Well, let's just talk about Heathrow and not the world just yet. England is a sovereign nation and decides things like testing through its National Health Service. National policy would determine both the airport and airlines testing requirements, and maybe funding. An airport might use 10s of millions of tests a year, but a nation would use hundreds of millions of tests a year.

If you follow British newspapers, they are calling for massive testing because of a second surge of Covid that's started. The government is under huge pressure to do something, but has been silent on plans.

Mr. Kim Thonger, founder of Triedandtested.tech has been quoted saying testing could start in airports by the end of the month. Decide for yourself.

On such a scale, any test would need to be fast, accurate, easy to administer, easy to process, low cost, and easily scalable. Kim Thonger says the antigen test takes only 20 minutes to a result and is rated at 98.98 out of 100 on the scale that's commonly used. Speed and accuracy. As I said, there are many factors in a nation choosing tests, so do your due diligence.