How to build and deploy testing systems at unprecedented scale – from today’s Economist magazine.

Countries will have to do it to end their lockdowns safely

---

SARS-CoV-2, the virus that causes covid-19, is an unobtrusive piece of biological machinery. It spreads parasitically through the respiratory tracts of human beings, often without provoking symptoms in those who carry it. Yet for some, particularly the old, it is deadly. This combination of properties make the pandemic both dangerous and difficult to stop. As of April 22nd it had killed 182,000 people.

So far, every country that has reduced covid-19 infection to low levels has relied to some degree on “social distancing”—that is, either encouraging or forcing people to stay at home, and to keep well apart if they find that they have to go out—to prevent the virus from spreading. On top of this many are in any case fearful to go out, lest they catch the illness. Without a vaccine or therapeutic drugs, neither of which is guaranteed, countries therefore face a future of bouncing in and out of lockdown every few months, with infection rates ebbing and flowing in response. The result will be mounting death tolls, depressed economies and confidence-sapping uncertainty. This can, however, be partly ameliorated by extensive testing for the virus. Testing enables the government to keep tabs on the disease, reveals which social-distancing measures work, and, if those testing positive remain at home, instills confidence in the public that it is safe to go out…