Access to the "Alena" CBT-based therapy programme for 4 weeks. Each of the four therapy modules gradually became available on a weekly basis until all four were available in the final intervention week. Participants were instructed to complete one module per week. Each therapy module consisted of psychoeducational content, guided psychological reflection and perspective-taking exercises, and, where appropriate, skills training exercises such as attention training, public speaking, and exposure experiments to be completed in real life.

Waitlist control. Participants in this arm were given access to the CBT content at the end of the 4-week trial period.

This mobile application comprised CBT-based therapy for social anxiety based on the Clark and Wells model

The Intervention group was asked "Have you experienced any negative effects from using the Alena app? This could be a physical or emotional effect that you believe you have experienced as a result of using the app and/or engaging in the app therapy." Both groups were asked: "Have you experienced any new, serious negative health effects in the past week? This includes having to see your GP for a new reason, going to hospital, or being otherwise very unwell in terms of your physical or mental health." If participants responded positively to either question, they were prompted for additional details and to rate the severity of the experience.

The Intervention group was asked "Have you experienced any negative effects from using the Alena app? This could be a physical or emotional effect that you believe you have experienced as a result of using the app and/or engaging in the app therapy." Both groups were asked: "Have you experienced any new, serious negative health effects in the past week? This includes having to see your GP for a new reason, going to hospital, or being otherwise very unwell in terms of your physical or mental health." If participants responded positively to either question, they were prompted for additional details and to rate the severity of the experience.

Participants were asked how satisfied they were with the app overall (Likert rating scale from very dissatisfied to very satisfied); how helpful they found the app (Likert ratings from very unhelpful to very helpful); how likely they would be to recommend the app (Likert ratings from very unlikely to very likely); how easy they found using the app (Likert ratings from very difficult to very easy); whether they got to the end of the weekly exercise (yes/no), and what got in the way of completing the exercises, with options provided.

The SPIN was designed to assess the full spectrum of symptoms that characterise social anxiety, including fear, avoidance and physiological components. Total score ranging from 0 to 68, with higher scores indicating a worse outcome.