The price of eggs at U.S. grocery stores has climbed to a record high, nearly doubling from a year ago, as outbreaks of bird flu have led to shortages by wiping out millions of hens.

Commercially available eggs pass through testing, grading and inspection, with extra layers of protection in California, specifically.

Avian influenza is in the same virus family as seasonal flu. Poultry has proven to be very sensitive to the virus, which results in high mortality.