Maine health officials discovered that a majority of Moderna vaccine shipments received across the state on Monday were not kept adequately cold during transport, meaning 4,400 doses may have to be thrown out.

Dr. Nirav Shah, director of the Maine Center for Disease Control and Prevention, made the announcement during a "sad and somber" coronavirus briefing on Tuesday and said the problem extends to other states as well.

Shah said 35 of the 50 sites that received the vaccine a day earlier reported that "the thermometer on the outside of the boxes ... showed that at some point the required minimum temperature had been exceeded."

Moderna's vaccine vials are supposed to remain at frozen temperatures between -25°C and -15°C (-13°F and 5°F), according to the U.S. Centers for Disease Control and Prevention.

An ongoing investigation found the temperature problem "is not something on the Maine CDC or state of Maine side," Shah said. That means the temperature breach occurred during packaging or shipping, he explained.

The chain of distribution as explained by Shah is fairly straightforward: Boxes of the vaccine are transported from Moderna's manufacturing facilities — the majority of which are located in Massachusetts — to a distribution point where the cargo is farmed out to various courier companies that make deliveries to locations designated by the Maine CDC, or other state sites.

"At each step along the way, these boxes of vaccines have numerous types of tracking and temperature monitoring tools around them," Shah said. "If at any point in that journey ... from the site of [the] manufacturer to someone's arm here in Maine ... conditions are not optimum, that there are processes in place so that we know that the vaccine is not given to somebody."

"This is how the system is designed," he added.

Maine residents who were scheduled to receive the injections were contacted and told the inoculations would be postponed, Shah said. He added that the White House Operation Warp Speed program is already sending replacement doses.

It is unclear if the vaccine doses will have to be thrown out or if they can still be used. The U.S. CDC's instructions note that "vaccine vials may be stored in the refrigerator between 2°C and 8°C (36°F and 46°F) for up to 30 days before vials are punctured."

However, a thawed vaccine cannot be refrozen.

As of Tuesday, there are 34,262 COVID-19 cases in Maine and 519 deaths associated with the disease.

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