Some shoppers are reporting bare shelves at grocery stores across Nova Scotia. And with the winter storms and road conditions over the past week, it's an issue at other grocery stores across the region. But some people are suggesting this is because of a vaccine mandate that went into effect Saturday for truck drivers crossing the Canada-US border. Sylvain Charlebois says it's not that simple. The Professor of Food Distribution with Dalhousie University says there's a confluence of issues affecting the supply chain right now.