Twenty-one shipments of the vaccine – or 11,900 doses — sent Sunday by a Texas-based distributor, McKesson Corporation, were deemed unusable after falling below the federally recommended range of minus 13 degrees to 5 degrees Fahrenheit.

“Although it is unfortunate that this vaccine will not be able to be used, we are pleased that the safeguards put into place to ensure the integrity of the vaccine worked,” the state’s chief medical executive, Dr. Joneigh Khaldun, said in a statement.

Khaldun said the incident marked the first report of a vaccine “potentially being compromised” during shipment to Michigan, where roughly 29,000 doses per day were doled out last week.