The government vaccine portal crashed a few minutes after opening on Wednesday due to heavy traffic, angering thousands of people who were trying to arrange jab appointments.

It was unable to reopen until 5pm. The portal had opened for people aged 61 and above but it crashed soon afterwards because it could not handle the number of applicants. Close to 19,400 vaccines were made available at the time for 25,000 eligible people.

By the time it crashed, all the slots for Pfizer and Moderna vaccines had been exhausted. Only AstraZeneca jabs, round 15,000, were available when it reopened, and people reported having no trouble making an appointment at that stage.

AstraZeneca has become the least popular of the vaccines due to negative publicity surrounding a series of side effects related to rare blood clots. The European Medicines Agency on Wednesday said it had found such a link but reiterated previous statements that the benefits of the vaccines far outweighed the risks.

Research and Innovation and Digital Policy Minister Kyriacos Kokkinos said in the morning that close to 4,000 appointments were made in the first two and a half minutes the portal opened, the overwhelming majority for Pfizer and Moderna vaccines.

Kokkinos said the system was handling hundreds of requests per second, as people were trying to secure a slot with those two vaccines. Pfizer and Moderna vaccines were no longer available, Kokkinos said, but there were 15,000 AstraZeneca jabs when the portal reopened later Wednesday.

Following the collapse, the portal was taken offline so that techies could identify and resolve the problem.

The crash also affected the Gesy portal, as the two shared the same platform. The problem emerged because the OTP or one time password, was the same system for both.

Speaking on state radio earlier Wednesday, Kokkinos said the system overloading was not an excuse.

“I’ve told my people, when the platform opens, if I have 25,000 available vaccines, it should be able to serve 150,000, to have a cushion that is, because there are people who enter from two or three separate accounts for the same person,” he said.