The FDA has learned of reports that some health care facilities are trying to stretch the number of limited doses by cutting them in half, extending the length of time between doses, or mixing and matching vaccines in order to immunize more people against COVID-19.

Pharmacist Marie Antonette Tambot prepares Pfizer-BioNTech COVID-19 vaccinations for healthcare workers at Seton Medical Center, Thursday, Dec. 24, 2020, in Daly City, Calif. (AP Photo/Jeff Chiu)