by David Leonhardt, Opinion Columnist The New York Times

More than 20,000 people have died from the coronavirus in each of these European countries: France, Italy, Spain and the United Kingdom. More than 17,000 have died in New York City. But in Germany — which is home to more people than any one of those other European countries and 10 times as many as New York — only about 6,000 have died.

How could that be? There are multiple reasons, but the biggest is probably the country’s approach to testing.

As Katrin Bennhold of The Times has written: By the time Germany recorded its first case of Covid-19 in February, laboratories across the country had built up a stock of test kits … Early and widespread testing has allowed the authorities to slow the spread of the pandemic by isolating known cases while they are infectious. It has also enabled lifesaving treatment to be administered in a more timely way. Testing is the key to every effective strategy for fighting the virus. It allows the sick to be treated effectively. It enables government officials and hospitals to focus their resources on the areas that need it most. And it makes sure that people who have the virus without symptoms — and can unknowingly spread it to others — can be isolated.

The troubled response to the virus in the United States began with testing failures, and there are still not nearly enough tests being conducted. Michael Osterholm and Mark Olshaker write in a new Op-Ed: “Far too few tests are available in the United States. Some are shoddy. Even the ones that are precise aren’t designed to produce the kind of definitive yes-no results that people expect.” The testing problem will need to be solved before states can return to normal — as some are now taking early steps toward — without sparking new outbreaks.