Last Thursday, half a million Stockholmers woke up to a text message from the healthcare app Always Open.

In the text message, the recipient was asked to log in to the app to participate in a survey of the quality of care.

Once inside the app, many were met by an offer to book their fourth dose of vaccine.

- It was a bug, it was like that for those who did not have an updated version of the app, says Sophie Enerskog, press officer at Stockholm County's healthcare area, SLSO.

How many were affected by the bug, ie how many people logged in and how many of them had an old version of the app, is not known.

Today, a new text message was sent out with a correction to the 1,200 people who were still incorrectly booked for their fourth dose.

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Three questions about the vaccination.

Photo: SVT / TT