Speed versus accuracy. It’s a trade-off in so many areas of human endeavour, and increasingly it is becoming a crucial factor in efforts to test and trace coronavirus.
The UK has gone for accuracy - tests in which swab-samples are sent to laboratories for molecular testing, giving a highly accurate result which can also tell doctors how muchof the virus is in a patient’s system.
The downside, of course, has been delays in getting samples to the lab, a laboratory system so overwhelmed that many of those samples then get send abroad, and more than half of all results not being delivered within three days. Sometimes much longer.
The Italians have gone a different route, using a test originally developed in South Korea that delivers results in less than 30 minutes.
Slightly less accurate, with no information on viral load, but with a while-you-wait machine readout that is saving people many days of worry and self-isolation.
The new system is one of the first things you see on arrival - large blue signs greet you atRome’s Leonardo da Vinci airport, funnelling anyone arriving from a high-risk country into a Covid test centre.
It takes barely more time than collecting bags from the carousel.
Anyone who tests positive is immediately isolated and given a full laboratory test, those negative can head home.
They know that it may very occasionally mean that an infected person tests negative and then goes out into the community, but have decided that is a smaller risk than the British policy of demanding all travellers put themselves into quarantine for two weeks, with few checks that they are really doing so.
The hope is that the system can soon be expanded to test all travellers not on arrival butbefore they get on a plane, giving huge reassurance to people about the safety of air travel.
The airlines and travel industry as a whole are desperate for this to happen.
But this all goes further than just air travel. Anyone who fears they may have been incontact with the virus can get a prescription from their GP for a rapid (and free) test.
At a drive through centre a nurse will administer a swab test and produce an almost immediate result.
There are queues, but they are not very long, and considerable customer satisfaction that lives can get quickly back to normal.
There is another huge advantage, if someone tests positive, their contacts can be traced,contacted and tested within days.
If you wait days for a test, and days more for the result, tracing those you came into contact with becomes harder, and in all that time people potentially exposed will have been moving freely in the community.
The Italian authorities are happy to be judged on results - from having had the worstrecord in Europe, they now boast one of the best.
The daily figures for new cases are running at about half those in the UK, and much better than either France or Spain.
They give considerable credit for that to a test and trace system that, rather than being mired in controversy and recrimination, is giving quick results and earning considerable public confidence.