By CBS3 Staff

NORRISTOWN, Pa. (CBS) — A massive Moderna COVID-19 vaccine allocation mistake in Pennsylvania could affect more than 100,000 vaccination appointments in the commonwealth. Montgomery County has been using the Moderna vaccine at its two mass vaccination sites, which is again having to close.

Health officials say without a centralized system from the commonwealth — currently, distribution is essentially left up to individual providers — issues like this are going to continue to happen.

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“The logistical challenges of operating our mass vaccination clinics is changing weekly,” Montgomery County Board of Commissioners Chair Dr. Valerie Arkoosh said.

For the second time in as many weeks, Montgomery County has been forced to close one of two mass vaccination sites because of a supply shortage.

“Due to a combination of inclement weather and not receiving enough first doses of vaccine this week, we have decided to close our first dose clinic at Norristown High School this Thursday and Friday,” Arkoosh said.

But this time, the problem doesn’t stop there. The county is closing its second dose site at Montgomery County Community College on Thursday.

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“We have been told that we will not receive a sufficient amount of second dose Moderna vaccine to cover the 5,279 people scheduled for second doses next week,” Arkoosh said.

On Wednesday, Pennsylvania health officials said unnamed providers mistakenly gave out 100,000 second-doses as first doses. Montgomery County says anyone who had an appointment will be notified by email and automatically rescheduled in time to ensure full immunity, which the CDC says is up to 42 days. They’re also swapping which vaccine they will be using going forward, at least for now.

“Due to Moderna supply issues we will now be distributing Pfizer vaccine for first doses starting Tuesday, Feb. 23,” Arkoosh said. “This switch is based solely on the which first dose vaccine is available to us from the Pennsylvania Department of Health.”

Thirty-four states in total are delaying or canceling vaccine appointments due to weather or supply issues. That includes New Jersey. Monmouth County announced appointments for Thursday will be rescheduled due to shipment delays of the shots.

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CBS3’s Alicia Roberts reports.