I returned from Australia earlier today, changing planes at LAX. The international terminal and Delta's domestic terminal were no different whatever from any previous trip. That is, there was zero difference from any previous trip.
While waiting in line at the ticket counter in Australia I was asked the same screening questions I've been asked the past 20 years ("who packed your bags..."), but with the additional question of whether I'd been to China, Iran, or Italy in the past two weeks. However, anyone who has paid the least bit of attention to the news would know that answering 'yes' to that question would keep them from boarding the plane so, for protecting the public's health, that question is useless.
During the MERS outbreak I passed an IR camera in the Beijing airport. From the display I could tell they had set the threshold of the camera at ~98.6 oF to make anyone with a fever stand out like a sore thumb. Screening like that is effective, but implementing such measures requires a government that consults experts and then allocates resources to solving the problem rather than to PR. Experts have been calling attention to Covid-19 for two months but, as of today, no IR cameras are set up in the International Arrivals hall of LAX.
I'm not an expert in communicable diseases so I don't know what the best, most effective screening methods would be for Covid-19. However, I do know that asking people to self-report and be banned from travel if they give what any halfway informed person knows is the wrong answer is not an effective screening method.
