This week, the first round of Pfizer-BioNTech COVID-19 vaccine, some 4,875 doses, was distributed by San Joaquin County Public Health to the county’s seven hospitals, who inoculated their health care workers. Some 1,950 doses went to St. Joseph’s, which has a deep freezer. Pfizer’s vaccine and the Moderna vaccine, which soon is expected to be approved by the Food & Drug Administration, are RNA vaccines, a technique that never has been used before in a human vaccine but is extraordinary and appears to be a highly effective technique, Neeley said. Neeley explained the RNA vaccine mimics the virus’ mechanism of action but does it in an extraordinarily safe way, “because you’re not producing a live virus,” he said.