How to do efficient trial design in a pandemic? National implementation via primary care of Germ Defence digital behaviour-change intervention to reduce the spread of COVID-19

Talk Code: 
Jeremy Horwood
Melanie Chalder, Ben Ainsworth, James Denison-Day, Frank de Vocht, Martha Elwenspoek, Pippa Craggs, Rachel Denholm, Jonathan Sterne, John Macleod, Cathy Rice, Beth Stuart, Michael Moore, Paul Little, Gulliford, Martin, Nicholas Francis, Merlin Willcox, Sascha Miller, Richard Amlôt, Lucy Yardley
Author institutions: 
Univeristy of Bristol, University of Bath, Univeristy of Southampton, King's College London, Public Health England


To help reduce the spread of COVID-19 infections, people should adopt protective behaviours at home (e.g. self-isolation, handwashing, cleaning and disinfecting). There is currently limited support to help individuals conduct these behaviours. Germ Defence is an evidence-based behaviour change website that provides scientifically proven advice on infection control at home. A clinical trial of 20,000 people during the time of the H1N1 pandemic and seasonal ‘flu showed that using Germ Defence successfully reduced the number and severity of infections in the home as well as the need for primary care consultations and antibiotics. We are now examining via an efficient randomised controlled trial (RCT) whether the Covid-19 updated version of Germ Defence is effective at reducing infections if disseminated via GP practices.


The Germ Defence cluster RCT is investigating the effects of randomising dissemination of the Germ Defence website via GP practices on rates of respiratory infection, including COVID-19. Due to the need to rapidly implement the intervention, we adopted a novel efficient trial design. No practice or patient recruitment is required as all outcomes are assessed using anonymous data and GP practices are not required to send the research team any data. Practices are given individualised Germ Defence weblink which will be used to track website usage in each practice to measure roll out. Website analytics will be used to measure uptake of the intervention and types of use. National routinely collected patient record data extracts via NHS Digital will be used to examine whether practices who received the Germ Defence intervention reported decreased respiratory infections.We randomised all GP practices in England to receive an email asking them promote Germ Defence to their patients (N=3292) or usual care (N=3290). Emails were piloted within several GP practices and included example messages (e.g. via text or email) that could be used to encourage patients to use Germ Defence. Intervention practices were contacted throughout Autumn/Winter 2020 and usual care practices in March 2021.


The trial was endorsed by Chris Whitty is Chief Medical Officer for England, as a national priority project and adopted by the CRN as an Urgent Public Health portfolio study. These endorsements opened doors and allowed access to information. However, despite extensive piloting of the email to practices and message to patients there were significant practical barriers to overcome, such as practice being contacted directly by the research team and not via CRNs and the individualised Germ Defence weblink being perceiving as spam by staff and patients.


This is a novel strategy for rapidly implementing and evaluating a national digital behaviour-change health intervention via primary care.

Submitted by: 
Jeremy Horwood
Funding acknowledgement: 
This research is funded by UKRI Coronavirus Rapid Response Call (CV220-009) and National Institute for Health Research, Applied Research Collaboration West (NIHR ARC West) and NIHR Health Protection Research Unit (HPRU) in Behavioural Science and Evaluation.