The Biden administration is considering the use of vaccines in poultry as one option to address a bird flu epidemic that has killed millions of chickens and contributed to high egg prices.

“There are a range of options the United States regularly considers when there is any outbreak that could affect the security and safety of the United States’ food supply,” a White House National Security Council spokesperson said in a statement on Monday. “Right now, we are focused on promoting and enhancing high-impact biosafety practices and procedures.”

Those safety procedures include efforts to prevent transmission of the bird flu through enhanced disinfection among workers.

The Centers for Disease Control and Prevention (CDC) is monitoring the threat of the avian flu’s risk to humans, which is considered to be low. The U.S. Department of Agriculture has been responding whenever the flu is detected among bird populations, and the agency has begun testing potential poultry vaccines. No such vaccine is authorized yet.

The New York Times reported on Monday that the Agricultural Research Service is working to develop in-house vaccine candidates, which could be deployed more quickly than newly developed ones. The agency is not expected to have its first round of results until May, the Times reported.

The bird flu outbreak began last year and has infected more than 50 million birds across 47 states, both in the wild and on farms. The disease has led to the slaughter of millions of infected birds, which in turn has fed into an increase in the price of eggs, turkey and chicken, as well as a loss in income for farmers.

The average price of a dozen eggs was $4.82 in January, up from an average of $1.93 a year earlier, according to Purdue University data.