Contact tracing apps unlikely to contain COVID-19 spread

Contract tracing apps used to reduce the spread of COVID-19 are unlikely to be effective without proper uptake and support from concurrent control measures, finds a new study by UCL researchers. The systematic review*, published in Lancet Digital Health , shows that evidence around the effectiveness of automated contact tracing systems is currently very limited, and large-scale manual contact tracing alongside other public health control measures - such as physical distancing and closure of indoor spaces such as pubs - is likely to be required in conjunction with automated approaches. The team found 15 relevant studies by reviewing more than 4,000 papers on automated and partially-automated contact tracing, and analysed these to understand the potential impact these tools could have in controlling the COVID-19 pandemic. Lead author Dr Isobel Braithwaite (UCL Institute of Health Informatics) said: "Across a number of modelling studies, we found a consistent picture that although automated contact tracing could support manual contact tracing, the systems will require large-scale uptake by the population and strict adherence to quarantine advice by contacts notified to have a significant impact on reducing transmission." The authors suggest that even under optimistic assumptions - where 75-80% of UK smartphone owners are using a contact tracing app, and 90-100% of identified potential close contacts initially adhere to quarantine advice - automated contact tracing methods would still need to be used within an integrated public health response to prevent exponential growth of the epidemic.