The Moderna COVID-19 vaccine is shown at the Tequesta Fire Department on Friday, Jan.15, 2021 in Tequesta, Fla. Credit: Greg Lovett / Northwest Florida Daily News via AP

Approximately 4,400 Moderna coronavirus vaccines sent to Maine are being replaced after they were potentially spoiled after exceeding a maximum temperature, health officials said Tuesday.

Thirty-five sites administering vaccines received compromised doses that have not yet been used, said Maine Center for Disease Control and Prevention Director Nirav Shah. The doses are shipped with an electronic device indicating if the vaccines ever go above a maximum required temperature of 4 degrees below zero, which alerted officials to the issue.

Shah said the state and federal governments are working with Moderna to find out if the vaccines can be used, but held the doses back for now as a precaution. Those sites will be getting replacement doses as soon as today, he said. He said other states including Connecticut had a similar problem with some doses.

Health officials are looking into where in the process the vaccines were potentially compromised, Shah said. He believed it happened during the shipping or processing stage, not with providers or when the vaccines went through the Maine CDC.

The Moderna vaccines are usually sent to smaller health care providers that might not have the ability to store the Pfizer vaccine, which requires an ultra-cold freezer to remain viable. They can also be sustained with the help of dry ice. Moderna vaccines are also sent in packs of 100 — Pfizer comes in 975 packs — that allow easier storage for smaller clinic.

The amount of potentially compromised vaccines is about a quarter of the vaccines Maine ordered last week and half of the Moderna order, according to a news release. The state has been getting tens of thousands of vaccines each week, often less than expected.

Maine recently expanded its vaccine program to include older Mainers and those with health conditions making them more vulnerable to the virus, but that process is expected to move relatively slowly if vaccine allocation does not increase. Last week, it was revealed that a reserve of vaccines that the federal government planned to release did not exist.

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