Long-standing supply chains for everyday grocery items have been upended as the pandemic sickened scores of workers, forced factory closures and punctured the carefully calibrated networks that brought food from farms to store shelves. Even while some of the sharpest price hikes have eased somewhat, the overall effects are being felt most acutely by the nearly 30 million Americans who saw their $600 enhanced unemployment benefit expire last Friday — exacerbating concerns that the recession's long tail could worsen food insecurity for years to come.