A Walgreens spokesman said they believe the disruption was caused by an influx of people wanting to schedule an appointment and cause the server to crash.
“We are committed to a seamless scheduling experience to achieve the shared goal of vaccinating our most vulnerable population as quickly as possible,” the spokesman said.
The disruption comes as U.S. pharmacies such as Walgreens and CVS prepare for another million doses of vaccine that the White House promised last week.
To date, more than 32 million Americans have received at least one dose of COVID-19 vaccine.
Walgreens told ABC News that they will start accepting appointments for shots from Tuesday through Friday, prioritizing health care workers over the age of 65 and people with a pre-existing condition.
ABC News contributed to this report
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