LONDON — The British government has announced plans for daily COVID-19 testing of critical food industry workers, allowing those who test negative to continue working even after they’ve been in close contact with people infected with the virus.

The government said Thursday night that it has identified priority locations, including the largest supermarket distribution centers, where testing will begin this week. The program will be expanded to as many as 500 sites next week.

The new policy seeks to avert food shortages as hundreds of thousands of people around the country are told to self-isolate by the National Health Service’s COVID-19 app, creating a “pingdemic” that has dominated headlines all week.

The move marks a reversal for Prime Minister Boris Johnson’s government, which until now had resisted pressure from food industry leaders who said they were being left shorthanded because so many of their workers were being told to self-isolate. While the government and supermarket bosses say there is no shortage of food, newspapers and TV news reports have shown pictures of empty supermarket shelves in recent days, raising fears of panic buying by anxious consumers.

“As we manage this virus and do everything we can to break chains of transmission, daily contact testing of workers in this vital sector will help to minimize the disruption caused by rising cases in the coming weeks, while ensuring workers are not put at risk,” Health Secretary Sajid Javid said in a statement.