This was the first RCT where follow up was conducted entirely within a TRE. The study’s novel design meant GP practices and patients did not have to return any data, as all analysis was conducted via the OpenSAFELY TRE. OpenSAFELY TRE gives researchers access to 40% of the English population’s anonymous health records.

Germ Defence is a behaviour change website that gives practical advice on how to reduce the spread of infection in the home. It was found to be effective in reducing the spread of seasonal and swine flu in a previous RCT.

During the trial, half of all GP practices in England were randomly selected to send out the Germ Defence website link to their patients in the autumn of 2020 (the intervention arm). The remaining practices were asked to do the same in spring 2021.

Researchers then looked at rates of respiratory infection, including coronavirus and seasonal flu, in both groups of practices. They also looked at other outcomes including how often people visited their GP and used antibiotics.

The study team gave every GP practice a unique link to the website that they could send on to their patients. Using these unique links meant the team could see whether the patients were accessing the intervention without the practices needing to report back.

Website statistics showed that around 460 practices shared their link with patients, who then went on to use the site over 300,000 times (with an average user satisfaction score of 7.52 out of 10). This was 16% of the practices invited, but the research team had hoped that at least 25% would participate. Participation below this level means no firm conclusions could be made about the effectiveness of the intervention.

While no evidence of a difference in infection rates was observed between the two groups, the findings are nevertheless important. The trial design allowed the team to safely recruit GP practices during the pandemic. They used several new techniques to reduce the burden on practices and improve the number who could take part in research. These included:

• Recruiting practices via email, removing the lengthy process of contacting individual practices (although to avoid overwhelming practices this method should only be used when rapid enrolment is necessary)
• Using unique GP practice weblinks, which allowed researchers to understand how each practice used the intervention without needing to contact the practice
• Using national routinely collected patient record data accessed through OpenSAFELY, to analyse anonymised GP records securely - demonstrating that randomised trial follow-up can be done in a TRE

Jeremy Horwood, Professor of Social Science and Health at the Centre for Academic Primary Care, University of Bristol, one of the lead authors of the study, said:

“The NHS was under immense strain during the pandemic, including GP practices, so conducting a large trial to roll out Germ Defence rapidly was challenging. GP practices didn’t have much spare time for research. So we tried to design a trial that required minimal work from practices, so more could take part. We hope this novel efficient trial design will be valuable for rolling out other interventions rapidly and safely.”

Ben Ainsworth, Associate Professor of Psychology, University of Southampton and the other lead author, said:

“It’s important that new treatments and interventions can be evaluated rapidly. In this project the scientific experts worked with a range of healthcare and research professionals, patients and members of the public to ensure that we could do this without compromising data security and patient safety.”

The research was funded by the UKRI,National Institute for Health and Care Research Applied Collaboration ( NIHR ARC) West, and NIHR Health Protection Research Unit in Behavioural Science and Evaluation at University of Bristol.

Paper: 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 by Ben Ainsworth, Jeremy Horwood et al. Published in Implementation Science. December 2023.