London, Aug 21 (IANS): Researchers have claimed that contract tracing apps being used to reduce the spread of Covid-19 are unlikely to be effective without proper uptake and support from concurrent control measures.

The study, published in the journal Lancet Digital Health, that evidence around the effectiveness of automated contact tracing systems is currently very limited.

The researchers stressed that 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.

"The review shows that, at present, there is insufficient evidence to justify reliance on automated contact tracing approaches without additional extensive public health control measures," said study lead author Isobel Braithwaite from the University College London in the UK.

In total, 4,033 papers were reviewed, which allowed researchers to identify 15 papers with useful data.

The seven studies that addressed automated contact tracing directly were modelling studies that all focused on Covid-19.

Five studies of partially-automated contact tracing were descriptive observational studies or case studies, and three studies of automated contact detection looked at a similar disease context to Covid-19 but did not include subsequent tracing or contact notification.

"Partially-automated systems may have some automated processes, for instance in determining the duration of follow-up of contacts required, but do not use the proximity of smartphones as a proxy for contact with an infected person".

Analysis of automated contact tracing apps generally suggested that high population uptake of relevant apps is required alongside other control measures, while partially-automated systems often had better follow-up and slightly more timely intervention.

"Although automated contact tracing shows some promise in helping reduce transmission of Covid-19 within communities, our research highlighted the urgent need for further evaluation of these apps within public health practice, Dr Braithwaite said.

"As none of the studies we found provided real-world evidence of their effectiveness, and to improve our understanding of how they could support manual contact tracing systems," Braithwaite noted.