Two terminals for the Port of Houston were shut down for a day this month after an employee tested positive for coronavirus, and Pennsylvania briefly closed most of its truck stops and service areas to slow the spread of the virus, threatening to also slow the distribution of food and other goods. Some meat packagers around the country were at three-fourths capacity because of illness.

In these and other small ways, the coronavirus has begun affecting the nation’s food supply chains, raising the potential that as the virus spreads, it will become harder to get food into stores from both American producers and ones abroad.

So far, the worst of the problems in the United States have been temporarily empty shelves at some stores. But the consulting company Fitch Solutions says that it sees “risks at all levels of the supply chain, from production to trade” that could lead to a “re-acceleration in food price inflation globally.” The United Nations Food and Agriculture Organization says it expects disruptions in food supply in April and May.

How bad could it get in the United States? What happens in California and abroad could provide a big part of the answer.