Implementing Germ Defence digital behaviour change intervention via all primary care practices in England to reduce respiratory infections during the COVID-19 pandemic: an efficient cluster randomised controlled trial using the OpenSAFELY platform
Authors: Ainsworth Ben , Horwood Jeremy , Walter Scott R. , Miller Sascha , Chalder Melanie , De Vocht Frank , Denison-Day James , Elwenspoek Martha M. C. , Curtis Helen J. , Bates Chris , Mehrkar Amir , Bacon Seb , Goldacre Ben ,   The OpenSAFELY Collaborative, Walker Alex J. , MacKenna Brian , Inglesby Peter , Morton Caroline E. , Morley Jessica , Hickman George , Croker Richard , Evans David , Ward Tom , DeVito Nicholas J. , Fisher Louis , Green Amelia C. A. , Massey Jon , Smith Rebecca M. , Hulme William J. , Davy Simon , Andrews Colm D. , Hopcroft Lisa E. M. , Drysdale Henry , Dillingham Iain , Park Robin Y. , Higgins Rose , Cunningham Christine , Wiedemann Milan , Nab Linda , Maude Steven , Butler-Cole Ben F. C. , O’Dwyer Thomas , Stables Catherine L. , Wood Christopher , Brown Andrew D. , Speed Victoria , Bridges Lucy , Schaffer Andrea L. , Walters Caroline E. , Rentsch Christopher T. , Bhaskaran Krishnan , Schultze Anna , Williamson Elizabeth J. , McDonald Helen I. , Tomlinson Laurie A. , Eggo Rosalind M. , Wing Kevin , Wong Angel Y. S. , Tazare John , Grint Daniel J. , Langan Sinead , Mansfield Kathryn E. , Douglas Ian J. , Evans Stephen J. W. , Smeeth Liam , Walker Jemma L. , Mahalingasivam Viyaasan , Cowling Thomas E. , Herrett Emily L. , Costello Ruth E. , Zheng Bang , Parker Edward P. K. , Mathur Rohini , Forbes Harriet , Cockburn Jonathan , Parry John , Hester Frank , Harper Sam , Craggs Pippa , Amlôt Richard , Francis Nick , Little Paul , Macleod John , Moore Michael , Morton Kate , Rice Cathy , Sterne Jonathan , Stuart Beth , Towler Lauren , Willcox Merlin L. , Yardley Lucy 
Published: December 2023

Abstract
Background
Germ Defence (www.germdefence.org) is an evidence-based interactive website that promotes behaviour change for infection control within households. To maximise the potential of Germ Defence to effectively reduce the spread of COVID-19, the intervention needed to be implemented at scale rapidly.

Methods
With NHS England approval, we conducted an efficient two-arm (1:1 ratio) cluster randomised controlled trial (RCT) to examine the effectiveness of randomising implementation of Germ Defence via general practitioner (GP) practices across England, UK, compared with usual care to disseminate Germ Defence to patients. GP practices randomised to the intervention arm (n = 3292) were emailed and asked to disseminate Germ Defence to all adult patients via mobile phone text, email or social media. Usual care arm GP practices (n = 3287) maintained standard management for the 4-month trial period and then asked to share Germ Defence with their adult patients. The primary outcome was the rate of GP presentations for respiratory tract infections (RTI) per patient. Secondary outcomes comprised rates of acute RTIs, confirmed COVID-19 diagnoses and suspected COVID-19 diagnoses, COVID-19 symptoms, gastrointestinal infection diagnoses, antibiotic usage and hospital admissions. The impact of the intervention on outcome rates was assessed using negative binomial regression modelling within the OpenSAFELY platform. The uptake of the intervention by GP practice and by patients was measured via website analytics.

Results
Germ Defence was used 310,731 times. The average website satisfaction score was 7.52 (0–10 not at all to very satisfied, N = 9933). There was no evidence of a difference in the rate of RTIs between intervention and control practices (rate ratio (RR) 1.01, 95% CI 0.96, 1.06, p = 0.70). This was similar to all other eight health outcomes. Patient engagement within intervention arm practices ranged from 0 to 48% of a practice list.

Conclusions
While the RCT did not demonstrate a difference in health outcomes, we demonstrated that rapid large-scale implementation of a digital behavioural intervention is possible and can be evaluated with a novel efficient prospective RCT methodology analysing routinely collected patient data entirely within a trusted research environment.

Trial registration
This trial was registered in the ISRCTN registry (14602359) on 12 August 2020.