A bellwether is an indicator of trends. For example, an increase in gasoline sales might indicate future auto travel activity. Sales at certain retailers or other businesses may serve as as a bellwether to analyze broader trends across the retail industry.
Now there may be a good bellwether for predicting the spread of coronovirus. Jesse Edgerton, an economist with JPMorgan Chase, did some research and found the level of spending in restaurants three weeks ago – most notably in-person versus online – was the strongest predictor of a surge in coronavirus cases during that time. I think he’s on to something. As reported in a June 26, 2020 USA Today article, “Based on spending by 30 million Chase credit and debit cardholders, Edgerton found that higher spending in supermarkets predicted a slower spread of the virus, suggesting consumers are practicing “more careful social distancing in a state.”