VANCOUVER -- Fraser Health’s online system for booking COVID-19 vaccine appointments is down, and has been for at least 24 hours.

This, in the health authority worst hit by the coronavirus.

According to its website, the system is “offline as we undertake important maintenance to ensure there is a comprehensive transition to the provincial online booking system and registration tool set to launch next week.”

Burnaby resident Cheryl Moses says she first tried to access the system on Monday morning around 9 a.m. but it was down, and has remained that way.

Fraser Health’s website says the online portal is expected to be back up and running at 7 p.m. Tuesday, March 30.

Until the online system is restored, residents are being asked to call by phone instead, according to instructions on the website. But Moses says the phone line is of little use because she hasn’t been able to get through, either yesterday or today.

“What I got was, ‘We are very busy so call back at another time,’” she said.

CTV News Vancouver called Fraser Health’s vaccination booking phone line just before 4 p.m. on Tuesday and received a message instructing callers to hang up and try again later, or to book online.

On the booking website, Fraser Health says it opened vaccine booking slots to an additional cohort on Monday -- those who are “clinically extremely vulnerable.” The day before, on Sunday, it also opened to those who are 73 or older or who are Indigenous and 55-years-old and up.

This likely resulted in an increase in the number of people trying to access the system.

In a news statement, Fraser Health acknowledged some of the difficulties.

“We understand this transition (to the provincial booking system) coupled with high volumes has caused some challenges with people accessing the system," the health authority said.

“We appreciate everyone’s patience as we schedule very sizable populations into immunization appointments.”