Scientists across the world believe that contact tracing using smartphone apps, such as India's Aarogya Setu, may help control the Covid-19 pandemic and ease the world out of the lockdown, while also flagging privacy issues with the technology-driven intervention.

Experts say the technology can help trace all the people who come in contact with a confirmed Covid-19 patient, helping medical authorities to track potential patients, test them, and further prevent the spread.

As India entered the second phase of lockdown from April 15, the government launched Aarogya Setu application which it said can track Covid-19 cases in addition to having other uses.

'There are two parts to contact tracing -- the first thing is that it traces your location through applications like Aarogya Setu and other apps used worldwide,' Aakash Sinha, an assistant professor at Shiv Nadar University in Uttar Pradesh, told PTI.

'The second part is that wherever you have been, whomever you are coming in contact with can also be traced. If I have the app and you also have it. So when I meet you, the apps can register that we came in close proximity,' he explained.

Contact tracing is being used by China, South Korea and many other countries that have successfully controlled the spread of the virus, Sinha noted.

He explained that the location of the places where a person goes is traced by using their phone's global positioning system (GPS) network as well as the location history.

Many of these apps also have a way to share information via Bluetooth or a Wi-Fi if they are very close, and that way this information exchange is done if somebody came in contact with an infected person, Sinha noted.

A global race to develop smartphone apps and other types of mobile phone surveillance systems to track and contain the spread of the novel coronavirus has started.

After studying the dynamics of the early coronavirus epidemic in China, researchers at the University of Oxford in the UK have demonstrated that almost half of all transmissions occurred before anyone showed symptoms.

They also estimated that delaying contact tracing by even a day from the onset of symptoms could make the difference between epidemic control and coronavirus resurgence.

To respond to this, the team rapidly conceptualised a simple mobile contact tracing app that it said can help control the spread of the novel coronavirus, save lives, and ease the population out of lockdown.

To boost the prospects of contact tracing, Google and Apple recently announced that they are working on a framework for smartphone apps that may help reopen the world economy.

In the US, Boston University scientists, including one of Indian origin, are working on a smartphone app that could let people know if they have come in contact with someone who has tested positive for COVID-19, while protecting their privacy.

The app being developed by researchers, including Mayank Varia, uses Bluetooth-enabled cell phones to notify a person if they have come into close proximity with someone infected with SARS-CoV-2, the novel coronavirus that causes COVID-19.

However in order to work efficiently, the app requires many people to use it, whether they have had COVID-19 or not, the researchers said.

Similarly, scientists at University College London (UCL) in the UK have developed a new Bluetooth contact tracing app for detecting COVID-19 proximity, that they say will help epidemiologists to analyse the spread of the pandemic while fully protecting individual privacy.

The system ensures no personal data ever leaves an individual's device, and is not centralised in a cloud server, meaning it is not able to be repurposed for anything other than public health, they said.

The scientists noted that several governments across the world have used contact tracing, as part of efforts to control the spread of the coronavirus.

However, concerns have been raised about what this means for individual privacy rights, and what happens if the data is misused or used beyond the initial purpose.

'There are a lot of concerns about Bluetooth tracing being administered centrally by governments, particularly in countries that have weaker privacy laws and concern for human rights,' said Michael Veale from UCL.

In India, Sinha said, the government is 'definitely' going to link phone numbers and whatever data users of these apps have in their smartphones with the location.

'But as per reading the latest privacy policy of Aarogya Setu app, it uses that private information to only alert you in case you are traced to be in touch with somebody with the infection,' Sinha explained.

'The government is taking the responsibility that they are not going to use your private information for anything else,' he said.

Emphasising on the need for adopting contact tracing, he said, the last time the pandemic like this occurred was in 1918, when the Spanish flu outbreak happened in which India lost six per cent of its population.

'And if you look at what 6 per cent will be today, you are talking like 10 crore people, Sinha noted.

'This is not an ordinary situation. This is extra-ordinary, happening once in a century and some extra-ordinary measures will need to be taken,' he added.