That is why we have to find a way out of the lockdown: because, as I wrote, you can't confine people to their home for too long. But not because we have "too few sick". If you are playing towards herd immunity: it doesn't look like we are getting there with "acceptable" infection rates. The disease is too nasty for that. So we have to reduce the lockdown in a way so that the infection rate does not increase significantly.