An ongoing bird flu epidemic has forced farmers to kill millions of egg-laying hens, leading to a serious shortage. The low supply of eggs means customers end up paying quite a bit more than usual at the supermarket. In some places, eggs now cost more than double what they did six months ago.

According to the U.S. Department of Agriculture’s (USDA) price outlook, egg prices are predicted to increase by 20.3 percent by the end of 2025. This isn’t necessarily a surprise, since retail egg prices were up by 8.4 percent in December.

The average price of a dozen large, grade-A eggs was $4.15 in December, up from $3.65 in November, according to the Bureau of Labor Statistics. Egg prices were also up more than 36% year-over-year in December, according to the Consumer Price Index.