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A member of the military conducts a coronavirus disease (COVID-19) check-up at a drive-thru testing site in Chessington, London, Britain, April 24, 2020

Is ‘intensive’ contact tracing the key to controlling the spread of coronavirus?

Image credit: REUTERS/Henry Nicholls/File Photo

A combination of extensive contact tracing, isolating cases and testing may reduce the spread of the novel coronavirus, according to a new study carried out in China.

The study, published in Lancet Infectious Diseases, was conducted by researchers at the Harbin Institute of Technology in Shenzhen, China.

The research team analysed data from 391 Covid-19 patients and 1,286 of their close contacts. It found that extensive contact tracing and rapid isolation of potentially infected individuals reduced the time that infectious people interacted with others in the community by two days.

Patients with symptoms were isolated and treated in the hospital before their test results were confirmed, while close contacts without symptoms were quarantined at designated facilities. Furthermore, close contacts who tested negative were quarantined at home or at a specified facility and monitored for 14 days.

The study also found that a fifth of people diagnosed with Covid-19 after being contract traced – 17 out of 87 – had not developed any symptoms, while 30 per cent did not have a fever.

Although the exact length of time a person remains infectious is not yet known, reducing the amount of time that infected people interacted with others appears to have helped reduce the virus spreading, the study added.

“The experience of Covid-19 in the city of Shenzhen may demonstrate the huge scale of testing and contact tracing that’s needed to reduce the virus spreading,” said Dr Ting Ma of the university. “Some of the strict control measures enforced here, such as isolating people outside their homes, might be unlikely to be replicated elsewhere, but we urge governments to consider our findings in the global response to Covid-19.”

To achieve similar results, the researchers noted that other countries might be able to combine near-universal testing and intensive contact tracing with social distancing and partial lockdowns. “Although no lockdown measures were introduced in Shenzhen until the end of the study period, Wuhan’s lockdown could have significantly restricted the spread of coronavirus to Shenzhen,” Ma said.

The researchers noted, however, that limitations of the study include potentially missing data, as it’s nearly impossible to track every single potential contact, especially asymptomatic ones.

In a commentary accompanying the study, the lead epidemiologist at the National Institutes of Health, Dr Cécile Viboud, explained: “Because Shenzhen, an affluent city of 12.5 million north of Hong Kong, was affected early in the pandemic and reacted quickly to its Covid-19 outbreak, it’s an interesting blueprint for other countries to learn from.

According to Viboud, who was not connected for the research, countries looking toward post-lockdown strategies should take notes from China, Singapore, Taiwan, South Korea, Germany and Iceland, which have either successfully controlled Covid-19 transmission within their borders or have low mortality rates.

“Successful strategies include ample testing and contact tracing, supplemented by moderate forms of social distancing,” Viboud wrote, adding that since large-scale contact testing is labour intensive and prone to inaccuracy, a technology-based approach is needed.

He also wrote that while many experts are concerned about the privacy implications of digital contact tracing, “enhanced case-finding and contact tracing should be part of the long-term response to this pandemic”.

In related news, Alessandra Pierucci, chair of the Council of Europe’s data protection 'Convention 108' committee, and Jean-Philippe Walter, the Council of Europe’s data protection commissioner, have warned about possible side-effects of digital contact-tracing applications in the prevention of the Covid-19 pandemic.

In a joint statement issued today (April 28), Pierucci and Walter called for adequate safeguards to be put in place to prevent risks to personal data and privacy. 

Since the start of the pandemic, governments and stakeholders involved in the fight against the virus have been relying on data analytics and digital technologies to address the health crisis. 

Mobile applications have been used in some countries and are being considered in others as a complementary response to the need to rapidly perform contact monitoring. The European Union (EU) drafted common rules for mobile apps used to track the spread of coronavirus.

The joint statement insists that wherever such technological solutions are used, strict legal and technical safeguards must be in place to mitigate any negative impact on the protection of personal data and privacy.

If these applications are deployed, it should be for a limited duration only and solely on a voluntary basis, the statement continued. These applications should also include specificities “by design” to prevent or minimise risks. For example, such apps must ensure that location data of individuals is not use; that no direct identification is possible, and that re-identification is prevented.

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