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    Contact tracing will start as soon as possible

    Professor Steven Van Gucht, spokesperson of the federal public health authority, Sciensano © Belga

    When lifting the lockdown restrictions, Belgium will have to increase testing and start contact tracing.

    The issue of contact tracing, which until now has been missing in the Belgian measures to fight the coronavirus, was mentioned as the last point in the decision taken by the National Security Council on Friday (24 April) on the gradual lifting of restrictions (deconfinement) during May and June.

    Under “conditions for success”, the decision states that to ensure deconfinement in the best possible conditions, testing and tracing will play a major role. “For tracing, a coordinated strategy between regions and communities will be implemented, with the support of federal experts.”

    “Contact tracing should start already in May, as soon as possible,” said professor Steven Van Gucht, spokesperson of Sciensano, to The Brussels Times. “We intend to set up call centres with 2,000 staff.”

    He thought that main method of tracing would be manual while a mobile phone application will be a complimentary method. “I’ll recommend the use of an application but it cannot be sufficient.”

    In its joint roadmap (15 April) towards a common lifting of the measures in the EU member states, the European Commission gave a green light to the use of mobile applications that warn citizens of an increased risk due to contact with a person tested positive for COVID-19.

    “Such tracing is particularly relevant in the phase of lifting containment measures, when the infection risk grows as more and more people get in contact with each other,” the Commission wrote.

    The European Centre for Disease Prevention and Control (ECDC) has also endorsed the roadmap and wrote in its latest risk assessment (23 April) that a “framework for contact tracing, based on extensive testing, active case finding, early detection of cases, isolation of cases, quarantine and follow-up of contacts, possibly supported by electronic tools and applications,” should be put in place.

    “The world will not and cannot go back to the way things were,” said WHO Director-General Dr Tedros Adhanom Ghebreyesus last week and stressed the importance of testing and tracing.

    “There must be a ´new normal’ – a world that is healthier, safer and better prepared. The same public health measures we have been advocating since the beginning of the pandemic must remain the backbone of the response in all countries. Find every case; Isolate every case; Test every case; Care for every case; Trace and quarantine every contact.”

    Blood tests

    Asked about serological testing (blood test of antibodies) during the phase-out period, Van Gucht agreed that such tests should be carried out but they are not yet accurate and need first to be validated. Antibodies created as a result of COVID-19 infection can protect against future minor infections but not against serious infections.

    He does not believe that the testing can be used on a wider scale. “It could be interesting to use serological testing in settings such as hospitals and retirement homes to identify staff that risk of being infected.”

    Preliminary sample tests of antibodies in blood banks in Belgium are not that promising and show that only 4,3 percent of the population had developed antibodies by 14 April. “The sample was representative of all age groups and different parts of the country,” Van Gucht says.

    The figure can be seen as a lower limit and he did not expect that it would exceed 10 % by the end of June. The actual infection rate in Brussels until now is probably higher. If not all infected persons develop antibodies after recovery, nor become immune against serious infections in the future, there is a problem in achieving group immunity.

    WHO wrote yesterday (25 April) that it continues to review the evidence on antibody responses to coronavirus infection. “Most of these studies show that people who have recovered from infection have antibodies to the virus. However, some of these people have very low levels of neutralizing antibodies in their blood, suggesting that cellular immunity may also be critical for recovery.”

    According to WHO, laboratory tests that detect antibodies in people, including rapid immunodiagnostic tests, need further validation to determine their accuracy and reliability. Inaccurate immunodiagnostic tests may falsely categorize people as positive or negative which will have serious consequences and will affect control efforts.

    Other countries, such as Italy and Germany, seem to believe more in serological testing. Germany plans to sample the entire population for antibodies in the coming months. Preliminary results from a small German town showed that 14 % of the inhabitants had developed anti-bodies.

    M. Apelblat
    The Brussels Times