McKesson was selected by the U.S. government in August 2020 to operate as the centralized distributor for frozen and refrigerated COVID-19 vaccines and ancillary supply kits needed to administer them. In December 2020, McKesson began distributing the ancillary supply kits for Pfizer BioNTech's COVID-19 vaccine. Later that month, the company began distributing Moderna's COVID-19 vaccine and ancillary supply kits.