Three shipments of Moderna's coronavirus vaccine were delayed from distribution after it was discovered that they did not maintain a stable temperature in transit.

All three shipments arrived in Texas last week and were originally set to be delivered ahead of Christmas. 

It was unclear how many total doses were affected, though the federal government did replace the shipments, Bloomberg News reported.

Moderna’s vaccine requires storage in temperatures between minus 13 degrees and 5 degrees Fahrenheit or between 36 degrees and 46 degrees Fahrenheit for up to 30 days before it must be discarded.

The Texas Department of State Health Services reported that delays have created the appearance that the state has only administered a small portion of the vaccines it has received, according to Bloomberg.

“Some of the shipments for week 2 were delayed and were not received by providers until
Monday and Tuesday of this week,” spokeswoman Lara Anton told Bloomberg.

Carrie Kroll, vice president of advocacy, quality and public health at the Texas Hospital Association, told Bloomberg that some hospitals in Texas are facing issues with tracking immunizations.

“It’ll look like there’s vaccine sitting on the shelf when it’s actually been administered,” Kroll
said.

The U.S. has experienced other obstacles in reaching its goal of vaccinating 40 million Americans by the first week of January as well. Earlier this month, 50 vials of the Moderna vaccine had to be thrown out in Wisconsin due to a medical center employee failing to return them to the storage freezer after initially taking them out to remove another item.

As of Tuesday, nearly 11,445,000 vaccine doses have been distributed in the U.S. and a total of 2,127,143 people have received their initial shot, according to the Centers for Disease Control and Prevention.