ISRCTN15317247.

Study name	Using text messages to boost COVID‐19 vaccine booking rate
Starting date	3 June 2021
Contact information	Hannah Behrendt, hannah.behrendt@bi.team
Methods	Study design: randomised controlled trial Type of publication: trial registration Setting: via phone messages Country: UK Language: English
Intervention	Behaviourally‐informed SMS vaccination information Control SMS invitation behaviourally‐informed SMS vaccination invitation Top of queue Convenience Reserved Top of queue + convenience Reserved + convenience Front of queue
Population	Population: general population Inclusion criteria: 18 to 29 years, registered in the NHSEI system with a mobile phone number
Outcomes	Primary outcome Booking of COVID‐19 vaccination appointments within 72 hours following the invitation Secondary outcomes Receiving the first‐dose within 14 day following the SMS invitation Booking of COVID‐19 vaccination appointment within 14 days following the SMS invitation
Estimated completion date and number of participants	4270,000 planned, completed 1 July 2021
Notes	COI: NR Funding: National Health Service