Across the country, shoppers in grocery stores are facing empty shelves and higher prices for what has traditionally been an inexpensive source of protein: eggs.

And it’s likely to get worse.

Volatile egg prices have been a part of the grocery shopping experience partly because of inflation, but also because of an avian influenza, or bird flu, that made its way to the United States in 2022. That influenza, caused by the H5N1 virus, has infected or killed 136 million birds thus far.

But the outbreak has recently intensified. More than 30 million chickens — roughly 10% of the nation’s egg-laying population — have been killed in just the last three months, to prevent the spread of the disease. It could take months before the supply of egg-laying chickens returns to the normal level of around 318 million, roughly the equivalent of one chicken per person.

The steep drop in the number of egg-laying chickens has caused a sharp spike in wholesale egg prices. Grocery stores and restaurants are now paying around $7 for a dozen eggs — a record level, up from $2.25 last fall, according to Expana.

While customers have noticed higher egg prices — the cost of eggs for consumers is 37% higher than a year ago — they have not yet felt the full impact of the shortage. Grocery stores typically price products such as milk and eggs as “loss leaders,” meaning they are sold for less than the wholesale price that stores pay, to entice customers into a store.

Karen Meleta, a spokesperson for Wakefern, a retailer-owned supermarket cooperative whose stores include ShopRite and Gourmet Garage, said in an emailed statement that the grocer has tried to maintain prices on eggs, but that it’s a “difficult thing to balance, particularly given the volatility of the market and the uncertainty resulting from these continued outbreaks.”

Around the country, shoppers are finding empty shelves or limits on the number of cartons they can purchase. That can create panic and lead to stockpiling eggs out of fear that shoppers may not find them later.

During the presidential campaign, Donald Trump blamed the Biden administration for inflation and promised to bring down prices for consumers. The spread of bird flu will make that pledge more difficult. Last week, United Egg Producers, the lobbying arm for egg producers, urged Congress and the Trump administration to move quickly to form a national strategy to battle the bird flu, including more funding for faster testing at state and federal levels, and development of potential vaccines.

At her confirmation hearing Jan. 23, Brooke Rollins, who is Trump’s nominee for secretary of agriculture, told senators that among her top priorities was to “immediately and comprehensively get a handle on animal disease outbreaks,” though she did not provide details.

Federal health officials have been closely watching the latest strain of bird flu that is lethal to chickens and also has been found in cattle, which typically recover from the flu with treatment.

Currently, the Centers for Disease Control and Prevention says the risk to humans remains low. Pasteurized milk and eggs are safe, as long as the eggs are cooked to appropriate temperatures to kill bacteria and viruses, but the cost is likely to climb higher and gaps on store shelves are likely to grow, analysts warn.