misunderstanding?