Limitations
infection, word of mouth
INFECTION
This ‘low burden’ design comes with risks. Evaluating an accessible behavioural intervention that can be passed on via multiple communication pathways means we could not prevent people from using the intervention who were not from our randomised intervention group, nor could we control broad contextual factors that may have led to increased contamination (such as the frequent public health communications about Germ Defence during the study period, users sharing the website with other members of the public or interlinked healthcare services) sharing website details with, e.g. practices randomised to the control group). The nature of behavioural interventions means their core behavioural functions can be communicated through means other than the intervention (for example word of mouth) which would have been outside of our randomisation procedure—but in contexts outside of clinical research would be important communication mechanisms. In our trial, it is likely that such contamination could have reduced possible differences between our intervention and control group. Asking people to register to use Germ Defence could have been a method to control for contamination, but this could also be a barrier to using the intervention and reduced its use. Future research should aim to monitor and control contamination; however, this was not possible within our pragmatic trial of a public health intervention during a pandemic.Despite the unusually rapid set-up and implementation of this study, Germ Defence was rolled out through primary care over 6 months after the start of the COVID-19 pandemic. It is likely that by this point in time, most people who were concerned about infection control in the home may have already obtained all the advice they wanted and needed. Additionally, the lack of lengthy individual practice enrolment processes may have meant that many practices did not have inclination or time to properly engage with the study, given the need to maintain enhanced infection control measures reduced capacity that were increasing pressure on practices during the study period [However, this means our design accurately reflects ‘real-world’ uptake of such interventions outside of usually tightly constrained trial environments. Further research should use implementation frameworks to understand how to further improve rapid adoption and implementation [