time now for your questions about the coronavirus here is our science correspondent dirk williams. can we achieve her demeanor see if you can get me in fact it. there are plenty of questions about this pandemic where we still don't have really clear cut answers like when your immune memory of the virus wanes so much that you could catch it again that's happened to a few people but as far as we can tell not really very many so far and number of studies now indicate that at least in most of us the average amused response to sars cove 2 remains active for for at least 6 months which is positive because the average duration of immunity in individuals either after they've had copd 19 or have received a vaccine against it that will play a defining role and health fast we reach her to munity however even if we do begin seeing greater numbers of re infections relatively soon it would make herd immunity impossible to achieve just harder because it's going to take years though to pin down the average duration of immunity i'm discussing it now means that you have to make some assumptions if w