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Belgian researchers warn against holiday reliance on COVID antigen tests

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By Reuters
Belgian researchers warn against holiday reliance on COVID antigen tests
Belgian researchers warn against holiday reliance on COVID antigen tests   -   Copyright  Thomson Reuters 2021   -  

<div> <p><span class="caps">AMSTERDAM</span> – Belgian researchers on Tuesday issued a pre-holiday warning against over-reliance on <span class="caps">COVID</span>-19 rapid antigen tests, saying they believed the breath of people infected with the disease had high levels of virus in the first two days after an infection — a period when many antigen tests were negative.</p> <p>The organizations involved said they were communicating their findings in advance of a peer-reviewed publication in the interests of public health, as many families may be planning to use antigen tests as a way of screening for illness before family gatherings.</p> <p>“A negative rapid antigen test just before a meeting offers no guarantee to protect others, in particular when the person tested has recently been exposed to the virus,” said Emmanuel Andre, a microbiologist at KU Leuven, which conducted the research together with UZ Leuven, a university hospital, and <span class="caps">IMEC</span>, a microelectronics think-tank.</p> <p>Scientists were already aware that exhaled particles are key in spreading the virus, but finding high levels of virus at the start of an infection was surprising and is a “first indication” the virus may be transmitted very early in an infection, Andre said.</p> <p>“A negative antigen test should not replace self-isolation when the chance of developing the disease is high, such as during the first 7 days following a high-risk contact,” he said.</p> <p>In their study, researchers took 58 people who had been in close proximity with someone who was infected, and tested them regularly over a two-week period with multiple types of tests.</p> <p>Of the 58, 11 later developed <span class="caps">COVID</span>-19. However, during the first two days of their infection, antigen tests failed to detect it half the time. <span class="caps">PCR</span> tests obtained by nose swabs reliably detected the disease. The aerosol tests, which are a type of <span class="caps">PCR</span> test that works by collecting breath and testing it on a specialized silicon chip, showed high virus levels in breath as early as the first day after an infection.</p> <p/> </div>