Waffle House announced it will be adding a $0.50 surcharge to all egg items on the menu sold at its more than 2,000 locations because of soaring egg prices caused by the bird flu.

The surcharge went into effect Monday.

In a statement, the comfort food franchise said the surcharge was triggered by the highly infectious virus, which has affected the chicken population and caused an egg shortage. More than 13 million hens have been lost or slaughtered since December following the bird flu outbreak, according to the Agriculture Department’s latest egg markets overview.

Economists and market analysts have cited the bird flu as the chief reason for the price spike, along with the typical consumer demand for eggs during the winter holiday season.

In the past year, the average price for a dozen eggs in the U.S. has jumped 50%, and the cost increase appears to have accelerated since November, the month Donald Trump was elected president, according to data from the U.S. Bureau of Labor Statistics.

“Consumers and restaurants are being forced to make difficult decisions,” Waffle House Inc. said in the statement.

The franchise said the $0.50 increase “is a temporary targeted surcharge” tied to the rise in egg prices, and that it “will adjust or remove the surcharge as market conditions allow.”

“While we hope these price fluctuations will be short-lived, we cannot predict how long this shortage will last,” the franchise said.

Pertinent to the food industry’s recovery and mitigating the spread of the virus is identifying cases of bird flu.

To assist with bird flu investigations, the Centers for Disease Control and Prevention has urged labs to determine whether people hospitalized with the flu have the virus or just seasonal influenza within 24 hours of admission.

This guidance has been in place since last fall, but many hospitals have been sending flu samples out for testing in bulk every few days. According to the CDC’s Dr. Nirav Shah, who is a senior advisor, acting principal deputy director at the agency, patients have often already been sent home by the time test results have come back.

“The more time that goes by, the more memories fade and the harder it is to identify a potential source,” Shah said during a news briefing last month. This can also mean that “their close contacts may be beyond the window for preventative medications like Tamiflu.”

The seasonal flu is raging in the United States right now, especially in the West, across the Midwest and deep into the Southeast, the CDC said last month.