“Like many retailers, we are carefully managing supply of eggs due to current industry challenges,” McDonald’s said in a Facebook post. “We are working hard with our Aussie farmers and suppliers to return this back to normal as soon as possible.”

Known fondly as Macca’s on the other side of the International Date Line, the fast-food chain has 970 locations in Australia, but more than just fast-food fans have been impacted by the shortage. Australian supermarket chain Coles Group began limiting customer purchases to two cartons of eggs per day after the highly contagious avian flu H7N3 (a separate strain of the H5N1 flu, which has not been found in Australia) was detected at five farms on the continent. Since the virus first began spreading in May, the flu has impacted 11 poultry facilities, mostly egg farms. 

Trying to contain the spread of the disease, which can be fatal to livestock including cows, poultry farms have quarantined their animals and carried out mass euthanasia of over half a million chickens. About 450,000 eggs are destroyed daily to contain the virus. But while those sound like big numbers, industry experts said the most important meal of the day isn’t under threat yet.

“Consumers can be assured there’s still over 20 million hens under the care of hundreds of egg farmers across Australia that will continue to work hard to ensure there’s eggs on shelves,” Rowan McMonnies, managing director of industry group Australian Eggs, said last week.

What about all-American fast food?

The avian flu has also wrought havoc in the U.S., though fast-food breakfasts are secure at the moment. From February 2022 to June of this year, bird flu killed 96 million backyard and commercial birds nationwide. Cal-Maine Foods, the nation’s biggest egg producer, killed 1.6 million laying hens, almost 4% of its flock, and temporarily halted operations in April after detecting bird flu. 

For most Americans, the looming epidemic won’t impact eating patterns. U.S. health officials tested milk sold in stores to check for traces of the virus, ultimately telling consumers that milk should be pasteurized before being imbibed. Hamburgers cooked between 145 and 160 degrees Fahrenheit were likewise found safe to consume, as were cooked chicken and eggs.

Though these staple foods don’t pose a threat to one’s health, U.S. consumers are feeling the impact on their wallets as egg prices rose over 15% to $2.99 for a dozen large Grade A eggs from January to April, according to Bureau of Labor Statistics data. While mass euthanasia ensures the safety of flocks, it also makes supply precious, as replacing lost birds is time-consuming.

“You’re taking out all the baseline egg production for up to three months at a time,” Andrew Stevens, agricultural economist at the University of Wisconsin, told CBS MoneyWatch. “You’re paying for that lag time it takes to shore up and build back up production.”

While fast-food menus in the U.S. have been impacted by egg and livestock shortages, changes are starting to creep into the industry. Chick-fil-A began moving away from its “no antibiotics ever” promise in March, instead embracing an industry standard of only using antibiotics if a chicken needs to be treated for illness. It followed in the footsteps of poultry giants Pilgrim’s Pride and Tyson Foods, as farmers try to maintain the health of their close-quartered chickens amid rampant disease.

With the industry scrambling to convey a sense of stability, McDonald’s has assured customers some things on its menu will never change.

“PS,” McDonald’s Facebook post said. “Hash Browns are still available all day.”