The question for a world enduring the variant’s astonishing surge is how can we discover the next one early enough to stop its spread. Currently, the hunt for coronavirus variants is too slow and sporadic. Scientists in a handful of countries — South Africa, Botswana the United States and others — monitor patterns in case counts and regularly sequence samples of the virus from infected people to see whether there are notable genetic changes. The results of these analyses can be shared within a global network, such as GISAID, an international community of scientists who openly share data on disease variants, to compare coronavirus sequences from around the world.

By the time this happens, variants are often already spreading in a community and most likely beyond it. This analysis process is like testing every piece of hay in a stack to see whether it’s a needle — or, really, the equivalent of choosing and testing just 1 percent of the haystack.

But there are places to look that may help scientists find new variants even faster: sewage and the air. People can shed the coronavirus in their feces and their exhaled breath. As a result, the virus can be spotted before people have been tested or developed symptoms.