ted that 44% (95% confidence interval, 25‚Äì69%) of secondary cases were infected during the index cases‚Äô presymptomatic stage‚Äù <a href="https://www.nature.com/articles/s41591-020-0869-5">He, X., Lau, E.H.Y., Wu, P. et al</a>&nbsp;<a href="#fnref23" rev="footnote">&#8617;</a></p>
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	<li id="fn24">
	<p>‚ÄúContact tracing was a critical intervention in Liberia and represented one of the largest contact tracing efforts during an epidemic in history.‚Äù <a href="https://www.ncbi.nl