October 3, 2024

Since the onset of the Highly Pathogenic Avian Influenza A H5N1 (H5N1) outbreak in dairy cattle earlier this year, researchers across the federal and state governments have been working to understand the prevalence of H5N1 in the U.S. milk supply. This week, states were invited to participate in a new study that will generate data to aid in the understanding of the prevalence of H5N1 in bulk raw cow’s milk received by dairy processing facilities across the nation. Dubbed “the silo study,” the information garnered from this research can help inform the national strategy to control the spread of the virus to other dairy cattle and avian flocks, and to identify any viral transformations.

Beginning October 28, Grade “A” raw cow’s milk from participating states intended to be pasteurized will be sampled from raw milk storage silos at dairy processing facilities, over a six-week period.

This double-blinded study is designed for data-gathering purposes only, with no intent or means of traceback or trace forward. Neither participating nor non-participating states or facilities will be identified as part of this project. Samples will be collected, double blinded, and sent to the U.S. Department of Agriculture (USDA) National Veterinary Services Laboratory for analysis.

A robust milk sampling program exists within the regulatory framework of the Pasteurized Milk Ordinance (PMO) and the federal-state cooperative Grade “A” milk program. The silo study seeks to leverage the Grade “A” Milk Safety Cooperative Program and its members to further understand the prevalence of HPAI in cow’s milk that is sent for commercial processing and stored at dairy processing facilities prior to pasteurization.

State participation in the silo study is voluntary, but it is hoped that states will want to contribute to this important project. The FDA, National Conference of Interstate Milk ShipmentsExternal Link Disclaimer (NCIMS), and USDA will review the results of the silo study and are committed to providing study results in the near future.

The FDA’s ongoing assessments of the milk safety system continue to confirm that pasteurization is effective at eliminating infectious H5N1 virus in dairy milk. In addition to this silo study, the FDA is funding research activities (see the September 26 update) designed to ensure the continued effectiveness of the federal-state milk safety system. The FDA will continue to follow a sound, scientific process to inform the agency’s public health decisions related to milk safety during the first-of-its-kind outbreak of H5N1 in dairy cattle. The FDA remains committed to providing further updates on research efforts.